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NAKAI Masaaki

    Department of Mechanical Engineering　Professor
Last Updated :2024/04/25

Researcher Information

URL

J-Global ID

Research Areas

  • Manufacturing technology (mechanical, electrical/electronic, chemical engineering) / Machine materials and mechanics
  • Life sciences / Biomaterials
  • Life sciences / Biomedical engineering
  • Nanotechnology/Materials / Structural and functional materials

Academic & Professional Experience

  • 2021 - Today  Kindai UniversityFaculty of Science and EngineeringProfessor
  • 2016 - 2021  Kindai UniversityFaculty of Science and EngineeringAssociate Professor
  • 2010 - 2016  Tohoku UniversityInstitute for Materials ResearchAssociate Professor
  • 2007 - 2010  Tohoku UniversityInstitute for Materials ResearchAssistant Professor
  • 2006 - 2007  Tohoku UniversityInstitute for Materials ResearchResearch Associate

Association Memberships

  • THE IRON AND STEEL INSTITUTE OF JAPAN   THE JAPANESE SOCIETY FOR BIOMATERIALS   THE JAPAN INSTITUTE OF LIGHT METALS   THE JAPAN INSTITUTE OF METALS AND MATERIALS   THE JAPAN SOCIETY OF MECHANICAL ENGINEERS   JAPAN FOUNDRY ENGINEERING SOCIETY   

Published Papers

  • Kosuke Ueki; Kyosuke Ueda; Masaaki Nakai; Takayoshi Nakano; Takayuki Narushima
    Key Engineering Materials Trans Tech Publications, Ltd. 967 115 - 120 2023/12 
    The Co-20Cr-15W-10Ni (CCWN, mass%) alloy, registered as American society of testing and materials (ASTM) F90, has been widely used as a balloon-expandable stent because of its excellent balance between its mechanical properties and corrosion resistance. To realize a less invasive stent placement, the stent diameter must be reduced, which implies that the stent strut thickness must be reduced. As such, the CCWN alloy must be high in strength and ductility while maintaining a low yield stress to facilitate the expansion and suppression of stent recoil. In this study, we focus on the effects of the adding Mn/Fe on the microstructure, mechanical properties, and corrosive properties of CCWN alloys. A 6 mass% Mn-added CCWN alloy with a grain size of approximately 20 μm prepared in this study exhibits excellent balance between tensile strength and ductility. In addition, it exhibits a lower yield stress while maintaining a high tensile strength compared with the ASTM F90 alloy. Meanwhile, a 6 mass% Fe-added CCWN alloy exhibits a higher ductility compared with the ASTM F90 alloy. The addition of Mn or Fe to the CCWN alloy increases the stacking fault energy of the alloy and suppresses strain-induced martensitic transformation during plastic deformation, thus improving the ductility of the alloy. Results of polarization tests show that the 6 mass% Mn-or Fe-added CCWN alloys exhibit the same corrosion current density as the ASTM F90 alloy. Mn-added Co-Cr-W-Ni alloys are suitable for use in balloon-expandable stents.
  • Qiang Li; Yan Liu; Huanhuan Yu; Masaaki Nakai; Mitsuo Niinomi; Kenta Yamanaka; Akihiko Chiba; Takuya Ishimoto; Takayoshi Nakano
    Vacuum 215 112311  0042-207X 2023/09 [Refereed]
     
    To study the effect of O on β-Ti alloys with various β phase stability, Ti–xNb–0.4O (x = 30, 32, 34, 36, 38, 40, 42, mass%) alloys were prepared by arc melting followed by homogenization, hot rolling, and solution treatment. To ensure the O content of the alloys, melting and hot rolling were performed under an Ar atmosphere, and homogenization and solution treatment were performed under vacuum conditions. The mass fractions of O in the Ti–Nb–O alloys were finally accurately controlled in the range of 0.4–0.5%. The phase composition of the alloys was determined by analyzing the X-ray diffraction patterns, the microstructure was observed by optical microscopy, and the mechanical properties were measured by tensile tests. The ω phase and α" phase were found in the solution-treated Ti–30Nb–0.4O. Ti–30Nb–0.4O showed the lowest yield strength owing to the existence of the α" phase. O suppressed ω phase and α" phase transformations during quenching, and showed an obvious solution-strengthening effect. Because the O content of the alloys was essentially the same, the Ti–xNb–0.4O alloys showed similar tensile strengths. The Young's moduli of the alloys ranged from 60 to 69 GPa, and the elongations were all higher than 15%. Particularly, Ti–36Nb–0.4O exhibited desirable mechanical properties, including a Young's modulus of 61 GPa, a tensile strength of 760 MPa, and an elongation of approximately 35%.
  • Hakan Yilmazer; Ihsan Caha; Burak Dikici; Fatih Toptan; Murat Isik; Mitsuo Niinomi; Masaaki Nakai; Alexandra Cruz Alves
    Crystals MDPI AG 13 (4) 590 - 590 2023/03 [Refereed]
     
    In this study, the influence of the high-pressure torsion (HPT) processing parameters and solution treatment (ST) on the corrosion and tribocorrosion behavior of CoCrMo (CCM) alloys was investigated for possible usage in biomedical applications. The corrosion behavior of the CCM alloys was investigated by using potentiodynamic scanning (PDS) and electrochemical impedance spectroscopy (EIS) tests. Tribocorrosion tests were carried out in a reciprocating ball-on-plate tribometer at 1 Hz, 1 N load, and 3 mm stroke length for 2 h. All electrochemical measurements were performed using a potentiostat in standard phosphate-buffered saline (PBS) solution at body temperature (37 ± 2 °C). The samples were characterized by using a scanning electron microscope (SEM), transmission electron microscope (TEM), optical microscope (OM), and X-ray diffraction (XRD). The deepness and width of wear tracks were examined by using a profilometer. The results showed that HPT and ST processes did not affect significantly the corrosion resistance of samples. However, the ST-treated samples had a higher material loss during sliding in standard phosphate-buffered saline (PBS) at body temperature as compared to HPT-treated samples.
  • Kosuke Ueki; Ryo Hirano; Masaaki Nakai
    Materials Today Communications Elsevier BV 34 105465  2352-4928 2023/03 [Refereed]
  • Shunsei Takeda; Kosuke Ueki; Kyosuke Ueda; Masaaki Nakai; Takayoshi Nakano; Takayuki Narushima
    Materials Science and Engineering: A Elsevier BV 862 144505  0921-5093 2023/01 [Refereed]
  • Masaaki Nakai; Kengo Narita; Koichi Kobayashi; Keisuke Sasagawa; Mitsuo Niinomi; Kazuhiro Hasegawa
    MATERIALS TRANSACTIONS Japan Institute of Metals 64 (1) 147 - 154 1345-9678 2023/01 [Refereed]
  • Norain Binti ABDULLAH; Daisuke MIYAZAKI; Ei YAMAMOTO; Kosuke UEKI; Masaaki NAKAI
    Mechanical Engineering Journal Japan Society of Mechanical Engineers 9 (6) 22-00282  2022/12 [Refereed]
  • Kazunori ASANO; Kenkichi FUJITO; Hiroyuki WATANABE; Masaya IWASAKI; Kosuke UEKI; Masaaki NAKAI
    Transactions of the JSME (in Japanese) Japan Society of Mechanical Engineers 88 (913) 22-00216  2022/09 [Refereed]
  • Norain Binti Abdullah; Daisuke Miyazaki; Ei Yamamoto; Kosuke Ueki; Masaaki Nakai
    Journal of Materials Research Springer Science and Business Media LLC 37 (16) 2536 - 2545 0884-2914 2022/08 [Refereed][Invited]
  • Oktay Yigit; Burak Dikici; Mosab Kaseem; Masaaki Nakai; Mitsuo Niinomi
    Journal of Materials Research Springer Science and Business Media LLC 37 (16) 2515 - 2524 0884-2914 2022/08 [Refereed][Invited]
  • Qiang LI; Qi HUANG; Jun-jie LI; Qian-feng HE; Masaaki NAKAI; Ke ZHANG; Mitsuo NIINOMI; Kenta YAMANAKA; Akihiko CHIBA; Takayoshi NAKANO
    Transactions of Nonferrous Metals Society of China Elsevier BV 32 (2) 503 - 512 1003-6326 2022/02 [Refereed]
     
    Zr was added to Ti–Nb–Fe alloys to develop low elastic modulus and high strength β-Ti alloys for biomedical applications. Ingots of Ti–12Nb–2Fe–(2, 4, 6, 8, 10)Zr (at.%) were prepared by arc melting and then subjected to homogenization, cold rolling, and solution treatments. The phases and microstructures of the alloys were analyzed by optical microscopy, X-ray diffraction, and transmission electron microscopy. The mechanical properties were measured by tensile tests. The results indicate that Zr and Fe cause a remarkable solid-solution strengthening effect on the alloys; thus, all the alloys show yield and ultimate tensile strengths higher than 510 MPa and 730 MPa, respectively. Zr plays a weak role in the deformation mechanism. Further, twinning occurs in all the deformed alloys and is beneficial to both strength and plasticity. Ti–12Nb–2Fe–(8, 10)Zr alloys with metastable β phases show low elastic modulus, high tensile strength, and good plasticity and are suitable candidate materials for biomedical implants.
  • M. Zarka; B. Dikici; M. Niinomi; K.V. Ezirmik; M. Nakai; M. Kaseem
    Vacuum Elsevier BV 192 Article ID 110450  0042-207X 2021/10 [Refereed]
  • Masaaki Nakai; Takeshi Iwasaki; Kosuke Ueki
    J. Mech. Behav. Biomed. Mater. Elsevier BV 124 104808  1751-6161 2021/09 [Refereed]
  • Soh Yanagihara; Kosuke Ueki; Kyosuke Ueda; Masaaki Nakai; Takayoshi Nakano; Takayuki Narushima
    Metall. Mater. Trans. A Springer Science and Business Media LLC 52 (9) 4137 - 4145 1073-5623 2021/09 [Refereed]
     
    AbstractThis is the first report presenting the development of a Co–Cr–W–Ni–Mn alloy by adding 6 mass pct Mn to ASTM F90 Co–20Cr–15W–10Ni (CCWN, mass pct) alloy for use as balloon-expandable stents with an excellent balance of mechanical properties and corrosion resistance. The effects of Mn addition on the microstructures as well as the mechanical and corrosion properties were investigated after hot forging, solution treatment, swaging, and static recrystallization. The Mn-added alloy with a grain size of ~ 20 µm (recrystallization condition: 1523 K, 150 seconds) exhibited an ultimate tensile strength of 1131 MPa, 0.2 pct proof stress of 535 MPa, and plastic elongation of 66 pct. Additionally, it exhibited higher ductility and lower yield stress while maintaining high strength compared to the ASTM F90 CCWN alloy. The formation of intersecting stacking faults was suppressed by increasing the stacking fault energy (SFE) with Mn addition, resulting in a lower yield stress. The low-yield stress is effective in suppressing stent recoil. In addition, strain-induced martensitic transformation during plastic deformation was suppressed by increasing the SFE, thereby improving the ductility. The Mn-added alloys also exhibited good corrosion resistance, similar to the ASTM F90 CCWN alloy. Mn-added Co–Cr–W–Ni alloys are suitable for use as balloon-expandable stents.
  • Masaaki NAKAI; Rin SAWAKI; Kosuke UEKI; Shingo KUROSU; Tomonori NAMBU
    Transactions of the JSME (in Japanese) Japan Society of Mechanical Engineers 87 (900) 21 - 00101 2021/08 [Refereed]
  • Qiang Li; Hao Sun; Junjie Li; Xufeng Yuan; Masaaki Nakai; Mitsuo Niinomi; Takayoshi Nakano
    J. Mater. Eng. Perform. Springer Science and Business Media LLC 30 (8) 5719 - 5727 1059-9495 2021/08 [Refereed]
  • Qiang Li; Jinshuai Yang; Junjie Li; Ran Zhang; Masaaki Nakai; Mitsuo Niinomi; Takayoshi Nakano
    Mater. Trans. Japan Institute of Metals 62 (7) 1052 - 1055 1345-9678 2021/07 [Refereed]
  • Kosuke Ueki; Soh Yanagihara; Kyosuke Ueda; Masaaki Nakai; Takayoshi Nakano; Takayuki Narushima
    Mater. Trans. Japan Institute of Metals 62 (2) 229 - 238 1345-9678 2021/02 [Refereed]
     
    We investigated changes in the microstructure and mechanical properties of biomedical Co20Cr15W10Ni alloys (mass%) containing 8 mass% Mn and 03 mass% Si due to hot forging, solution treatment, cold swaging, and static recrystallization. The ©-phase (M XM X type cubic structure, M: metallic elements, X: C and/or N, space group: Fd-3m (227)) and CoWSi type Laves phase (C14 MgZn2 type hexagonal structure, space group: P63/mmc (194)) were confirmed as precipitates in the as-cast and as-forged alloys. To the best of our knowledge, this is the first report that reveals the formation of CoWSi type Laves phase precipitates in CoCrWNi-based alloys. The addition of Si promoted the formation of precipitates of both ©-phase and CoWSi type Laves phase. The solution-treated 8Mn+(0, 1)Si-added alloys exhibited TWIP-like plastic deformation behavior with an increasing work-hardening rate during the early to middle stages of plastic deformation. This plastic deformation behavior is effective in achieving both the low yield stress and high strength required to develop a high-performance balloon-expandable stent. The 8Mn+2Si-added alloy retained the CoWSi type Laves phase even after solution treatment, such that the ductility decreased but the strength improved. Additions of Mn and Si are effective in improving the ductility and strength of the CoCrWNi alloy, respectively. 6 12
  • Kosuke Ueki; Soh Yanagihara; Kyosuke Ueda; Masaaki Nakai; Takayoshi Nakano; Takayuki Narushima
    Materials Science Forum 1016 1503 - 1509 0255-5476 2021/01 [Refereed]
     
    The Co-20Cr-15W-10Ni (CCWN, mass%) alloy has excellent corrosion resistance and strength-ductility balance and is applied in almost all balloon-expandable stent platforms. To further reduce the invasiveness of stent placement, it is necessary to reduce the diameter of the stent. That is, both high strength and high ductility should be achieved while maintaining a low yield stress. In our previous studies, it was discovered that low-temperature heat-treatment (LTHT) at 873 K improves the elongation of the CCWN alloy. In this study, we focused on the grain refinement by swaging and static recrystallization to improve the strength of the alloy. The as-swaged alloy was recrystallized at 1373-1473 K for 100-300 s, followed by LTHT. A fine grain structure with an average grain size of 3-17 µm was obtained by static recrystallization. The η-phase (M X-M X type precipitates, M: metallic elements, X: C and/or N) formed during the recrystallization at 1373-1448 K. The alloys recrystallized at 1448 and 1473 K had a homogeneous structure with a small variation in the grain size. On the other hand, the alloys recrystallized at 1373 and 1423 K had an inhomogeneous structure in which fine and coarse grains were mixed. Both the strength and ductility of the CCWN alloy were improved by combining high-temperature short-time recrystallization and LTHT. 12 6
  • β型Ti-Nb基合金の低ヤング率化の要因と医療応用研究の現状
    仲井正昭; 新家光雄
    まてりあ 59 (11) 588 - 593 2020/11 [Refereed][Invited]
  • M. Zarka; B. Dikici; M. Niinomi; K.V. Ezirmik; M. Nakai; H. Yilmazer
    Vacuum Elsevier BV Article ID 109850  0042-207X 2020/10 [Refereed]
  • Saki Tanaka; Toshikazu Akahori; Mitsuo Niinomi; Masaaki Nakai
    Mater. Trans. Japan Institute of Metals 61 (10) 2017 - 2024 1345-9678 2020/10 [Refereed]
  • Qiang Li; Ran Zhang; Junjie Li; Qiang Qi; Xuyan Liu; Masaaki Nakai; Mitsuo Niinomi; Takayoshi Nakano
    J. Mater. Eng. Perform. Springer Science and Business Media LLC 29 (8) 5366 - 5373 1059-9495 2020/08 [Refereed]
     
    © 2020, ASM International. A series of Ti-(38-2x)Nb-xMo (wt.%) alloys are designed using 1% Mo to replace 2% Nb in order to gradually increase the β stability and obtain a low springback. The α″ phase is exhibited in Ti-38Nb and suppressed with an increasing Mo content. The Ti-38Nb and Ti-34Nb-2Mo alloys show stress-induced α″ martensite transformations during cold rolling and double yielding behavior in tensile tests. The Ti-30Nb-4Mo and Ti-26Nb-6Mo alloys exhibit nonlinear deformation owing to the metastable β phase. With an increase in the Mo content, Young’s modulus increases slightly from 68 GPa in Ti-38Nb to 73 GPa in Ti-26Nb-6Mo, owing to the increase in β stability. Mo shows a solution strengthening effect that gradually increases the tensile strength. Although a higher Young’s modulus was not observed to be induced through deformation in Ti-(38-2x)Nb-xMo alloys, low springback was obtained according to the three-point bending loading–unloading test. In particular, the Ti-38Nb and Ti-34Nb-2Mo alloys with stress-induced α″ martensite transformations exhibit low yielding stress and are thus easily deformed. The deformed α″ phase hardly reverts to the β matrix after unloading, and therefore, the plastic deformation is maintained.
  • Saki Tanaka; Toshikazu Akahori; Mitsuo Niinomi; Masaaki Nakai
    Journal of the Japan Institute of Metals and Materials Japan Institute of Metals 84 (6) 200 - 207 0021-4876 2020/06 [Refereed]
  • Qiang Li; Chao Cheng; Junjie Li; Ke Zhang; Kai Zhou; Masaaki Nakai; Mitsuo Niinomi; Kenta Yamanaka; Daixiu Wei; Akihiko Chiba; Takayoshi Nakano
    J. Mater. Eng. Perform. Springer Science and Business Media LLC 29 (5) 2871 - 2878 1059-9495 2020/05 [Refereed]
     
    A series of Ti-29Nb-(4, 7, 10, 13)Zr-2Cr alloys were fabricated to investigate the influence of Zr content on microstructures and mechanical properties. All the four alloys present a single β phase after solution treatment. With the increase in Zr content, the 0.2% proof stress is gradually increased from 388 MPa in Ti-29Nb-4Zr-2Cr to 713 MPa in Ti-29Nb-13Zr-2Cr. The Young’s modulus gradually is decreased from 80 GPa in Ti-29Nb-4Zr-2Cr to 63 GPa in Ti-29Nb-13Zr-2Cr. The elongation shows the same trend as that of Young’s modulus. The changes of mechanical properties are influenced by the β stability and solid solution strengthening effect, which are both enhanced by Zr addition. The Ti-29Nb-13Zr-2Cr alloy presents a Young’s modulus of 63 GPa, tensile strength of 730 MPa and elongation of 18% and is a promising biomedical material.
  • N.B. Abdullah; M. Nakai; Y. Kawamura; E. Yamamoto; M. Niinomi
    MATEC Web Conf. 321 Article ID 05015  2020 [Refereed]
  • M. Niinomi; T. Akahori; M. Nakai; Y. Koizumi; A. Chiba; T. Nakano; T. Kakeshita; Y. Yamabe-Mitarai; S. Kuroda; N. Motohashi; Y. Itsumi; T. Choda
    MATEC Web Conf. EDP Sciences 321 Article ID 11015 - 11015 2020 [Refereed]
     
    The microstructures, tensile properties, and fatigue lives of the forged Ti-17 using a 1500-ton forging simulator subjected to different solution treatments and a common aging treatment under both load- and strain-controlled conditions to evaluate high cycle fatigue and low cycle fatigue lives, respectively were examined. Then, the tensile properties, microstructures, and relationships between fatigue lives and the microstructural factors were discussed. The fatigue limit under load-controlled conditions increases with increasing solution treatment temperature up to 1143 K, which is in the (α + β) region. However, it decreases with further increase in the solution treatment temperature to 1203 K in the b region. The fatigue ratio at fatigue limit is increasing with decreasing solution treatment temperature, namely increasing the volume fraction of the primary α phase, and it relates well qualitatively with the volume fraction of the primary α phase when the solution treatment temperature is less than the b transus temperature. The fatigue life under strain-controlled conditions to evaluate the low cycle fatigue life increases with decreasing solution treatment temperature, namely increasing the volume fraction of the primary α phase. The fatigue life under strain-controlled conditions to evaluate the low cycle fatigue life relates well quantitatively with the tensile true strain at breaking of the specimen and the volume fraction of the primary α phase for each total strain range.
  • V. Khademi; H. Liu; M. Nakai; M. Niinomi; C.J. Boehlert
    MATEC Web Conf. 321 Article ID 11003  2020 [Refereed]
  • 航空機用チタン合金摩擦攪拌接合継手の高疲労強度化のための組織制御技術の開発
    仲井正昭; 新家光雄
    生産と技術 72 (4) 5 - 8 2020 [Invited]
  • N. Mitsuishi; E. Miura; M. Yamada; T. Chiba; H. Sato; Y. Watanabe; M. Ito; S. Takashima; M. Nakai; T. Akahori; M. Tanaka; M. Niinomi; T. Takeuchi
    Jpn. J. Appl. Phys. 59 (SA) SAAC09  0021-4922 2019/11 [Refereed]
     
    © 2019 The Japan Society of Applied Physics. Ti-29Nb-13Ta-4.6Zr (TNTZ) is one of the Ti alloys used for orthodontic wire. However, there is a problem that the metallic color of TNTZ may spoil the appearance of a row of teeth. In previous studies, white oxide coating on disk-shaped TNTZ samples was obtained by heat treatment or atmospheric-pressure plasma (APP) treatment. In this study, the fabrication process of white orthodontic wire by applying APP treatment is proposed. As a result, TNTZ wire which has a white oxide layer with comparable brightness to the surface of Japanese teeth has been successfully fabricated.
  • K. Ueki; S. Yanagihara; K. Ueda; M. Nakai; T. Nakano; T. Narushima
    Mater. Sci. Eng. A ELSEVIER SCIENCE SA 766 138400  0921-5093 2019/10 [Refereed]
     
    A process combining swaging, static recrystallization, and heat treatment at 873 K (low-temperature heat-treatment, LTHT) was developed for achieving both high ultimate strength and high ductility in Co-20Cr-15W-10Ni (mass%, CCWN) alloy for stent application. The alloys swaged to a sectional area reduction rate of 58.3% were annealed at 1373-1473 K for 30-300 s. Under annealing at 1373 K for 300 s, a fine grain structure with an average grain size of similar to 6 mu m formed, while under annealing at 1473 K, a structure with an average grain size of 12 mu m formed after 120 s. In the alloys annealed at 1373-1448 K, the formation of eta-phase precipitates (M6X-M12X type, M: metallic elements, X: C and/or N) was observed, while no precipitates were observed in the alloys annealed at 1473 K. The improvement in ultimate strength by grain refinement was confirmed. Alloys annealed at 1473 K showed higher ductility compared to those annealed at 1373-1448 K even if the grain size was similar. It is considered that the eta-phase precipitates deteriorated the ductility of the annealed alloys. LTHT suppressed the strain-induced martensitic gamma-to-epsilon transformation to improve the ductility of the fine-grained as well as coarse-grained alloys. Thus, regardless of the grain size, it is newly evidenced that LTHT effectively improves ductility in CCWN alloy. By combining high-temperature short-time annealing and LTHT, both the ultimate strength and ductility of Co-2OCr-15W-10Ni (mass%) alloy improved, and it was possible to provide properties suitable for next-generation balloon-expandable stents with Co-20Cr-15W-10Ni (mass%) alloy.
  • Qiang Li; Pu Miao; Junjie Li; Meifeng He; Masaaki Nakai; Mitsuo Niinomi; Akihiko Chiba; Takayoshi Nakano; Xuyan Liu; Kai Zhou; Deng Pan
    J. Mater. Eng. Perform. Springer Science and Business Media LLC 28 (9) 5501 - 5508 1059-9495 2019/09 [Refereed]
     
    β-Type Ti-Nb-based alloys exhibit satisfactory biocompatibility and low Young’s modulus for biomedical applications. The microstructure and mechanical properties of a series of Ti-(14, 16, 18, 20, 22, 24)Nb-2Fe alloys fabricated by arc melting were investigated by XRD, optical microscopy, and tensile tests. Both ω and α″ phases existed in the Ti-14Nb-2Fe alloy, while just a single β phase existed in the other alloys. Twinning is an important deformation mechanism that causes work hardening and twinning-induced plasticity. It was found in the Ti-(14, 16, 18, 20)Nb-2Fe alloys and not in the Ti-22Nb-2Fe alloy. The Ti-14Nb-2Fe alloy exhibited the highest tensile strength and the highest Young’s modulus owing to the existence of the ω phase. The tensile strength decreased gradually from 830 MPa (highest) for the Ti-14Nb-2Fe alloy to 540 MPa (lowest) for the Ti-24Nb-2Fe alloy with an increase in the Nb content. The Young’s modulus decreased from 90 GPa for the Ti-14Nb-2Fe alloy to 63 GPa for the Ti-22Nb-2Fe alloy and then increased to 71 GPa for the Ti-24Nb-2Fe alloy. Elongation shows the same trend as the Young’s modulus. The Ti-22Nb-2Fe alloy, with a low Young’s modulus of 63 GPa, tensile strength of 570 MPa, and 15% elongation, was found suitable for biomedical applications. The Ti-20Nb-2Fe alloy also exhibits a high tensile strength, a Young’s modulus ratio of 9.24 × 10 , and 18% elongation and is thus considered another valuable Ti alloy for biomedical applications. −3
  • Qiang Li; Xufeng Yuan; Junjie Li; Pan Wang; Masaaki Nakai; Mitsuo Niinomi; Takayoshi Nakano; Akihiko Chiba; Xuyan Liu; Deng Pan
    Mater. Trans. 60 (9) 1763 - 1768 1345-9678 2019/09 [Refereed]
     
    © 2019 The Japan Institute of Metals and Materials Biomedical Ti15Nb25Zr(0, 2, 4, 8)Fe (mol%) alloys are prepared by mixing pure element powders and spark plasma sintering (SPS). Specimens with diameters of 20 mm and thicknesses of 3 mm are obtained by sintering at 1000°C for 10 min followed by cooling in the furnace. Some of the specimens are then heat-treated at 900°C for 1 h followed by water quenching. Zr and Fe are dissolved in Ti; however, segregation of Nb is observed in all of the alloys. The ¢ and ¡AA phases are observed in the as-sintered and heat-treated specimens owing to the insufficient diffusion of the alloying elements. Fe stabilizes the ¢ phase and provides a solution-strengthening effect. With the increase in the Fe content in the as-sintered specimen, the compressive strength and micro-Vickers hardness are improved in the Ti15Nb25Zr(0, 2, 4)Fe alloys and slightly decreased in Ti15Nb25Zr8Fe. The as-sintered Ti15Nb25Zr4Fe alloy exhibits the maximum compressive strength of 1740 MPa. Although the plasticity is decreased by the Fe addition, a fracture strain of approximately 17% is obtained for Ti15Nb25Zr4Fe, indicating a good plasticity. The heat treatment cannot eliminate the segregation of Nb, but can improve the plasticity and slightly increase the strengths of Ti15Nb25Zr(0, 2, 4)Fe. Moreover, the heat-treated Ti15Nb25Zr8Fe exhibits a high strength of approximately 1780 MPa and fracture strain of approximately 19%. Therefore, good comprehensive mechanical properties, including high strengths, high hardnesses, and good plasticities, can be obtained in Fe-added ¢-Ti alloys prepared by SPS and subsequent optional short heat treatment.
  • Qiang Li; Qiang Qi; Junjie Li; Masaaki Nakai; Mitsuo Niinomi; Yuichiro Koizumi; Daixiu Wei; Kenta Yamanaka; Takayoshi Nakano; Akihiko Chiba; Xuyan Liu; Deng Pan
    Materials Transactions 60 (9) 1755 - 1762 1345-9678 2019/09 [Refereed]
     
    © 2019 Japan Institute of Metals (JIM). All rights reserved. Deformation-induced higher Young’s modulus can satisfy the contradictory requirements of Ti alloys for spinal-fixation applications, which demand a high Young’s modulus to reduce springback during operations and a low Young’s modulus to prevent stress shielding effect for patients after surgeries. In this study, TNTZ(1, 3, 5)Mo are designed by adding Mo and Ti to Ti29Nb13Ta4.6Zr (TNTZ) in order to maintain low initial Young’s modulus and achieve low springback. All the solutionized alloys show single ¢ phase with increasing the ¢ stability by Mo addition. They show low Young’s moduli less than 65 GPa, similar ultimate tensile strength of 650 MPa and elongation around 20%. The springback of TNTZ3Mo and TNTZ5Mo is lower than that of TNTZ and TNTZ1Mo owing to their more stable ¢ phase. After cold rolling, TNTZ3Mo shows the largest increasing ratio of 25% in Young’s modulus and the highest ultimate tensile strength owning to the appearance of deformation-induced ½ phase. With the low initial Young’s modulus of 59 GPa, TNTZ3Mo is a potential candidate to make the spinal rods in spinal fixation devices.
  • M. Nakai; M. Niinomi; H.H. Liu; T. Kitashima
    Mater. Trans. 60 (9) 1749 - 1754 1345-9678 2019/09 [Refereed]
     
    The effect of Si addition on the microstructure and mechanical properties of a near-¢ titanium alloy Ti-17 with fully lamella microstructure was investigated. It was found that the microstructure of Ti-17 with silicon exhibited the absence of a continuously thick ¡ layer along prior-¢ grain boundaries (grain boundary ¡), while the grain boundary ¡ was distinctively formed in Ti-17 without Si. The formation of (Ti, Zr) silicide particles at the prior-¢ grain interior and its grain boundaries were observed, and the presence of these particles were related to the disappearance of grain boundary ¡ similar to the oxygen scavenging effect of boride particles reported previously. With regard to mechanical properties, Ti-17 with silicon exhibits higher strength and lower ductility compared with Ti-17 without Si. Ductile transgranular fracture morphology was observed even on the fracture surface of Ti-17 with Si after tensile test.
  • M. Niinomi; T. Akahori; M. Nakai; Y. Koizumi; A. Chiba; T. Nakano; T. Kakeshita; Y. Yamabe-Mitarai; S. Kuroda; N. Motohashi; Y. Itsumi; T. Choda
    Mater. Trans. 60 (9) 1740 - 1748 1345-9678 2019/09 [Refereed]
     
    ©2019 The Japan Institute of Metals and Materials. The fatigue lives of forged Ti-17 using a 1500-ton forging simulator subjected to different solution treatments and a common aging treatment were evaluated under both load- and strain-controlled conditions: high and low cycle fatigue lives, respectively. Then, the tensile properties and microstructures were also examined. Finally, the relationships among fatigue lives and the microstructural factors and tensile properties were examined. The microstructure after solution treatment at 1203 K, which is more than the ¢ transus temperature, and aging treatment exhibits equiaxed prior ¢ grains composed of fine acicular ¡. On the other hand, the microstructures after solution treatment at temperatures of 1063, 1123, and 1143 K, which are less than the ¢ transus temperature, and aging treatment exhibit elongated prior ¢ grains composed of two different microstructural feature regions, which are acicular ¡ and fine spheroidal ¡ phase regions. The 0.2% proof stress, ·0.2, and tensile strength, ·B, increase with increasing solution treatment temperature up to 1143 K within the (¡ + ¢) region, but decrease with further increasing solution treatment temperature to 1203 K within the ¢ region. The elongation (EL) and reduction of area (RA) decrease with increasing solution treatment temperature, and it becomes nearly 0% corresponding to a solution treatment temperature of 1203 K. The high cycle fatigue limit increases with increasing solution treatment temperature up to 1143 K, corresponding to the (¡ + ¢) region. However, it decreases with further increase in the solution treatment temperature to 1203 K in the ¢ region. The fatigue ratio in high cycle fatigue life region is increasing with decreasing solution treatment temperature, namely increasing the volume fraction of the primary ¡ phase, and it relates well qualitatively with the volume fraction of the primary ¡ phase when the solution treatment temperature is less than the ¢ transus temperature. The low cycle fatigue life increases with decreasing solution treatment temperature, namely increasing the volume fraction of the primary ¡ phase. The low cycle fatigue life relates well quantitatively with the tensile true strain at breaking of the specimen and the volume fraction of the primary ¡ phase for each total strain range of low cycle fatigue testing.
  • M.A.-H. Gepreel; M. Niinomi; M. Nakai; M. Morinaga
    JOM 71 3631 - 3639 2019/06 [Refereed]
  • Qiang Li; Guanghao Ma; Junjie Li; Mitsuo Niinomi; Masaaki Nakai; Yuichro Koizumi; Dai Xiu Wei; Tomoyuki Kakeshita; Takayoshi Nakano; Akihiko Chiba; Xuyan Liu; Kai Zhou; Deng Pan
    J. Mater. Sci. 54 (11) 8675 - 8683 0022-2461 2019/06 [Refereed]
     
    © 2019, Springer Science+Business Media, LLC, part of Springer Nature. Different amounts of Cr were added to a metastable β-type Ti–22Nb (at.%) alloy to obtain desirable mechanical properties, including a low Young’s modulus, high strength, and good plasticity. The mechanical properties and microstructural changes were investigated. Cr has a high ability to stabilize the β phase, as well as suppress both α″ martensite and ω phase transformations during quenching and the stress-induced α″ martensite transformation during tension. Solid solution strengthening is scarcely achieved by Cr addition. The changes in mechanical properties can be attributed to the different β stabilities. The Ti–22Nb–(0,1)Cr alloys have metastable β phases and exhibit double yielding phenomena, indicating a stress-induced α″ martensite transformation. The Ti–22Nb–(2,3)Cr alloys with stable β phases exhibit distinct work hardening caused by a {332}β<113>β twinning, which also occurs in the Ti–22Nb–(0,1)Cr alloys, but not in the Ti–22Nb–4Cr alloy. Low Young’s moduli of approximately 60 GPa are obtained for the Ti–22Nb–(1,2)Cr alloys. The Ti–22Nb–2Cr alloy exhibits desirable properties for biomedical applications, including an ultimate tensile strength of approximately 600 MPa and elongation of approximately 20%.
  • M. Nakai; M. Niinomi; K. Komine; H.H. Liu; Y. Morisada; H. Fujii
    Mater. Sci. Eng. A 742 553 - 563 2019/01 [Refereed]
  • K. Ueki; M. Abe; K. Ueda; M. Nakai; T. Nakano; T. Narushima
    Mater. Sci. Eng. A ELSEVIER SCIENCE SA 739 53 - 61 0921-5093 2019/01 [Refereed]
     
    The microstructure and tensile properties of Co-27Cr-6Mo (mass%) alloys heat-treated at 673-1373 K were studied. Lower elongation was observed after heat treatment at 1073 K due to formation of carbonitride precipitates. In contrast, when low-temperature heat treatment (LTHT) was applied at 673-873 K, both the ultimate tensile strength and elongation synchronously improved compared with the solution-treated alloy. Electron backscatter diffraction analysis for plastic-strained alloys and in situ X-ray diffraction analysis under stress induced conditions revealed that the strain-induced martensitic transformation (SIMT) of the gamma(fcc)-phase to epsilon(hcp)-phase during plastic deformation was suppressed by the LTHT. Stacking faults (thin epsilon-phase) were observed to collide in the LTHT alloys. The following mechanisms for the synchronous improvement in the tensile strength and elongation after LHTH are proposed. First, stacking faults with multiple variants were formed during LTHT. Then, the epsilon-phase of a single variant formed by SIMT during plastic deformation collides with preexisting multi-variant stacking faults formed during LTHT, increasing the tensile strength. In addition, the SIMT during plastic deformation is suppressed in the high-plastic-strain region by the collision. This decreases the total amount of epsilon-phase formed during plastic deformation, which improves the ductility. We demonstrated that LTHT of Co-Cr-Mo alloys effectively improves the performance and mechanical safety of spinal fixation implants, which often fracture because of fatigue cracking.
  • B. Dikici; M. Niinomi; M. Topuz; S.G. Koc; M. Nakai
    J. Sol-Gel Sci. Technol. 87 (3) 713 - 724 2018/09 [Refereed]
  • Kosuke Ueki; Kyosuke Ueda; Masaaki Nakai; Takayoshi Nakano; Takayuki Narushima
    Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science Springer Boston 49 (6) 2393 - 2404 1073-5623 2018/06 [Refereed]
     
    Microstructural changes were observed during the plastic deformation of ASTM F90 Co-20Cr-15W-10Ni (mass pct) alloy heat-treated at 873 K (600 °C) for 14.4 ks, and analyzed by electron backscatter diffraction and in situ X-ray diffraction techniques. The obtained results revealed that the area fraction of the ε-phase (fε) in the as-received alloy was higher than that in the heat-treated alloy in the low-to-middle strain region (≤ 50 pct), whereas the fε of the heat-treated alloy was higher than that of the as-received alloy at the fracture point. During plastic deformation, the ε-phase was preferentially formed at the twin boundaries of the heat-treated alloy rather than at the grain boundaries. According to the transmission electron microscopy observations, the thin ε-phase layer formed due to the alloy heat treatment acted as the origin of deformation twinning, which decreased the stress concentration at the grain boundaries. The results of anodic polarization testing showed that neither the heat treatment at 873 K (600 °C) nor plastic deformation affected the alloy corrosion properties. To the best of our knowledge, this is the first study proving that the formation of a thin ε-phase layer during the low-temperature heat treatment of the studied alloy represents an effective method for the enhancement of the alloy ductility without sacrificing its strength and corrosion properties.
  • B. Dikici; M. Niinomi; M. Topuz; Y. Say; B. Aksakal; H. Yilmazer; M. Nakai
    Protection of Metals and Physical Chemistry of Surfaces Pleiades Publishing 54 (3) 457 - 462 2070-206X 2018/05 [Refereed]
     
    In this study, hydroxyapatite (HA) based composite films were successfully syntheses on the β-type Ti29Nb13Ta4.6Zr (TNTZ). The solutionized TNTZ substrates coated with HA and HA/Titania (TiO2) bioactive composite coatings by sol-gel method under various sintering parameters related to sintering temperatures and heating ramp rates. Microstructural observations of the coatings revealed that apatite was formed on the substrates. The hardness values of the coatings increase with increasing both the sintering temperature and the TiO2 concentration in the coatings layer. However, it was found that the heating ramp rate of the sintering was not affecting the hardness values so much. Also, the hardness values of the HA/TiO2 composite coatings at all sintering temperatures were higher than only HA coated TNTZ samples due to the existence TiO2 phases in the HA matrix. Results indicating that the doping of HA with TiO2, improve the physical consistency between the coating layer and the substrates and provide a better inter-particle bonding due to the existence TiO2 phases in the HA.
  • Qiang Li; Dong Ma; Junjie Li; Mitsuo Niinomi; Masaaki Nakai; Yuichiro Koizumi; Daixiu Wei; Tomoyuki Kakeshita; Takayoshi Nakano; Akihiko Chiba; Kai Zhou; Deng Pan
    Materials Transactions 59 (5) 858 - 860 1345-9678 2018/05 [Refereed]
     
    © 2018 The Japan Institute of Metals and Materials. Oxygen was added to Ti38Nb (mass%) alloys to improve their mechanical properties. Ti38NbxO (x = 0.13, 0.24, 0.46, mass%) alloys were prepared by arc melting, and subsequently subjected to homogenization, hot rolling, and solution treatment. It was found that adding oxygen suppresses the martensite transformation and exhibits strong solution strengthening effect. Single ¢ phase is obtained in Ti38Nb0.24O, whereas Ti38Nb0.13O is composed of both ¡AA and ¢ phases. Both alloys exhibit double yielding phenomena during tension, indicating a stress-induced martensitic transformation. Ti38Nb0.46O exhibits a non-linear deformation, a low Young's modulus of 62 GPa, high tensile strength up to 780 MPa, and elongation around 23%, which are promising characteristics for biomedical applications.
  • T. Homma; A. Arafah; D. Haley; M. Nakai; M. Niinomi; M. P. Moody
    MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING ELSEVIER SCIENCE SA 709 312 - 321 0921-5093 2018/01 [Refereed]
     
    The effects of alloying elements in Ti-29Nb-13Ta-4.6Zr (wt%) (TNTZ) alloys with low Young's modulus for biomedical applications on microstructural evolution during aging, in particular, at an aging temperature of 400 degrees C have been determined. The peak hardness is obtained by co-precipitation of alpha and omega phases. O addition stabilizes omega phases; as a result, formation of omega is enhanced with increasing the O content as an alloying element, resulting in prevention of the growth of the alpha phases due to soft impingement. Because of the stress caused by the omega to alpha transformation, the alpha phase often contains defects within its internal structure. Although Zr is known to be a neutral element within Ti, here we show that Zr acts as weak beta stabilizer. At the beta/alpha interface, Zr enrichment appears to be due to a solute drag mechanism. In addition, a slight increase in Zr composition in the beta/omega interface has also been detected using atom probe. Dispersion of omega phases and segregation of Zr to the beta/alpha interface lead to fine alpha phase precipitation, resulting in an increase in the hardness of the O-added TNTZ alloys.
  • サルモネラ硫化水素産生による銀および銅の抗菌性比較評価
    翠川裕; 仲井正昭; 新家光雄
    銅と銅合金 57 (1) 318 - 322 2018 [Refereed]
  • X. L. Zhao; L. Li; M. Niinomi; M. Nakai; D. L. Zhang; C. Suryanarayana
    ACTA BIOMATERIALIA ELSEVIER SCI LTD 62 372 - 384 1742-7061 2017/10 [Refereed]
     
    Good ductility, low magnetic susceptibility, and tunable Young's modulus are highly desirable properties for materials usage as spinal fixation rods. In this study, the effects of niobium content on the microstructure, magnetic susceptibility, and mechanical properties of Zr-xNb (13 <= x <= 23 wt%) alloys were investigated. For the Zr-15Nb and Zr-17Nb alloys, a remarkable increase in Young's modulus was achieved due to the occurrence of deformation-induced o.) phase transformation. This was the result of the competition of two factors associated with the Nb content: an increase of the stability of beta phase and a decrease of the amount of athermal to phase with increasing Nb content. When the Nb content was 15% or 17%, the amount of deformation-induced to phase was maximum. Moreover, the magnetic susceptibility decreased with the deformation-induced beta -> omega to phase transformation, and the Zr-17Nb alloy with apparent kink bands exhibited a smaller amount of springback than the Zr-15Nb alloy with (3 3 2} (1 1 3) mechanical twins. Furthermore, the ions released from the Zr-xNb alloys in accelerated immersion tests were at a very low level. The combination of low initial Young's modulus, and its remarkable variation induced by deformation, low magnetic susceptibility, good ductility, and smaller springback make the Zr-17Nb alloy a potential candidate for spinal fixation rods.
  • Huihong Liu; Mitsuo Niinomi; Masaaki Nakai; Shinya Obara; Hidetoshi Fujii
    MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING ELSEVIER SCIENCE SA 704 10 - 17 0921-5093 2017/09 [Refereed]
     
    Oxygen was added into biomedical beta-type Ti-29Nb-13Ta-4.6Zr (mass%, TNTZ) alloy to improve its fatigue properties with maintaining its low Young's modulus. The effect of oxygen on the fatigue behaviors of these oxygen-added TNTZ alloys was systematically investigated. A series of TNTZ-(0.1, 0.3, 0.5 and 0.7 mass%)0 alloys were prepared, denoted as 0.10, 0.30, 0.50, and 0.70, respectively. The Young's moduli of the prepared alloys increase slightly with increasing oxygen content; 0.70 possessing the highest oxygen content still shows a quite low Young's modulus. The fatigue limits of the alloys increase monotonically with oxygen content increases. The high-concentration oxygen in 0.70 suppresses the slip plane decohesion and induces the formation of densely-arranged small-scaled alpha" martensite twins that increases the paths and distance for fatigue crack propagation, thus it enhances the resistance to the fatigue crack initiation and propagation in 0.70, which contributes to its excellent fatigue performance. Among all the alloys compared in the present study, 0.70 shows a high fatigue limit of similar to 635 MPa, a high tensile strength of similar to 1100 MPa, a large elongation of similar to 20% as well as a low Young's modulus of similar to 76 GPa, thus it is regarded as a promising biomaterial for next-generation biomedical applications.
  • 翠川裕; 仲井正昭; 新家光雄
    銅と銅合金 日本伸銅協会 56 (1) 318 - 322 1347-7234 2017/08 [Refereed]
  • Huihong Liu; Mitsuo Niinomi; Masaaki Nakai; Ken Cho; Hidetoshi Fujii
    SCRIPTA MATERIALIA PERGAMON-ELSEVIER SCIENCE LTD 130 27 - 31 1359-6462 2017/03 [Refereed]
     
    Deformation-induced co-phase transformation during tensile deformation was investigated in the developed spinal-support alloy, Ti-9Cr-0.2O. Both preferential single-variant omega transformation along its [0001] direction and growth and/or assembling of uniformly distributed omega particles undergo in the alloy during tensile deformation. It is confirmed that this deformation-induced omega-phase transformation can be triggered by elastic strain or stress without plastic deformation. Furthermore, a re-orientation process works for this transformation; that is, the omega(1) variant may re-orientate into the omega(2) variant via {001} (110) twinning-type mechanism probably related to the external loading condition and the orientations of omega and beta phases. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
  • P.F. Santos; M. Niinomi; H. Liu; M. Nakai; K. Cho; T. Narushima; K. Ueda; N. Ohtsu; M. Hirano; Y. Itoh
    Interface Oral Health Science 2016, Innovative Research on Biosis-Abiosis Intelligent Interface 229 - 245 2017/01 [Refereed]
  • Kentaro Niwa; Toshikazu Akahori; Mitsuo Niinomi; Tomokazu Hattori; Masaaki Nakai
    MATERIALS TRANSACTIONS JAPAN INST METALS 58 (6) 951 - 957 1345-9678 2017 [Refereed]
     
    In recent years, metallic biomaterial applications have demanded a relatively low Young s modulus that is nearly equal to that of bone (around 30 GPa). However, in the case of spinal fixture applications, metallic materials with a relatively high Young s modulus are required to suppress spring-back by elastic and plastic deformation during implantation. We recently proposed Young s modulus control by stress-induced transformation to produce the biomedical beta-type Ti-12Cr alloy. However, the relationship between the microstructure and the mechanical properties of Ti-12Cr has not been fully investigated. In this study, the changes in the mechanical properties of Ti-12Cr were investigated through the heat treatment and the fine particle bombarding process (FPB), which is a surface modification process. Peak aging (PA) of Ti-12Cr heated at 673 K occurred for around 2.4 ks. The Vickers hardness of Ti-12Cr at the PA condition at 673 K (HV 524) was around 90% higher than that after solutionized treatment (ST) (HV 294). Both the 0.2% proof stress and tensile strength of Ti-12Cr at the PA condition at 673 K were also around 50% higher those after ST. However, the ductility of Ti-12Cr at the PA condition at each temperature significantly decreased. Therefore, only ST was judged to be optimal for Ti-12Cr with an excellent combination of strength and ductility. The Vickers hardness and Young s modulus of solutionized Ti-12Cr subjected to FPB increased by around 40% and 70%, respectively, at the edge of the specimen surface compared with the corresponding values of the unprocessed sample. Furthermore, the run-out (770 MPa) of Ti-12Cr subjected to FPB increased by around 70 MPa. The bone contact ratio of Ti-12Cr slightly increased with an increase in the implantation period from 24 to 52 weeks.
  • Masaaki Nakai; Mitsuo Niinomi; Yu Ishida; Huihong Liu; Hidetoshi Fujii; Takashi Ninomiya
    MATERIALS TRANSACTIONS JAPAN INST METALS 58 (8) 1223 - 1226 1345-9678 2017 [Refereed]
     
    A post-weld heat treatment process, that is, solution treatment and aging, was found to be effective in improving the fatigue strength of friction stir welded Ti-6Al-4V butt joints. The stir-zone microstructure was changed by friction stir welding, from an equiaxed-a structure to a lamellar structure, but equiaxed-a structure remained in the base metal. Subsequently, solution treatment and aging modified these microstructures to bimodal structures in both the stir zone and base metal. The hardness in the stir zone differed from the base metal after friction stir welding, but the difference was eliminated by solution treatment and aging. The fatigue strength of friction stir welded Ti-6Al-4V butt joints was successfully increased by solution treatment and aging, which was higher than that of the parent Ti-6Al-4V plate. This indicates that solution treatment and aging increases the fatigue strength of friction stir welded Ti-6Al-4V butt joints by the formation of similar bimodal structures in the stir zone and base metal, resulting in reduced stress concentration at these boundaries and retarded fatigue failure.
  • Pedro Fernandes Santos; Mitsuo Niinomi; Ken Cho; Huihong Liu; Masaaki Nakai; Takayuki Narushima; Kyosuke Ueda; Yoshinori Itoh
    MATERIALS TRANSACTIONS JAPAN INST METALS 58 (2) 271 - 279 1345-9678 2017 [Refereed]
     
    Ti-Mn alloys fabricated by metal injection molding (MIM) show promising performance for biomedical applications, but their low ductility (caused by high O content and the presence of pores and carbides) requires improvement. Previously, the addition of Mo to cold crucible levitation melted (CCLM) Ti-Mn alloys efficiently improved the ductility of those alloys by promoting mechanical twinning. In the present study, Mo was added to Ti-Mn alloys fabricated by MIM. Unlike fabrication by CCLM, fabrication by MIM can produce alloys with a smaller grain size, and also introduce microstructures such as pores and Ti carbides. Thus, in order to investigate how Mo addition interacts with these typical MIM features, four alloys for biomedical applications were fabricated by MIM: Ti-5Mn-3Mo (TMM-53), Ti-5Mn-4Mo (TMM-54), Ti-6Mn-3Mo (TMM-63), and Ti-6Mn-4Mo (TMM-64). Their microstructures, mechanical properties, and tensile deformation mechanisms were evaluated. Their hardness values range from 312-359 HV, and their Young s modulus values range from 84-88 GPa; both the Vickers hardness and Young s modulus show little variation among the alloys. Although the alloys show fracture features associated with a predominantly ductile fracture mode and Mo addition successfully promotes mechanical twinning in TMM-54, the elongation of these alloys is still critically low. Compared to the TMM alloys fabricated by CCLM, the TMM alloys fabricated by MIM show slightly lower hardness and Young s modulus, and comparable tensile strength, with their low elongation remaining inadequate for such applications. In particular, TMM-63 shows the best combination of mechanical properties among the present alloys, with an elongation of 4% and an ultimate tensile strength of 1145 MPa.
  • Huihong Liu; Mitsuo Niinomi; Masaaki Nakai; Xin Cong; Ken Cho; Carl J. Boehlert; Vahid Khademi
    METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE SPRINGER 48A (1) 139 - 149 1073-5623 2017/01 [Refereed]
     
    Oxygen was added to the biomedical beta-type Ti-29Nb-13Ta-4.6Zr alloy (TNTZ, mass pct) in order to improve its strength, while keeping its Young's modulus low. Conventionally, with an increase in the oxygen content, an alloy's tensile strength increases, while its tensile elongation-to-failure decreases. However, an abnormal deformation behavior has been reported in the case of oxygen-modified TNTZ alloys in that their strength increases monotonically while their elongation-to-failure initially decreases and then increases with the increase in the oxygen content. In this study, this abnormal tensile deformation behavior of oxygen-modified TNTZ alloys was investigated systematically. A series of TNTZ-(0.1, 0.3, and 0.7 mass pct)O alloy samples was prepared, treated thermomechanically, and finally solution treated; these samples are denoted as 0.1ST, 0.3ST, and 0.7ST, respectively. The main tensile deformation mechanisms in 0.1ST are a deformation-induced alpha aEuro(3)-martensitic transformation and {332}aOE (c) 113 > mechanical twinning. The large elongation-to-failure of 0.1ST is attributable to multiple deformation mechanisms, including the deformation-induced martensitic transformation and mechanical twinning as well as dislocation glide. In both 0.3ST and 0.7ST, dislocation glide is the predominant deformation mode. 0.7ST shows more homogeneous and extensive dislocation glide along with multiple slip systems and a higher frequency of cross slip. As a result, it exhibits a higher work-hardening rate and greater resistance to local stress concentration, both of which contribute to its elongation-to-failure being greater than that of 0.3ST. (C) The Minerals, Metals & Materials Society and ASM International 2016
  • Hakan Yilmazer; Burak Dikici; Mitsuo Niinomi; Masaaki Nakai; Hui Houng Lui; Yoshikazu Todaka; Ahmet Nuri Ozcivan
    Materials Science Forum Trans Tech Publications, Ltd. 879 2549 - 2554 0255-5476 2016/11 [Refereed]
     
    The microstructural evolution and its effect on biocompatibility of TNTZ through HPT processing were investigated systematically in this study. TNTZAHPT shows an enhanced mechanical biocompatibility, which is characterized by a higher tensile strength (1375 MPa) and hardness (450 HV) than those of TNTZST, TNTZAT, and Ti64 ELI while maintaining a relatively low Young’s modulus. In this study, such microstructural refinement of TNTZ and its effect on electrochemical biocompatibility through HPT processing are investigated systematically in this study. The microstructure of TNTZAT consists of randomly distributed needle-like α precipitates in the equiaxed β grains with a diameter of approximately 40 m. The microstructure of TNTZAHPT consists of nanograined (NG) elongated β grains that have subgrains of non-uniform morphologies resulting from distortion by severe torsional deformation. Furthermore, the β grains and subgrains are surrounded by non-equilibrium grain boundaries. The needle-like α precipitates are completely refined to a nanograined. TNTZAHPT exhibits an enhanced combination of excellent corrosion performance and improved cellular response compared to TNTZST, TNTZAT, and Ti64 ELI.
  • Osamu Takakuwa; Masaaki Nakai; Kengo Narita; Mitsuo Niinomi; Kazuhiro Hasegawa; Hitoshi Soyama
    INTERNATIONAL JOURNAL OF FATIGUE ELSEVIER SCI LTD 92 360 - 367 0142-1123 2016/11 [Refereed]
     
    The surface treatment technology known as 'cavitation peening' was employed in this study in order to enhance the durability of spinal implant fixture applications, which are subject to fretting fatigue. Cavitation peening can be realized by a technique in which a high-speed water jet is injected into water through a nozzle. It utilizes a phenomenon by which surface impacts due to collapsing cavitation bubbles induce work-hardening by introducing residual compressive stress near the surface. A fretting fatigue test was conducted on a spinal implant rod made of Ti-6Al-4V ELI in accordance with the ASTM F1717 standard, which is the established method for testing spinal implants after they are treated by cavitation peening. The residual stress was evaluated by using X-ray diffraction analysis. The hardness over the cross-sectional area was also measured using an indentation test. The obtained results show that cavitation peening drastically improves the fretting fatigue properties of spinal implant fixtures by as much as 2.2 times compared to untreated ones. This can be attributed to a significant increase in the hardness from 5.0 to 9.6 GPa and a high compressive residual stress of over 600 MPa induced by cavitation peening. (C) 2016 Elsevier Ltd. All rights reserved.
  • Pedro Fernandes Santos; Mitsuo Niinomi; Huihong Liu; Ken Cho; Masaaki Nakai; Adhitya Trenggono; Sebastien Champagne; Hendra Hermawan; Takayuki Narushima
    MATERIALS & DESIGN ELSEVIER SCI LTD 110 414 - 424 0264-1275 2016/11 [Refereed]
     
    In previous studies, Ti-Mn alloys showed promising performance for biomedical applications, but their elongation required improvement. In this study, Mo was added to Ti-Mn alloys to promote mechanical twinning and improve their ductility. Four alloys for biomedical applications were designed and fabricated by cold crucible levitation melting: Ti-5Mn-3Mo (TMM-53), Ti-5Mn-4Mo (TMM-54), Ti-6Mn-3Mo (TMM-63), and Ti-6Mn-4Mo (TMM-64). The microstructure, mechanical properties, tensile deformation mechanisms, and electrochemical corrosion properties of the alloys were evaluated. Their hardness ranges from 336 to 373 HV. Their Young's modulus ranges from 89 to 100 GPa. Both hardness and Young's modulus tend to decrease with decreasing amount of athermal omega phase, which is caused by increasing alloying elements contents. Mo addition improves the elongation of TMM-53 and TMM-54 by promoting twinning. Conversely, it increases the tensile strength of TMM-63 and TMM-64. Particularly, TMM-54 shows an elongation of 34% with an ultimate tensile strength (UTS) of 935 MPa. TMM-63 shows an elongation of 14% and a UTS of 1220 MPa, associated to the formation of deformation-induced to phase. Moreover, Mo addition decreases the corrosion rate of the Ti-Mn alloys to a level comparable to that of commercially-pure Ti. (C) 2016 Elsevier Ltd. All rights reserved.
  • Mitsuo Niinomi; Masaaki Nakai; Mandana Hendrickson; Peeyush Nandwana; Talukder Alam; Deep Choudhuri; Rajarshi Banerjee
    SCRIPTA MATERIALIA PERGAMON-ELSEVIER SCIENCE LTD 123 144 - 148 1359-6462 2016/10 [Refereed]
     
    The effect of oxygen on stability of isothermal omega precipitates in Ti-29Nb-13Ta-4.6Zr was examined using Xray powder diffraction, transmission electron microscopy, and atom probe tomography. Two alloys with 0.1 and 0.4 mass% oxygen were subjected to single step, and two-step annealing heat-treatments to respectively promote omega and alpha formation. After second step annealing, large volume fraction of omega precipitates was retained in 0.4 mass% 0 alloy while mainly alpha phase was observed in TNTZ-0.10. The enhanced stability of omega in the higher oxygen containing TNTZ alloys questions the conventionally accepted understanding that oxygen destabilizes the omega phase in titanium alloys. (C) 2016 Elsevier Ltd. All rights reserved.
  • M. Niinomi; Y. Liu; M. Nakai; H.H. Liu; H. Li
    Regenerative Biomaterials 3 (3) 173 - 185 2016/09 [Refereed]
  • 翠川裕; 仲井正昭; 翠川薫; 新家光雄
    銅と銅合金 日本伸銅協会 55 (1) 86 - 88 1347-7234 2016/08 [Refereed]
  • E. Takematsu; K. Cho; J. Hieda; M. Nakai; K. Katsumata; K. Okada; M. Niinomi; N. Matsushita
    JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS ELSEVIER SCIENCE BV 61 174 - 181 1751-6161 2016/08 [Refereed]
     
    Bioactive oxide layers were fabricated on Ti-29Nb-13Ta-4.6Zr alloy (TNTZ) by three different alkali solution treatments: hydrothermal (H), electrochemical (E), and hydro thermal -electrochemical (HE). The adhesive strength of the oxide layer to the TNTZ substrate was measured to determine whether this process achieves sufficient adhesive strength for implant materials. Samples subjected to the HE process, in which a current of 15 mA/cm(2) was applied at 90 degrees C for 1 h (HE90-1h), exhibited a comparatively higher adhesive strength of approximately 18 MPa while still maintaining a sufficiently high bioactivity. Based on these results, an oxide layer fabricated on TNTZ by HE90-1h is considered appropriate for practical biomaterial application, though thicker oxide layers with many cracks can lead to a reduced adhesive strength. (C) 2016 Elsevier Ltd. All rights reserved.
  • 生体適合性Ti-Nb-Ta-Zr合金の超音波疲労特性
    山浦真一; 成田健吾; 仲井正昭; 新家光雄
    材料の科学と工学 53 (4) 126 - 131 2016/08 [Refereed]
  • Yun-Fei Ding; Rachel W. Li; Masaaki Nakai; Trina Majumdar; Dong-Hai Zhang; Mitsuo Niinomi; Nick Birbilis; Paul N. Smith; Xiao-Bo Chen
    ADVANCED HEALTHCARE MATERIALS WILEY-BLACKWELL 5 (14) 1740 - 1752 2192-2640 2016/07 [Refereed]
     
    Osteoporosis is becoming more prevalent due to the aging demographics of many populations. Osteoporotic bone is more prone to fracture than normal bone, and current orthopedic implant materials are not ideal for the osteoporotic cases. A newly developed strontium phosphate (SrPO4) coating is reported herein, and applied to Ti-29Nb-13Ta-4.6Zr (wt%), TNTZ, an implant material with a comparative Young's modulus to that of natural bone. The SrPO4 coating is anticipated to modulate the activity of osteoblast (OB) and osteoclast (OC) cells, in order to promote bone formation. TNTZ, a material with excellent biocompatibility and high bioinertness is pretreated in a concentrated alkaline solution under hydrothermal conditions, followed by a hydrothermal coating growth process to achieve complete SrPO4 surface coverage with high bonding strength. Owing to the release of Sr ions from the SrPO4 coating and its unique surface topography, OB cells demonstrate increased proliferation and differentiation, while the cellular responses of OC are suppressed, compared to the control case, i.e., bare TNTZ. This TNTZ implant with a near physiologic Young's modulus and a functional SrPO4 coating provides a new direction in the design and manufacture of implantable devices used in the management of orthopedic conditions in osteoporotic individuals.
  • Pedro Fernandes Santos; Mitsuo Niinomi; Huihong Liu; Ken Cho; Masaaki Nakai; Yoshinori Itoh; Takayuki Narushima; Masahiko Ikeda
    JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS ELSEVIER SCIENCE BV 59 497 - 507 1751-6161 2016/06 [Refereed]
     
    Titanium and its alloys are suitable for biomedical applications owing to their good mechanical properties and biocompatibility. Beta-type Ti-Mn alloys (8-17 mass% Mn) were fabricated by metal injection molding (MIM) as a potential low cost material for use in biomedical applications. The microstructures and mechanical properties of the alloys were evaluated. For up to 13 mass% Mn, the tensile strength (1162-938 MPa) and hardness (308-294 HV) of the MIM fabricated alloys are comparable to those of Ti-Mn alloys fabricated by cold crucible levitation melting. Ti-9Mn exhibits the best balance of ultimate tensile strength (1046 MPa) and elongation (4.7%) among the tested alloys, and has a Young's modulus of 89 GPa. The observed low elongation of the alloys is attributed to the combined effects of high oxygen content, with the presence of interconnected pores and titanium carbides, the formation of which is due to carbon pickup during the debinding process. The elongation and tensile strength of the alloys decrease with increasing Mn content. The Ti-Mn alloys show good compressive properties, with Ti-17Mn showing a compressive 0.2% proof stress of 1034 MPa, and a compressive strain of 50%. (C) 2016 Elsevier Ltd. All rights reserved.
  • Murat Isik; Mitsuo Niinomi; Ken Cho; Masaaki Nakai; Huihong Liu; Hakan Yilmazer; Zenji Horita; Shigeo Sato; Takayuki Narushima
    JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS ELSEVIER SCIENCE BV 59 226 - 235 1751-6161 2016/06 [Refereed]
     
    The effects of severe plastic deformation through high-pressure torsion (HPT) on the microstructure and tensile properties of a biomedical Co-Cr-Mo (CCM) alloy were investigated. The microstructure was examined as a function of torsional rotation number, N and equivalent strain, epsilon(eq) in the HPT processing. Electron backscatter diffraction analysis (EBSD) shows that a strain-induced martensitic transformation occurs by the HPT processing. Grain diameter decreases with increasing epsilon(eq), and the HPT-processed alloy (CCMHPT)for epsilon(eq)=45 exhibits an average grain diameter of 47 nm, compared to 70 mu m for the CCM alloy before HPT processing. Blurred and wavy grain boundaries with low-angle of misorientation in the CCMHPT sample for epsilon(eq) <45 become better-defined grain boundaries with high-angle of misorientation after HPT processing for epsilon(eq)=45. Kernel average misorientation (KAM) maps from EBSD indicate that KAM inside grains increases with epsilon(eq) for epsilon(eq)<45, and then decreases for epsilon(eq)=45. The volume fraction of the epsilon (hcp) phase in the CCMHPT samples slightly increases at epsilon(eq)=9, and decreases at epsilon(eq)=45. In addition, the strength of the CCM samples increases at epsilon(eq)=9, and then decrease at epsilon(eq)=45. The decrease in the strength is attributed to the decrease in the volume fraction of e phase, annihilation of dislocations, and decrease in strain in the CCMHPT sample processed at epsilon(eq)=45 by HPT. () 2015 Elsevier Ltd. All rights reserved.
  • Hakan Yilmazer; Mtsuo Niinomi; Ken Cho; Masaaki Nakai; Huihoung Lui; Yoshikazu Todaka; Burak Dikici; Mustafa Şen; Hitoshi Shiku; Tomokazu Matsue
    Proceedings of the 13th World Conference on Titanium John Wiley & Sons, Inc. 1761 - 1766 2016/05 [Refereed]
  • Development of New Ti-Mn-Mo Alloys for Use in Biomedical Applications
    P.F. Santos; M. Niinomi; K. Cho; M. Nakai; H.H. Liu
    Proceedings of the 13th World Conference on Titanium 1741 - 1745 2016/05 [Refereed]
  • A β-Type Titanium Alloy With Significantly Changeable Young’S Modulus and Good Mechanical Properties Used for Spinal Fixation Applications
    H.H. Liu; M. Niinomi; M. Nakai; K. Cho; K. Narita
    Proceedings of the 13th World Conference on Titanium 1685 - 1689 2016/05 [Refereed]
  • Tensile and Compressive Properties of Low-Cost High-Strength β-Type Ti-Mn Alloys Fabricated by Metal Injection Molding
    K. Cho; M. Niinomi; M. Nakai; H.H. Liu; P.F. Santos; Y. Itoh; M. Ikeda
    Proceedings of the 13th World Conference on Titanium 499 - 503 2016/05 [Refereed]
  • Wear Behaviors of Combinations Comprised of Titanium Alloys in Air and Ringer’S Solution
    M. Nakai; M. Niinomi; K. Narita; K. Cho; H.H Liu; Y.S. Lee
    Proceedings of the 13th World Conference on Titanium 1707 - 1710 2016/05 [Refereed]
  • Development of Biomedical Titanium Alloys with a Focus on Controlling Young’s Modulus
    M. Niinomi; M. Nakai; H.H. Liu; K. Cho
    Proceedings of the 13th World Conference on Titanium 1655 - 1663 2016/05 [Refereed]
  • M. Sato; O. Takakuwa; M. Nakai; M. Niinomi; F. Takeo; H. Soyama
    Mater. Sci. Appl. 7 (4) 181 - 191 2016/04 [Refereed]
  • Oribe Kazuya; Hasegawa Kazuhiro; Kitahara Kou; Tamura Takashi; Narita Kengo; Yamanaka Shigeru; Nakai Masaaki; Takakuda Kazuo; Niinomi Mitsuo
    Materia Japan 公益社団法人 日本金属学会 55 (4) 142 - 146 1340-2625 2016/04
  • Yusuke Tsutsumi; Mitsuo Niinomi; Masaaki Nakai; Masaya Shimabukuro; Maki Ashida; Peng Chen; Hisashi Doi; Takao Hanawa
    METALS MDPI 6 (4) Article ID 76  2075-4701 2016/04 [Refereed]
     
    In this study, micro-arc oxidation (MAO) was performed on a beta-type titanium alloy, namely, Ti-29Nb-13Ta-4.6Zr alloy (TNTZ), to improve not only its antibacterial property but also bioactivity in body fluids. The surface oxide layer formed on TNTZ by MAO treatment in a mixture of calcium glycerophosphate, calcium acetate, and silver nitrate was characterized using surface analyses. The resulting porous oxide layer was mainly composed of titanium oxide, and it also contained calcium, phosphorus, and a small amount of silver, all of which were incorporated from the electrolyte during the treatment. The MAO-treated TNTZ showed a strong inhibition effect on anaerobic Gram-negative bacteria when the electrolyte contained more than 0.5 mM silver ions. The formation of calcium phosphate on the surface of the specimens after immersion in Hanks' solution was evaluated to determine the bioactivity of TNTZ with sufficient antibacterial property. As a result, thick calcium phosphate layers formed on the TNTZ specimen that underwent MAO treatment, whereas no precipitate was observed on TNTZ without treatment. Thus, the MAO treatment of titanium-based alloys is confirmed to be effective in realizing both antibacterial and bioactive properties.
  • Ken Cho; Mitsuo Niinomi; Masaaki Nakai; Huihong Liu; Pedro F. Santos; Yoshinori Itoh; Masahiko Ikeda; Mohamed Abdel-Hady Gepreel; Takayuki Narushima
    JOURNAL OF ALLOYS AND COMPOUNDS ELSEVIER SCIENCE SA 664 272 - 283 0925-8388 2016/04 [Refereed]
     
    In order to develop new low-cost and high-strength beta-type titanium alloys, a Ti-13Mn was fabricated by metal injection molding. For improving its tensile strength, Ti-13Mn was subjected to cold-rolling at reduction ratios of 60% and 90%, respectively. The solutionized Ti-13Mn has pores and titanium carbide (Ti carbide) precipitates and consists of a beta phase and an athermal omega phase. The porosity of the alloy decreases from 6.1% to 0.01% after cold-rolling at a reduction ratio of 90%. Moreover, during cold-rolling, the Ti carbides are fragmented and a deformation-induced omega phase is formed. The ultimate tensile strength, 0.2% proof stress, Vickers hardness, and Young's modulus of Ti-13Mn increase from 888 MPa to 1852 MPa, from 827 MPa to 1823 MPa, from 279 Hv to 461 Hv, and from 96 GPa to 108 GPa, respectively, after cold-rolling at a reduction ratio of 90%. On the other hand, the elongations of both the solutionized and cold rolled Ti-13Mn are less than 2%. Although the elongation of Ti-13Mn is less than 2%, the tensile strength of the cold rolled Ti-13Mn is extremely high compared with that of existing titanium alloys. This large-improvement in the tensile strength of the cold rolled Ti-13Mn is attributed to the increase in the dislocation density, decrease in grain size, decrease in porosity, and formation of a deformation-induced omega phase. (c) 2015 Elsevier B.V. All rights reserved.
  • Yutaka Midorikawa; Masaaki Nakai; Kaoru Midorikawa; Mitsuo Niinomi
    JOURNAL OF THE JAPAN INSTITUTE OF METALS JAPAN INST METALS 80 (3) 165 - 170 0021-4876 2016/03 [Refereed]
     
    A novel method for detecting antimicrobial activity using an innate property of the Salmonella bacteria, namely, the ability of Salmonella to produce hydrogen sulfide (H2S) was developed in this study. The effectiveness of the method was evaluated by comparing the antibacterial activity of copper to that of aluminum. Salmonella was inoculated over the entire surface of deoxycholate hydrogen sulfide lactose (DHL) agar plates that included Ammonium ferric citrate (C6H8FeN). Approximately 251 mu L, of cupric chloride (CuCl2, 1% weight ratio) solution or aluminum chloride (AlCl3, 1% weight ratio) solution was added to the center of the medium. The surface of the medium was covered with plastic PET (polyethylene terephthalate) material to induce an anaerobic state. Salmonella was cultured under anaerobic conditions at 310 K (37 degrees C) for 86.4 ks (24 h). The antibacterial activity of copper was determined by observing the medium surface color change due to iron sulfide (FeS) formation, which was caused by the production of H2S by Salmonella; blackness indicated presence of newly formed FeS. A quantitative evaluation of copper's antimicrobial activity was performed using a gradient of CuCl2 concentrations; results were compared with those of the present standard method, Kirby-Bauer disk diffusion method on the Mueller Hinton medium. Finally, in order to evaluate the antibacterial activity of metals, Salmonella was inoculated on DHL agar plates. Subsequently, Japanese coins (1 yen, 5 yen, 10 yen, 50 yen, 100 yen and 500 yen coins) were placed on the agar and cultured at 310 K for 86 ks. Salmonella cultured in the presence of AlCl3 produces black color, while no blackening is observed with CuCl2, suggesting that copper possesses an antibacterial property against Salmonella. CuCl2 suppresses H2S production by Salmonella, as Cu2+ forms a transparent circle or ellipse (new halo) around the point at which CuCl2 had has been plated. The size of the new halo increases in direct proportion to the concentration of CuCl2. The halo is no longer visible at 0.034 mg of CuCl2 in our method, while the halo disappears with 4.34 mg of CuCl2 in the Kirby-Bauer method. Therefore, the present method is 129 times more sensitive than the standard method, suggesting increased usefulness and effectiveness in testing antibacterial activity. No FeS-dependent black circle is formed under any of the coins, with the exception of the 1-yen coin, which contains aluminum and no copper. Therefore, the copper-containing coins have an antibacterial effect.
  • Huihong Liu; Mitsuo Niinomi; Masaaki Nakai; Ken Cho
    ACTA MATERIALIA PERGAMON-ELSEVIER SCIENCE LTD 106 162 - 170 1359-6454 2016/03 [Refereed]
     
    The alloy Ti-9Cr-0.20 has been developed as a potential material for implant rods used in spinal fixation applications, since it exhibits good mechanical properties and a remarkably "changeable Young's modulus", which is achieved by suppressing the athermal omega-phase formed upon quenching and enhancing the deformation-induced omega-phase transformation. In this study, athermal and deformation induced omega-phase transformations in Ti-9Cr-0.20 were investigated systematically by transmission electron microscopy. This was done in order to understand the nature of these omega-phase transformations, as well as the specific functionality the "changeable Young's modulus" resulting from them. In solution-treated alloy samples, in addition to ideal omega-structures, structures considered as initial omega-structures associated with incommensurate omega-phase were observed. This might be attributed to the composition heterogeneity, heterogeneity of oxygen distribution, and/or the inhomogeneous distribution of defects such as vacancies and locally strained areas. Following cold rolling, some of the selected area electron diffraction patterns of the alloy showed that the reflections of one omega-variant had increased significantly in intensity while those of the other omega-variant had decreased sharply. This vanishing of one type of variant omega-structures is attributable to two possible mechanisms: (i) a reversal mechanism, under which the particular < 111 > partial dislocations transform the corresponding omega-variants back into beta-phase or (ii) a re-orientation mechanism, according to which the omega-variants unfavorable with regard to the loading direction re-orient and turn into the preferred omega-variants. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
  • Mitsuo Niinomi; Masaaki Nakai; Huihong Liu; Kengo Narita
    TMS Annual Meeting 215 - 221 2016/01 
    Ti-12Cr has been developed for use in various biomedical applications, in particular; it is expected to be used for the rods of the spinal fixation devices. When Ti-12Cr is deformed, its Young's modulus increases because of deformation-induced ω phase transformation. If a spinal rod made of Ti-12Cr is bent during operation, only the Young's modulus of the bent region will increase; this phenomenon decreases the springback of the rod so that the bent shape is maintained. The compression fatigue strength of Ti-12Cr obtained from compression fatigue tests performed according to ASTM F1717 can be significantly improved by cavitation peening. Details of the development of this Ti-Cr alloy for use as spinal rods are discussed.
  • Hakan Yilmazer; Mustafa Sen; Mitsuo Niinomi; Masaaki Nakai; Liu Huihong; Ken Cho; Yoshikazu Todaka; Hitoshi Shiku; Tomokazu Matsue
    RSC ADVANCES ROYAL SOC CHEMISTRY 6 (9) 7426 - 7430 2046-2069 2016 [Refereed]
     
    Proper surface characteristics for a titanium implant are crucial for the formation of different cellular protrusions known as filopodia and lamellipodia, both of which have a significant impact on cell attachment, spreading, migration, and proliferation. Microstructural features such as grain boundaries and defects of implant surface can modulate the cellular components and structure at the leading edge of cells. Here, a nano-grained Ti-29Nb-13Ta-4.6Zr (NG TNTZ) substrate was produced by high-pressure torsion (HPT) for improved biofunctionality. Cellular response of human osteoblast cells on nano-grained TNTZ substrates is evaluated and compared with the cellular response of those on coarse-grained TNTZ. High wettability, which depends on high internal energy due to the nano-sized grains that are full of boundaries, interfaces, and high dislocation density, influenced the hOBs cells on NG TNTZ to form highly developed cellular protrusions. Large number of filopodia protrusions resulted in excellent cell attachment as consistent with high level of vinculin and superior cell proliferation. This study demonstrates the advantages of nanocrystalline surface modification using HPT for processingmetallic biomaterials that are proper for orthopedic implants.
  • Yutaka Midorikawa; Masaaki Nakai; Kaoru Midorikawa; Mitsuo Niinomi
    MATERIALS TRANSACTIONS JAPAN INST METALS 57 (6) 995 - 1000 1345-9678 2016 [Refereed]
     
    A novel method for detecting antimicrobial activity using an innate property of the Salmonella bacteria, namely, the ability of Salmonella to produce hydrogen sulfide (H2S) was developed in this study. The validity of the method was evaluated by comparing the antibacterial activity of copper to that of aluminum. Salmonella was inoculated over the entire surface of deoxycholate hydrogen sulfide lactose (DHL) agar plates that included Ammonium ferric citrate (C6H8FeN). Approximately 25 mu L of cupric chloride (CuCl2, 1% weight ratio) solution or aluminum chloride (AlCl3, 1% weight ratio) solution was added to the center of the medium. The surface of the medium was covered with polyethylene terephthalate (PET) films to induce an anaerobic state. Salmonella was cultured under anaerobic conditions at 310 K (37 degrees C) for 86.4 ksec (24 h). The antibacterial activity of copper was determined by observing the medium surface color change due to iron sulfide (FeS) formation, which was caused by the production of H2S by Salmonella; blackness indicated presence of newly formed FeS. A quantitative evaluation of copper's antimicrobial activity was performed using a gradient of CuCl2 concentrations; results were compared with those of the present standard method, Kirby-Bauer disk diffusion method on the Mueller Hinton medium. Finally, in order to evaluate the antibacterial activity of metals, Salmonella was inoculated on DHL agar plates. Subsequently, Japanese coins (1-yen, 5-yen, 10-yen, 50-yen, 100-yen, and 500-yen coins) were placed on the agar and cultured at 310 K for 86 ksec. Salmonella cultured in the presence of AlCl3 produces black color, while no blackening is observed with CuCl2, suggesting that copper possesses an antibacterial property against Salmonella. CuCl2 suppresses H2S production by Salmonella, as copper ions form a transparent circle or ellipse (new halo) around the point at which CuCl2 had has been plated. The size of the new halo increases in direct proportion to the concentration of CuCl2. The halo is no longer visible at 0.034 mg of CuCl2 in our method, while the halo disappears with 4.34 mg of CuCl2 in the Kirby-Bauer test. Therefore, the present method is 129 times more sensitive than the standard method, suggesting increased usefulness and effectiveness in testing antibacterial activity. No FeS-dependent black circle is formed under any of the coins, with the exception of the 1-yen coin, which contains aluminum and no copper. Therefore, the copper-containing coins have an antibacterial effect.
  • Murat Isik; Mitsuo Niinomi; Huihong Liu; Ken Cho; Masaaki Nakai; Zenji Horita; Takayuki Narushima; Kyosuke Ueda
    MATERIALS TRANSACTIONS JAPAN INST METALS 57 (11) 1887 - 1896 1345-9678 2016 [Refereed]
     
    The main target of this study is to optimize the microstructure and to achieve an optimization for the mechanical properties in a biomedical Co-Cr-Mo (CCM) alloy with the nominal composition of Co-28Cr-6Mo (mass%) subjected to high-pressure torsion (HPT) and subsequent short annealing. The gamma ->epsilon phase transformation and grain refinement occur in the CCM alloy subjected to HPT processing at an equivalent strain (epsilon(eq)) of 2.25 (CCMHPT). The HPT processing causes a decrease in the elongation due to the formation of an excessive amount of epsilon phase. For removal of the excessive amount of e phases, the CCMHPT was subjected to a short annealing (CCMHPTA). The effect of the short annealing temperature (1073 K, 1273 K, and 1473 K; annealing time was fixed at 0.3 ks) on CCMHPT was investigated. In addition, the effect of the length of duration for the short annealing (0.06 ks, 0.3 ks, and 0.6 ks;) for a fixed annealing temperature of 1273 K on CCMHPT was studied. CCMHPTA(1273 K) annealed for 0.3 ks shows a good optimization of mechanical properties that include high strength and large elongation owing to its ultra fine-grained microstructure, and removal of excessive e phases.
  • Kentaro Niwa; Toshikazu Akahori; Mitsuo Niinomi; Tomokazu Hattori; Masaaki Nakai
    JOURNAL OF THE JAPAN INSTITUTE OF METALS JAPAN INST METALS 80 (12) 764 - 771 0021-4876 2016 [Refereed]
     
    In recent years, metallic biomaterial applications have demanded a relatively low elastic modulus of around 30 GPa that is nearly equal to that of bone. However, in the case of spinal fixture applications, metallic materials with a relatively high Young's modulus are required to suppress spring-back by elastic and plastic deformation during implantation. Therefore, Young's modulus control by stress-induced transformation in a newly developed biomedical beta-type Ti-12Cr alloy, has been proposed by the present authors. However, the relationship between the microstructure and mechanical properties of Ti-12Cr has not been fully investigated up till now. Therefore, changes in the mechanical properties of Ti-12Cr were investigated through heat treatment and the fine particle bombarding process (FPB), which is a surface modification process used in this study. Peak aging of Ti-12Cr heated at 673 K showed for around 2.4 ks. The Vickers hardness of Ti-12Cr in the peak aging condition (PA) at 673 K was around 90% (HV 524) higher than that (HV 294) in the solutionized condition (ST). Meanwhile, both the 0.2% proof stress and tensile strength of Ti-12Cr in the PA at 673 K were also around 50% higher those in the ST. However, the ductility of Ti-12Cr in the PA at each temperature reduced significantly. Therefore, a solo-solution treatment was judged to be the optimal heat treatment for Ti-12Cr with an excellent combination of strength and ductility. The Vickers hardness and Young's modulus of as. solutionized Ti-12Cr subjected to FPB increased by around 40% and 70%, respectively, at the very edge of the specimen surface, as compared to those of the unprocessed sample. Furthermore, the fatigue strength of Ti-12Cr subjected to FPB increased by around 70 MPa. The bone contact ratio of Ti-12Cr rose slightly with an increase in the implantation period from 24 to 52 weeks.
  • Yoon-Seok Lee; Mitsuo Niinomi; Masaaki Nakai; Kengo Narita; Huihong Liu
    MATERIALS TRANSACTIONS JAPAN INST METALS 57 (12) 1993 - 1997 1345-9678 2016 [Refereed]
     
    In spinal fixation devices, the activity of the patient can cause fretting of the metal-to-metal contacts between the rod and plug, which may result in failures. In this study, compressive fatigue tests were conducted with rods made of Ti-29Nb-13Ta-4.6Zr alloy (TNTZ) with oxygen contents of 0.06 mass% (06O) and 0.89 mass% (89O) and Ti-6Al-4V extra low interstitial alloy (Ti64) as comparison in both air and saline solution. The fatigue strength increases in the order of 06O < 89O < Ti64 in both air and saline solution. These results indicate that solid-solution strengthening by oxygen improves the fretting fatigue resistance of the TNTZ rod.
  • Murat Isik; Mitsuo Niinomi; Huihong Liu; Ken Cho; Masaaki Nakai; Zenji Horita; Shigeo Sato; Takayuki Narushima; Hakan Yilmazer; Makoto Nagasako
    MATERIALS TRANSACTIONS JAPAN INST METALS 57 (7) 1109 - 1118 1345-9678 2016 [Refereed]
     
    Ultrafine-grained materials often possess superior mechanical properties owing to their small grain size. The high-pressure torsion (IIPT) process is a severe plastic deformation method used to induce ultra-large strain and produce ultrafine grains. In this study, the grain refinement mechanisms in the Co-28Cr-6Mo (CCM) alloy, evolution of dislocation density as a result of HPT and its effects on mechanical properties were investigated. The dislocation density and subgrain diameter were also calculated by X-ray line profile analysis. The microstructure of the CCM alloy subjected to HPT processing (CCMHPT) was evaluated as a function of torsional rotation number, N and equivalent strain, epsilon(eq). Strain-induced gamma ->epsilon transformation in neighboring ultrafine grains is observed in CCMHPT processed at epsilon(eq) = 2.25 and epsilon(eq) = 4.5. Low-angle crystal rotation around the [110] fcc direction occurs in different locations in the same elongated grain neighboring ultrafine grains, which suggests the formation of low-angle grain boundaries in CCMHPT processed at epsilon(eq) = 2.25 and epsilon(eq) = 4.5. Two possible grain refinement mechanisms are proposed. The maximum dislocation densities, which are 2.8 x 10(16) m(-2) in gamma phase and 3.8 x 10(16) m(-2) in epsilon phase, and maximum subgrain diameters, which are 21.2 nm in gamma phase and 36 nm in epsilon phase, are achieved in CCMHPT processed at epsilon(eq) = 9. IIPT processing causes a substantial increase in the tensile strength and hardness owing to the grain refinement and a significant increase in the volume fraction of epsilon phase and dislocation density.
  • Design, microstructural characterization and mechanical evaluation of novel Ti-Mn-Mo alloys for biomedical applications
    P.F. Santos; M. Niinomi; H. Liu; M. Nakai; K. Cho; T. Narushima
    Proceedings of the 24th International Symposium on Processing and Fabrication of Advanced Materials, PFAM XXIV 120 - 125 2015/12 [Refereed]
  • Microstructure and balanced mechanical properties of short-time solution treated Co-Cr-Mo alloys processed through high-pressure torsion
    M. Isik; M. Niinomi; H. Liu; M. Nakai; K. Cho; Z. Horita; T. Narushima
    Proceedings of the 24th International Symposium on Processing and Fabrication of Advanced Materials, PFAM XXIV 680 - 685 2015/12 [Refereed]
  • Yoon-Seok Lee; Mitsuo Niinomi; Masaaki Nakai; Kengo Narita; Ken Cho; Huihong Liu
    JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS ELSEVIER SCIENCE BV 51 398 - 408 1751-6161 2015/11 [Refereed]
     
    In previous studies, it has been concluded that volume losses (V-loss) of the Ti-29Nb-13Ta-4.6Zr (TNTZ) discs and balls are larger than those of the respective Ti-6Al-4V extra-low interstitial (Ti64) discs and balls, both in air and Ringer's solution. These results are related to severe subsurface deformation of TNTZ, which is caused by the lower resistance to plastic shearing of TNTZ than that of Ti64. Therefore, it is necessary to further increase the wear resistance of TNTZ to satisfy the requirements as a biomedical implant. From this viewpoint, interstitial oxygen was added to TNTZ to improve the plastic shear resistance via solid-solution strengthening. Thus, the wear behaviors of combinations comprised of a new titanium alloy, TNTZ with high oxygen content of 0.89 mass% (890) and a conventional titanium alloy, Ti64 were investigated in air and Ringer's solution for biomedical implant applications. The worn surfaces, wear debris, and subsurface damage were analyzed using a scanning electron microscopy and an electron probe microanalysis. V-loss of the 890 discs and balls are smaller than those of the respective TNTZ discs and balls in both air and Ringer's solution. It can be concluded that the solid-solution strengthening by oxygen effectively improves the wear resistance for TNTZ materials. However, the 890 disc/ball combination still exhibits higher V-loss than the Ti64 disc./ball combination in both air and Ringer's solution. Moreover, V-loss of the disc for the 890 disc/Ti64 ball combination significantly decreases in Ringer's solution compared to that in air. This decrease for the 890 disc./Ti64 ball combination in Ringer's solution can be explained by the transition in the wear mechanism from severe delamination wear to abrasive wear. (C) 2015 Elsevier Ltd. All rights reserved.
  • Pedro Fernandes Santos; Mitsuo Niinomi; Ken Cho; Masaaki Nakai; Huihong Liu; Naofumi Ohtsu; Mitsuhiro Hirano; Masahiko Ikeda; Takayuki Narushima
    ACTA BIOMATERIALIA ELSEVIER SCI LTD 26 366 - 376 1742-7061 2015/10 [Refereed]
     
    The microstructures, mechanical properties and biocompatibility of low cost beta-type Ti-(6-18)Mn alloys were investigated after solution treatment. Ti-9Mn exhibits the best combination of tensile strength and elongation among the fabricated alloys, and its performance is comparable to or superior to those of Ti-6Al-4V ELI (Ti-64 ELI) in terms of every parameter evaluated. A hardness of 338 HV, a Young's modulus of 94 GPa, a 0.2% proof stress of 1023 MPa, an ultimate tensile strength of 1048 MPa and elongation of 19% were obtained for Ti-9Mn. Furthermore, the cell viability and metallic ion release ratios are comparable to those of commercially pure titanium, making this alloy promising for biomedical applications. The Young's modulus is also lower than that of Ti-64 ELI (110 GPa), which can possibly reduce the stress shielding effect in implanted patients. Statement of significance This study evaluates mechanical and biological performance of low cost solution treated beta-type Ti-(6, 9, 13 and 18 mass%)Mn alloys. It includes alloys containing a Mn content range higher than most previously published works (which is around or lower than 8 mass%). Furthermore, the effects of the omega phase and the beta phase stability of the alloys over some mechanical properties and microstructures are discussed. Ion release behavior under simulated body fluids and cell viability are also evaluated. For the case of the Ti-9Mn, a mechanical and biological performance that is comparable to or superior than that of the widely used Ti-6Al-4V ELI and commercially pure Ti was observed. (C) 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
  • Junko Hieda; Mitsuo Niinomi; Masaaki Nakai; Ken Cho; Ayaka Matsubara
    MATERIALS TRANSACTIONS JAPAN INST METALS 56 (10) 1073 - 1710 1345-9678 2015/10 [Refereed]
     
    The adhesive strengths between sol-gel fabricated hydroxyapatite (HAp) films and Ti-29Nb-13Ta-4.6Zr alloy (TNTZ) were evaluated before and after immersion in Ringer's solution at 310K for 7 d. The effect of the surface morphology of TNTZ on the adhesion of HAp films was also investigated. The fracture surfaces after adhesion tests were observed and fracture areas at the interface between HAp films and TNTZ were also evaluated before and after immersion in Ringer's solution. No significant differences in the adhesive strengths between HAp films and TNTZ disks with mirror-polished and mechanically polished surfaces were found. The fracture area at the interface between HAp film and mirror-polished TNTZ disk increases after immersion in Ringer's solution, whereas no fracture occurs at the interface between HAp film and mechanically polished TNTZ disk before and after immersion in Ringer's solution. It is supposed that Ringer's solution penetrates along the cracks that are formed in the HAp films during calcination and the regions with weak adhesion between HAp and TNTZ are connected during immersion in Ringer's solution in the case of HAp films fabricated on mirror-polished TNTZ. From these results, it is found that a relatively rougher surface is effective in improving the adhesion of HAp films fabricated on TNTZ before and after immersion in Ringer's solution.
  • Ken Cho; Mitsuo Niinomi; Masaaki Nakai; Pedro Fernandes Santos; Alethea Morgane Liens; Masahiko Ikeda; Tomokazu Hattori
    Biomaterials Science: Processing, Properties and Applications V: Ceramic Transactions, Volume 254 wiley 254 1 - 12 2015/09 [Refereed]
     
    To evaluate the long-term mechanical biocompatibility of Ti-Mn alloys, the microstructures, Young's moduli, and tensile and fatigue properties of the solutionized Ti-8Mn and Ti-13Mn were investigated. In addition, to evaluate the long-term biological biocompatibility of Ti-Mn alloys, the bone formability of the solutionized Ti-12Mn implant was evaluated by animal testing. The solutionized Ti-8Mn and Ti-13Mn consist of equiaxed P-grains with diameters of approximately 420 m and 430 pm, respectively. Moreover, the solutionized Ti-8Mn also contains an athermal < a phase. The 0.2 % proof stress (σ0.2), tensile strength (σb), and elongation of the solutionized Ti-8Mn are 1148 MPa, 1184 MPa, and 2%, respectively. The σ0.2 and σb decrease to 915 MPa and 953 MPa, respectively, and the elongation increases to 7% for the solutionized Ti-13Mn. The higher strength and significantly lower elongation of the solutionized Ti-8Mn are attributed to precipitation of an athermal ω phase. The fatigue strength of the solutionized Ti-8Mn is comparable to that of the aged Ti-6Al-4V ELI in the low-cycle fatigue life region. The striation widths of the solutionized Ti-8Mn and Ti-13Mn are 2.4 m and 7.8 m, respectively. The smaller striation width of the solutionized Ti-8Mn indicates that the crack propagation rate in the solutionized Ti-8Mn is smaller than that in the solutionized Ti-13Mn. The relative bone contact ratio of the solutionized Ti-12Mn increases from 11% to 29% when the implant period increases from 12 to 52 weeks. The relative bone contact ratios of the solutionized Ti-12Mn implant and the commercially pure Ti implant are almost identical for all implantation periods.
  • Huihong Liu; Mitsuo Niinomi; Masaaki Nakai; Ken Cho
    ACTA BIOMATERIALIA ELSEVIER SCI LTD 24 361 - 369 1742-7061 2015/09 [Refereed]
     
    Along with a high strength, ductility, and work hardening rate, a variable Young's modulus is crucial for materials used as implant rods in spinal fixation surgery. The potential in this context of Ti-(9, 8, 7)Cr-0.2O (mass%) alloys is reported herein. The microstructural and mechanical properties of the alloys were systematically examined as a function of their chromium content, and the ion release of the optimized alloy was investigated to assess its suitability as an implant material. In terms of the deformation-induced omega-phase transformation required for a variable Young's modulus, the balance between beta-phase stability and athermal omega-phase content is most favorable in the Ti-9Cr-0.2O alloy. In addition, this composition affords a high tensile strength (>1000 MPa), elongation at break (similar to 20%), and work hardening rate to solution-treated (ST) samples. These excellent properties are attributed to the combined effects of deformation-induced omega-phase transformation, deformation twinning, and dislocation gliding. Furthermore, the ST Ti-9Cr-0.2O alloy proves resistant to metal ion release in simulated body fluid. This combination of a good biocompatibility, variable Young's modulus and a high strength, ductility, and work hardening rate is ideal for spinal fixation applications. Statement of significance Extensive efforts have been devoted over the past decades to developing beta-type titanium alloys with low Young's moduli for biomedical applications. In spinal fixation surgery however, along with excellent mechanical properties, the spinal-support materials should possess high Young's modulus for showing small springback during surgery to facilitate manipulation but low Young's modulus close to bone once implanted to avoid stress shielding. None of currently used metallic biomaterials can satisfy these above-mentioned requirements. In the present study, we have developed a novel alloy, Ti-9Cr-0.2O. Remarkably variable Young's modulus and excellent mechanical properties can be achieved in this alloy via phase transformations and complex deformation mechanisms, which makes the Ti-9Cr-0.2O preferred material for spinal fixation surgery. (C) 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
  • Kengo Narita; Mitsuo Niinomi; Masaaki Nakai; Suyalatu
    MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING ELSEVIER SCIENCE SA 643 109 - 118 0921-5093 2015/09 [Refereed]
     
    This study investigates the effect of heterogeneous precipitation induced by the segregation of substitutional and interstitial elements in Ti-29Nb-13Ta-4.6Zr alloy (TNTZ) on its mechanical properties. For this, samples both with and without segregation of substitutional elements were prepared, with only the latter being subjected to long-term homogenization. It was found that micro-scale segregation of substitutional elements such as Nb, Ta, and Zr does not significantly affect mechanical properties such as fatigue strength, not even if heterogeneous precipitation occurs as a result of this segregation. On the other hand, segregation of interstitial elements was achieved by controlling the aging time. The segregation of interstitial elements creates precipitate-free zones (PFZs), grain boundary (GB) plates, and Widmanstatten alpha phases with migrating O atoms that all significantly affect the mechanical properties. Specifically, the PFZs have the potential to improve fatigue life, while the Widmanstatten alpha phase increases the tensile strength and reduces the fatigue ratio, the GB-plates reduce elongation, These results indicate that the formation of a Widmanstatten alpha phase by the migration of interstitial elements has a varying influence on the tensile and fatigue properties. 0 2015 Elsevier B.V. All rights reserved.
  • Junko Hieda; Mitsuo Niinomi; Masaaki Nakai; Ken Cho
    MATERIALS SCIENCE & ENGINEERING C-MATERIALS FOR BIOLOGICAL APPLICATIONS ELSEVIER SCIENCE BV 54 1 - 7 0928-4931 2015/09 [Refereed]
     
    Ti-xMg (x = 17, 33, and 55 mass%) alloy films, which cannot be prepared by conventional melting processes owing to the absence of a solid-solution phase in the phase diagram, were prepared by direct current magnetron sputtering in order to investigate their biocompatibility. Ti and Mg films were also prepared by the same process for comparison. The crystal structures were examined by X-ray diffraction (XRD) analysis and the surfaces were analyzed by X-ray photoelectron spectroscopy. The Ti, Ti-xMg alloy, and Mg films were immersed in a 0.9% NaCl solution at 310 K for 7 d to evaluate the dissolution amounts of Ti and Mg. In addition, to evaluate the formation ability of calcium phosphate in vitro, the Ti, Ti-xMg alloy, and Mg films were immersed in Hanks' solution at 310 K for 30 d. Ti and Mg form solid-solution alloys because the peaks attributed to pure Ti and Mg do not appear in the XRD patterns of any of the Ti-xMg alloy films. The surfaces of the Ti-17Mg alloy and Ti-33Mg alloy films contain Ti oxides and MgO, whereas MgO is the main component of the surface oxide of the Ti-55Mg alloy and Mg films. The dissolution amounts of Ti from all films are below or near the detection limit of inductively coupled plasma-optical emission spectroscopy. On the other hand, the Ti-17Mg alloy, Ti-33Mg alloy, Ti-55Mg alloy, and Mg films exhibit Mg dissolution amounts of approximately 2.5, 1.4, 21, and 41 mu g/cm(2), respectively. The diffraction peaks attributed to calcium phosphate are present in the XRD patterns of the Ti-33Mg alloy, Ti-55Mg alloy, and Mg films after the inimersion in Hanks' solution. Spherical calcium phosphate particles precipitate on the surface of the Ti-33Mg film. However, many cracks are observed in the Ti-55Mg film, and delamination of the film occurs after the immersion in Flanks' solution. The Mg film is dissolved in Flanks' solution and calcium phosphate particles precipitate on the glass substrate. Consequently, it is revealed that the Ti-33Mg alloy film evaluated in this study is suitable for biomedical applications. (C) 2015 Elsevier B.V. All tights reserved.
  • High bone bonding ability and affinity of new low-rigidity β-type Ti-29Nb-13Ta-4.6Zr alloy as a dental implant
    H. Edamatsu; T. Kawai; K. Matsui; M. Nakai; T. Takahashi; S. Echigo; M. Niinomi; S. Kamakura
    J. Dent. Oral Health 1 (2) Article ID 009  2015/07 [Refereed]
  • Xiu Song; Lei Wang; Mitsuo Niinomi; Masaaki Nakai; Yang Liu
    MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING ELSEVIER SCIENCE SA 640 154 - 164 0921-5093 2015/07 [Refereed]
     
    A beta-type Ti-29Nb-13Ta-4.6Zr (TNTZ) alloy containing various amounts of TiB reinforcements has been developed to achieve higher fatigue strength for biomedical applications. Fatigue tests were performed at room temperature, and the effects of TiB on fatigue crack initiation and propagation were investigated. The results indicate that the fatigue limit of the TNTZ alloy was substantially improved by the TiB reinforcements. However, the fatigue strength first increased and subsequently decreased as the B concentration increased. TNTZ alloy with 0.10% B has the largest fatigue limit, which is 67% greater than that of the TNTZ alloy. The effects of TiB on the improvement of the fatigue properties are due to the following two factors. First, sliding of the dislocations can be blocked by TiB particles, which results in resistance to fatigue crack initiation. In addition, the crack deflection and crack bridging by the TiB particles could delay the crack propagation. Conversely, debonding of some larger TiB particles may occur, especially when the B concentration is higher than 0.20%. Therefore, the crack initiates from the debonding of the TiB particles and easily propagates along the voids from the interfacial decohesion, which could exert a deleterious influence on the fatigue strength. (C) 2015 Elsevier B.V. All rights reserved.
  • M. Nakai; M. Niinomi; H. Tsutsumi; K. Saito; T. Goto
    MATERIALS TECHNOLOGY TAYLOR & FRANCIS LTD 30 (B1) B8 - B12 1066-7857 2015/02 
    Metal-organic chemical vapour deposition was used to fabricate hydroxyapatite (HAp) and alpha-tricalcium phosphate coatings on the surface of representative biomedical titanium alloys: Ti-29Nb-13Ta-4.6Zr, commercially pure Ti, and Ti-6Al-4V ELI. The effect of the substrate surface roughness, alloy composition and precursor temperature was investigated in relation to the type of calcium phosphate formed and the morphology and thickness of the HAp coating. The surface roughness of substrates mechanically polished by SiC paper was found to vary depending on the type of alloy, whereas the roughness of substrates buff polished using a colloidal SiO2 suspension was comparable. The type of calcium phosphate formed could be controlled by the precursor temperature. A coarse, granular microstructure was observed on the surface of the thicker HAp coatings formed on the rough polished substrates, while the thinner HAp coatings formed on the smooth polished substrates had a relatively dense and fine grained microstructure.
  • H.H. Liu; M. Niinomi; M. Nakai; K. Cho; K. Narita; M. Sen; H. Shiku; T. Matsue
    Acta Biomater. 12 352 - 361 1742-7061 2015/01 [Refereed]
  • Gunawarman; Y. Yetri; Emriadi; N. Jamarun; K. Cho; M. Nakai; M. Niinomi
    Appl. Mech. Mater. 776 193 - 200 2015 [Refereed]
  • Mitsuo Niinomi; Masaaki Nakai; Junko Hieda; Ken-Cho; Yonghwan Kim; Hisao Fukui
    Ceramic Transactions JOHN WILEY & SONS INC 254 63 - 71 1042-1122 2015 [Refereed]
     
    Ag-Pd-Au-Zn alloys are frequently strengthened by an aging treatment after an initial solution treatment. However, Ag-Pd-Au-Zn alloys can be significantly strengthened by solution treatment alone. This phenomenon is unique, as the strength of metallic materials is generally decreased by solution treatment because of the precipitates dissolving into the surrounding matrix. Among the Ag-Pd-Au-Zn alloys, Ag-20Pd-12Au-14.5Cu alloy (in mass %) is the standard compositional alloy used for practical applications. The main source of the solution-treated Ag-20Pd-12Au-14.5Cu alloy strengthening was expected to be a beta' phase formation during the cooling process from the solution treatment's high temperature; this is clarified by changing the solution heat treatment and aging treatment conditions of using as-received wrought Ag-20Pd-12Au-14.5Cu alloy and liquid rapid solidified Ag-20Pd-12Au-14.5Cu alloy.
  • Taekyung Lee; Masaaki Nakai; Mitsuo Niinomi; Chan Hee Park; Chong Soo Lee
    METALS AND MATERIALS INTERNATIONAL KOREAN INST METALS MATERIALS 21 (1) 202 - 207 1598-9623 2015/01 [Refereed]
     
    Ti-29Nb-13Ta-4.6Zr (TNTZ) alloy has been extensively studied as it is promising for use in biomedical applications. Despite its potential, the effects of warm plastic deformation on the alloy have not yet been revealed. This study investigated the differences in phase constitution of two warm-deformed TNTZ alloys and revealed relevant mechanisms with particular attention to martensitic transformation. The influence of phase constituents on mechanical characteristics was discussed as well. The TNTZ alloy deformed at 823 K possessed alpha, beta, and omega phases as well as alpha '' martensite, and demonstrated a low Young's modulus and double-yielding phenomenon. In contrast, the alloy deformed at 723 K had no martensite but more omega phase, leading to increased strength, hardness, and Young's modulus. The absence of alpha '' martensite in the alloy deformed at 723 K was interpreted in light of beta-stability of the parent phase and reduced M-s temperature.
  • Yoon-Seok Lee; Mitsuo Niinomi; Masaaki Nakai; Kengo Narita; Ken Cho
    JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS ELSEVIER SCIENCE BV 41 208 - 220 1751-6161 2015/01 [Refereed]
     
    The predominant factor determining the wear properties of a new titanium alloy, Ti-29Nb-13Ta-4.6Zr (TNTZ) and a conventional titanium alloy, Ti-6Al-4V extra-low interstitial (Ti64) was investigated for TNTZ and Ti64 combinations in metal-to-metal contacting bioimplant applications. The worn surfaces, wear debris, and subsurface damages were analyzed using a scanning electron microscopy combined with energy-dispersive spectroscopy and electron-back scattered diffraction analysis. The volume loss of TNTZ is found to be larger than that of Ti64, regardless of the mating material. The wear track of TNTZ exhibits the galled regions and severe plastic deformation with large flake-like debris, indicative of delamination wear, which strongly suggests the occurrence of adhesive wear. Whereas, the wear track of Ti64 have a large number of regular grooves and microcuttings with cutting chip-like wear debris and microfragmentation of fine oxide debris, indicative of abrasive wear combined with oxidative wear. This difference in the wear type is caused by severe and mild subsurface deformations of TNTZ and Ti64, respectively. The lower resistance to plastic shearing for TNTZ compared to that of Ti64 induces delamination, resulting in a higher wear rate. (C) 2014 Elsevier Ltd. All rights reserved.
  • Yoon-Seok Lee; Mitsuo Niinomi; Masaaki Nakai; Kengo Narita; Ken Cho
    MATERIALS TRANSACTIONS JAPAN INST METALS 56 (3) 317 - 326 1345-9678 2015 [Refereed]
     
    The wear behaviors of combinations comprised of a new titanium alloy, Ti-29Nb-13Ta-4.6Zr (TNTZ) and a conventional titanium alloy, Ti-6Al-4Vextra-low interstitial (Ti64) were investigated using ball-on-disc type configuration in Ringer's solution for metal-to-metal contacting biomedical implant applications. The worn surfaces, wear debris, and subsurface damage were analyzed using a scanning electron microscopy combined with energy-dispersive spectroscopy and an electron probe microanalysis. Moreover theses wear characteristics are compared to the results obtained from the wear tests in air. Volume loss of both the disc and ball primarily increases for the TNTZ disc/TNTZ ball combination in Ringer's solution compared to that in air. This increase can be explained by the ejection of debris from the contact region induced by the presence of Ringer's solution. Subsequently, this increases the number of areas with asperity junctions between the disc and ball, thereby leading to severe delamination wear. In contrast, the volume loss of both the disc and ball decrease for the Ti64 disc/Ti64 ball combination in Ringer's solution compared to that in air. It is believed that the predominately abrasive wear associated with Ti64 is effectively suppressed by the use of Ringer's solution.
  • Xiu Song; Lei Wang; Mitsuo Niinomi; Masaaki Nakai; Yang Liu; Miaoyong Zhu
    MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING ELSEVIER SCIENCE SA 619 112 - 118 0921-5093 2014/12 [Refereed]
     
    The new p-type Ti-29Nb-13Ta-4.6Zr (TNTZ) alloy containing trace amounts of CeO2 additions has been designed as a biomedical implant with improved fatigue properties achieved by keeping Young's modulus to a low value. The results show that the microstructure is refined by the addition of CeO2; the p grain size becomes a little larger when Ce content increases from 0.05% to 0.10%. This occurs because dispersed CeO2 particles can act as nucleation sites for p grains; thus, the effect of rare earth oxides on microstructure refinement mainly depends on the size and dispersion of the rare earth oxides. Young's moduli of TNTZ with CeO(2)additions are maintained as low as those of TNTZ without CeO2, while the fatigue limit is highly improved. The 0.10% Ce alloy exhibits the best fatigue strength among the experimental alloys; its fatigue strength is increased by 66.7% compared to that of pure TNTZ. The mechanism by which rare earth oxides affect fatigue performance is dominated by dispersion strengthening. The stiff rare earth oxides can hinder the movement of dislocations, resulting in resistance to the formation of fatigue cracks. Rare earth oxides also change the crack propagation direction and the crack propagation route, effectively decreasing the crack propagation rate. (C) 2014 Elsevier B.V. All rights reserved.
  • H. Yilmazer; M. Niinomi; K. Cho; M. Nakai; J. Hieda; S. Sato; Y. Todaka
    ACTA MATERIALIA PERGAMON-ELSEVIER SCIENCE LTD 80 172 - 182 1359-6454 2014/11 
    In order to elucidate the microstructural refinement mechanism and the effect of secondary phase on the microstructural evolution of beta-type titanium alloy, severe plastic deformation was conducted on samples of a precipitation-hardened Ti-29Nb-13Ta-4.6Zr (TNTZ). Specifically, TNTZ that was precipitation-hardened through an aging treatment (TNTZAT) was subjected to high-pressure torsion (HPT) processing (TNTZ(AHPT)). The microstructure of TNTZ(AHPT), which has been evaluated as a function of the torsional rotation number, N, exhibits ultrafine elongated beta grains. The needle-like alpha precipitates in TNTZ(AT), which exhibit a diameter of approximately 12 nm, are homogeneously distributed within the beta grains. The dislocation density and subgrain diameter, estimated by X-ray line profile analysis, saturate at approximately 4.2 x 10(16) m(-2) and 12.2 nm, respectively, at N >= 10. The beta grains contain nanostructured subgrains having non-uniform morphologies surrounded by blurred and wavy boundaries. A saturated hardness distribution at approximately 450 HV indicates that microstructural homogeneity has been achieved at N >= 10. The alpha precipitates enhance the beta grain refinement and microstructural homogeneity is achieved in TNTZ(AHPT) at N >= 10, whereas this occurs at later stages (N > 20) in TNTZ which is solution-treated and therefore does not contain any alpha precipitates. (C) 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
  • Yonghwan Kim; Mitsuo Niinomi; Junko Hieda; Masaaki Nakai; Ken Cho; Hisao Fukui
    JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS ELSEVIER SCIENCE BV 35 123 - 131 1751-6161 2014/07 
    Ag-Pd-Au-Cu alloys have been used widely for dental prosthetic applications. Significant enhancement of the mechanical properties of the Ag-20Pd-12Au-14.5Cu alloy as a result of the precipitation of the beta' phase through high-temperature solution treatment (ST), which is different from conventional aging treatment in these alloys, has been reported. The relationship between the unique hardening behavior and precipitation of the beta' phase in Ag-20Pd-12Au-xCu alloys (x=6.5, 13, 14.5, 17, and 20 mass%) subjected to the high-temperature ST at 1123 K for 3.6 ks was investigated in this study. Unique hardening behavior after the high-temperature ST also occurs in Ag-20Pd-12Au-xCu alloys (x=13, 17, and 20) with precipitation of the beta' phase. However, hardening is not observed and the beta' phase does not precipitate in the Ag-20Pd-12Au-6.5Cu alloy after the same ST. The tensile strength and 0.2% proof stress also increase in Ag-20Pd-12Au-xCu alloys (x=13, 14.5, 17, and 20) after the high-temperature ST. In addition, these values after the high-temperature ST increase with increasing Cu content in Ag-20Pd-12Au-xCu alloys (x=14.5, 17, and 20). The formation process of the beta' phase can be explained in terms of diffusion of Ag and Cu atoms and precipitation of the beta' phase. Clarification of the relationship between hardening and precipitation of the beta' phase via high-temperature ST is expected to help the development of more effective heat treatments for hardening in Ag-20Pd-12Au-xCu alloys. (C) 2014 Elsevier Ltd. All rights reserved.
  • Huihong Liu; Mitsuo Niinomi; Masaaki Nakai; Junko Hieda; Ken Cho
    SCRIPTA MATERIALIA PERGAMON-ELSEVIER SCIENCE LTD 82 29 - 32 1359-6462 2014/07 [Refereed]
     
    Materials used for implant rods in spinal fixation systems must show changeable Young's moduli, high strength and large elongation-to-failure. A d-electron design method was used to determine the chemical composition of Ti-10Cr, which showed all these properties and significant work-hardening characteristics owing to multiple plastic deformation mechanisms, such as deformationinduced omega-phase transformation, {3 3 2}<1 1 3> mechanical twinning and dislocation gliding. Therefore, Ti-10Cr exhibits great potential for use in spinal fixation applications. (c) 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
  • Huihong Liu; Mitsuo Niinomi; Masaaki Nakai; Junko Hieda; Ken Cho
    JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS ELSEVIER SCIENCE BV 34 66 - 74 1751-6161 2014/06 [Refereed]
     
    The springback behavior of Ti-12Cr and Ti-29Nb-13Ta-4.6Zr (TNTZ) during deformation by bending was investigated; and the microstructures of the non-deformed and deformed parts of both alloys were systematically examined to clarify the relationship between microstructure and springback behavior. For the deformed Ti-12Cr alloy, deformation-induced omega-phase transformation occurs in both the areas of compression and tension within the deformed part, which increases the Young's modulus. With the deformed TNTZ alloy, deformation-induced omega-phase transformation is observed in the area of compression within the deformed part; while a deformation-induced alpha '' martensite transformation occurs in the area under tension, which is likely to be associated with the pseudoelasticity of TNTZ. Among these two alloys, Ti-12Cr exhibits a smaller springback and a much greater bending strength when compared with TNTZ; making Ti-12Cr the more advantageous for spinal fixation applications. (C) 2014 Elsevier Ltd. All rights reserved.
  • Yonghwan Kim; Mitsuo Niinomi; Junko Hieda; Masaaki Nakai; Ken Cho; Hisao Fukui
    MATERIALS SCIENCE & ENGINEERING C-MATERIALS FOR BIOLOGICAL APPLICATIONS ELSEVIER SCIENCE BV 37 204 - 209 0928-4931 2014/04 
    Dental Ag-20Pd-12Au-14.5Cu alloys exhibit a unique hardening behavior, which the mechanical strengths enhance significantly which enhances the mechanical strength significantly after high-temperature (1123 K) solution treatment without aging treatment. The mechanism of the unique hardening is not clear. The contribution of two precipitates (beta' and beta phases) to the unique hardening behavior in the as-solutionized Ag-20Pd-12Au-14.5Cu alloys was investigated. In addition, the chemical composition of the beta' phase was investigated. The fine beta' phase densely precipitates in a matrix. The beta' phase (semi-coherent precipitate), which causes lattice strain, contributes greatly to the unique hardening behavior. On the other hand, the coarse beta phase sparsely precipitates in the matrix. The contribution of the beta phase (incoherent precipitate), which does not cause lattice strain, is small. The chemical composition of the beta' phase was determined. This study reveals that the fine beta' phase precipitated by high-temperature solution treatment leads to the unique hardening behavior in dental Ag-20Pd-12Au-14.5Cu alloys in the viewpoints of the lattice strain contrast and interface coherency. It is expected to make the heat treatment process more practical for hardening. The determined chemical composition of beta' phase would be helpful to study an unknown formation process of beta' phase. (C) 2014 Elsevier B.V. All rights reserved.
  • Junko Hieda; Mitsuo Niinomi; Masaaki Nakai; Ken Cho; Tomoyoshi Mohri; Takao Hanawa
    MATERIALS SCIENCE & ENGINEERING C-MATERIALS FOR BIOLOGICAL APPLICATIONS ELSEVIER SCIENCE BV 36 244 - 251 0928-4931 2014/03 [Refereed]
     
    Anodic oxide nanostructures (nanopores and nanotubes) were fabricated on a biomedical beta-type titanium alloy, Ti-29Nb-13Ta-4.6Zr alloy (TNTZ), by anodization in order to improve the adhesive strength of a medical polymer, segmented polyurethane (SPU), to TNTZ. TNTZ was anodized in 1.0 M H3PO4 solution with 0.5 mass% NaF using a direct-current power supply at a voltage of 20 V. A nanoporous structure is formed on TNTZ in the first stage of anodization, and the formation of a nanotube structure occurs subsequently beneath the nanoporous structure. The nanostructures formed on TNTZ by anodization for less than 3600 s exhibit higher adhesive strengths than those formed at longer anodization times. The adhesive strength of the SPU coating on the nanoporous structure formed on top of TNTZ by anodization for 1200 s improves by 144% compared to that of the SPU coating on as-polished TNTZ with a mirror surface. The adhesive strength of the SPU coating on the nanotube structure formed on TNTZ by anodization for 3600 s increases by 50%. These improvements in the adhesive strength of SPU are the result of an anchor effect introduced by the nanostructures formed by anodization. Fracture occurs at the interface of the nanoporous structure and the SPU coating layer. In contrast, in the case that SPU coating has been performed on the nanotube structure, fracture occurs inside the nanotubes. (C) 2013 Elsevier B.V. All rights reserved.
  • Yonghwan Kim; Mitsuo Niinomi; Junko Hieda; Masaaki Nakai; Ken Cho; Hisao Fukui
    MATERIALS SCIENCE & ENGINEERING C-MATERIALS FOR BIOLOGICAL APPLICATIONS ELSEVIER SCIENCE BV 36 329 - 335 0928-4931 2014/03 
    The age-hardening behavior of the dental-casting Ag-20Pd-12Au-14.5Cu alloy subjected to aging treatment at around 673 K is well known, and this hardening has been widely employed in various applications. To date, the age-hardening of this alloy has been explained to attribute to the precipitation of a beta phase, which is a B2-type ordered CuPd phase or PdCuxZn1-x phase. In this study, results obtained from microstructural observations using a transmission electron microscopy and a scanning transmission electron microscopy revealed that a fine L1(0)-type ordered beta' phase precipitated in the matrix and a coarse-structure region (consisting of Ag- and Cu-rich regions) appeared after aging treatment at 673 K and contributed to increase in hardness. The microstructure of the coarse beta phase, which existed before aging treatment, did not change by aging treatment. Thus, it is concluded that the fine beta' phase precipitated by aging treatment contributed more to increase in hardness than the coarse-structure region and coarse beta phase. (C) 2013 Elsevier B.V. All rights reserved.
  • Huihong Liu; Mitsuo Niinomi; Masaaki Nakai; Junko Hieda; Ken Cho
    JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS ELSEVIER SCIENCE BV 30 205 - 213 1751-6161 2014/02 [Refereed]
     
    In order to meet the requirements of the patients and surgeons simultaneously for spinal fixation applications, a novel biomedical alloy with a changeable Young's modulus, that is, with a low Young's modulus to prevent the stress-shielding effect for patients and a high Young's modulus to suppress springback for surgeons, was developed. In this study, the chromium and oxygen contents in ternary Ti(11, 12 mass%)Cr-(0.2, 0.4, 0.6 mass%)0 alloys were optimized in order to achieve a changeable Young's modulus via deformation-induced omega-phase transformation with good mechanical properties. The Young's moduli of all the examined alloys increase after cold rolling, which is attributed to the deformation-induced (omega-phase transformation. This transformation is suppressed by oxygen but enhanced with lower chromium content, which is related to the beta(bcc)-lattice stability. Among the examined alloys, the Ti-11Cr-0.2O alloy shows a low Young's modulus of less than 80 GPa in the solution-treated (ST) condition and a high Young's modulus of more than 90 GPa in the cold rolled (CR) condition. The Ti-11Cr-0.2O alloy also exhibits a high tensile strength, above 1000 MPa, with an acceptable elongation of similar to 12% in the ST condition. Furthermore, the Ti-11Cr-0.2O alloy exhibits minimal springback. This value of springback is the closest to that of Ti64 ELI alloy among the compared alloys. Therefore, the Ti-11Cr-0.2O alloy, which has a good balance between large changeable Young's modulus, high tensile strength, good plasticity, and minimal springback, is considered to be a potential candidate for spinal fixation applications. (C) 2013 Elsevier Ltd. All rights reserved.
  • Development of low-cost high-strength beta-type titanium alloys using a metal injection molding
    K. Cho; M. Niinomi; M. Nakai; J. Hieda; P.F. Santos; Y. Itoh; M. Ikeda
    Proceedings of Materials Science and Technology Conference and Exhibition 2014 (MS&T2014) 1551 - 1558 2014
  • Optimization of Cr and O contents in beta-type Ti-Cr-O alloys for obtaining both larger changeable Young's modulus during deformation and higher strength for use in spinal fixation applications
    M. Nakai; M. Niinomi; J. Hieda; K. Cho; K. Narita; H.H. Liu
    Proceedings of Materials Science and Technology Conference and Exhibition 2013 (MS&T2013) 2991 - 2997 2014
  • Mitsuo Niinomi; Masaaki Nakai; Junko Hieda; Ken Cho; Kengo Narita
    TMS 2014 SUPPLEMENTAL PROCEEDINGS JOHN WILEY & SONS INC 205 - 212 2014 
    Newly developed low-modulus beta-type titanium alloys such as Ti-29Nb-13Ta-4.6Zr (TNTZ) and Ti-Cr alloys are expected to be used for rods in spinal fixation devices. As the endurance, i.e., fatigue strength, is one of the most important factors for this application. Various types of fatigue strengths of TNTZ and Ti-Cr alloys as well as their developments were investigated. Compared to conventional Ti-6Al-4V extra low interstitials (ELI) for biomedical applications the uni-axial fatigue strength of TNTZ is increased significantly by thermomechanical processing, which includes solution treatment, severe cold swaging or rolling, and followed by aging treatment. The uni-axial fatigue strength of Ti-12Cr is significantly higher compared to that of Ti-6Al-4V ELI. The four point bending fatigue strengths of the alloys exhibit opposite trends.
  • Mitsuo Niinomi; Masaaki Nakai; Junko Hieda; Ken Cho; Yoshio Itsumi; Shogo Murakami; Hideto Oyama; Wataru Abe
    TMS 2014 SUPPLEMENTAL PROCEEDINGS JOHN WILEY & SONS INC 49 - 56 2014 
    Ti-4.5Al-2.5Cr-1.2Fe-0.1C referred to as KS Ti-531C is a newly developed low cost titanium alloy for use in next-generation aircrafts by adding inexpensive elements such as C, Fe, Al and Cr. There is a possibility for the formation of TiCr and/or TiCr2 after a long heat treatment or welding. Therefore, relationships between the microstructures and fatigue properties of KS Ti-531C subjected to several heat treatments as well as laser welding were investigated systematically. The results showed that the fatigue strength of laser-welded KS Ti-531C was lower than that of non-laser welded KS Ti-531C.
  • Masaaki Nakai; Mitsuo Niinomi; Junko Hieda; Ken Cho; Yoon-Seok Lee
    TMS 2014 SUPPLEMENTAL PROCEEDINGS JOHN WILEY & SONS INC 217 - 220 2014 
    A biomedical beta-type titanium, Ti-29Nb-13Ta-4.6Zr alloy (TNTZ), exhibits good biological and mechanical biocompatibilities due to containing non-toxic elements and lower Young's modulus than that of a conventional (alpha+beta)-type titanium alloy, Ti-6Al-4V ELI alloy (Ti64). One of the expected applications for TNTZ is spinal fixation applications. However, screws and rods are contacted each other in this kind of application, while titanium alloys generally exhibit poor wear resistance. Therefore, the wear characteristics of TNTZ and Ti64 were investigated in this study. Balls and discs made of TNTZ and Ti64 were prepared for a ball-on-disc wear test. As the results of microstructural analysis, it was found that the morphologies of wear tracks and debris of TNTZ are different from those of Ti64 because different wear mechanism is predominant in each alloy.
  • K. Cho; M. Niinomi; M. Nakai; J. Hieda; P.F. Santos; Y. Itoh; T. Hattori; M. Ikeda
    Mater. Sci. Forum 783-786 1232 - 1237 0255-5476 2014 
    Mechanical biocompatibility, including tensile properties and Young's modulus, of β-type Ti-Mn alloys, namely, Ti-10Mn and Ti-14Mn, fabricated by the metal injection molding method were investigated. The bone formability (biological biocompatibility) of a Ti-Mn alloy, namely, Ti-12Mn, fabricated by the arc-melting method was evaluated by means of an animal test. The tensile strength of sintered Ti-10Mn and Ti-14Mn achieve a maximum value of 860 and 886 MPa, respectively. The Ti-14Mn specimen sintered at 1273 K shows the lowest Young's modulus (76 GPa) among all sintered Ti-10Mn and Ti-14Mn specimens. The tensile strength of Ti-Mn alloys is almost equal to that of Ti64 ELI; further, their Young's modulus is lower than that of Ti-6Al-4V ELI. The relative bone contact ratio of Ti-12Mn increases from 11% to 29% with increasing implantation time from 12 weeks to 52 weeks. Moreover, the relative bone contact ratio of Ti-12Mn and CP-Ti is almost constant for all implantation times. © (2014) Trans Tech Publications, Switzerland.
  • Mitsuo Niinomi; Masaaki Nakai; Junko Hieda; Ken Cho; Toshihiro Kasuga; Tomokazu Hattori; Takashi Goto; Takao Hanawa
    INTERNATIONAL JOURNAL OF SURFACE SCIENCE AND ENGINEERING INDERSCIENCE ENTERPRISES LTD 8 (2-3) 138 - 152 1749-785X 2014 
    Ti-29Nb-13Ta-4.6Zr (TNTZ) is a novel beta-type titanium alloy that has great potential use in biomedical implants because of its relatively low Young's modulus (around 60 GPa), which minimise bone atrophy due to stress shielding. However, the biocompatibility and bio-functionality of TNTZ is poor. Therefore, a bioactive ceramic surface modification or soft-tissue-compatible polymer surface modification is advantageous for enhancing the biological properties of TNTZ. The bio-functionality of TNTZ itself, and that modified with a coating hydroxyapatite (HAp) using alkali treatment, electrochemical treatment, and dip-coating treatment with calcium phosphate glass ceramic or metal organic chemical vapour deposition (MOCVD) is assessed. In addition, modification of TNTZ with soft-tissue-compatible segmented polyurethane (SPU) using different silane coupling agents is described. The bonding strength of the bioactive ceramic and soft-tissue compatible polymer with the TNTZ is assessed with respect to variations in surface roughness.
  • Biomedical implant devices fabricated from low Young's modulus titanium alloys with demonstrating high mechanical biocompatibility
    M. Niinomi; M. Nakai
    Mater. Matters 9 39 - 46 2014
  • Huihong Liu; Mitsuo Niinomi; Masaaki Nakai; Junko Hieda; Ken Cho
    RECENT HIGHLIGHTS IN ADVANCED MATERIALS TRANS TECH PUBLICATIONS LTD 575-576 453 - 460 1013-9826 2014 [Refereed]
     
    A novel beta-type titanium alloy with a changeable Young's modulus, that is, with a low Young's modulus to prevent the stress-shielding effect for patients and a high Young's modulus to suppress springback for surgeons, should be developed in order to satisfy the conflicting requirements of both the patients and surgeons in spinal fixation operations. In this study, the oxygen content in ternary Ti-11Cr-O alloys was optimized in order to achieve a large changeable Young's modulus with good mechanical properties for spinal fixation applications. The increase in Young's moduli of all the examined alloys by cold rolling is attributed to the deformation-induced omega-phase transformation which is suppressed by oxygen. Among the examined alloys, the Ti-11Cr-0.2O alloy exhibits the largest changeable Young's modulus and a high tensile strength with an acceptable plasticity under both solution-treated (ST) and cold-rolled (CR) conditions. Therefore, the Ti-11Cr-0.2O alloy, which shows a good balance among a changeable Young's modulus, high tensile strength and good plasticity, is considered a potential candidate for spinal fixation applications.
  • Mitsuo Niinomi; Masaaki Nakai; Junko Hieda; Ken Cho; Kengo Narita
    Key Eng. Mater. TRANS TECH PUBLICATIONS LTD 575-576 446 - 452 1013-9826 2014 [Refereed]
     
    The fatigue strength of the newly developed beta-type titanium alloy Ti-29Nb-13Ta-4.6Zr (referred to as TNTZ) is important for its applications in spinal fixation rods. Enhancements in the fatigue strength of TNTZ upon solution treatmnet and thermo-mechanical processing (aging after severe cold-caliber rolling or sever cold-swaging) have been investigated. Aging the rods at 723 K for 259.2 ks after cold-swaging is shown to be the optimal thermo-mechanical processing method for the TNTZ rod, yeilding a high 0.2% proof stress of about 1200 MPa, high elongation of 18%, and high fatigue strength of 950 MPa. High springback is undesirable for application of TNTZ spinal-fixation rods. To reduce springback, a High Young's modulus is required; on the other hand, a low Young's modulus is beneficial to reduce bone absorption and obtain good bone remodeling. To achieve a balance between these two factors, TNTZ has been modified by adding Cr to obtain an alloy with a high Young's modulus at the deformed region and a low Young's modulus throughout the undeformed region. TNTZ-8Ti-2Cr and TNTZ-16Ti-4Cr are novel alloys whose beta phase is more stable than that of TNTZ. Only the beta phase is present in these alloys, which exhibit relatively low Young's moduli of <65 GPa after solution treatment, and higher Young's moduli after cold rolling, owing to a deformation-induced omega-phase transformation. These modified TNTZ alloys show significantly less springback than the original TNTZ, based on tensile and loading unloading bending tests.
  • Hakan Yimazer; Mitsuo Niinomi; K. Cho; M. Nakai; J. Hieda; Y. Todaka
    11TH INTERNATIONAL FATIGUE CONGRESS, PTS 1 AND 2 TRANS TECH PUBLICATIONS LTD 891-892 9 - 14 1022-6680 2014 
    A novel beta-type, Ti-29Nb-13Ta-4.6Zr, referred to as TNTZ has been developed for biomedical applications. Its fatigue strength is one of the most important mechanical biocompatibilities of TNTZ because, in surgical applications, it will be used under cyclic loading conditions. The effect of the microstructural refinement by high-pressure torsion (HPT) on the fatigue behaviour of TNTZ is systematically investigated in this study. TNTZ subjected to HPT processing where the rotation number (N) is 20 (TNTZ(AHPT)) after aging treatment (AT) shows a unique microstructure having ultrafine elongated grains (285 nm in length and 36 nm in width) with high-density dislocations, a large fraction of blurred and wavy boundaries consisting of non-uniform subgrains with high misorientation and nanostructured precipitated alpha phase. Remarkably, a good combination of high mechanical strength (1375 MPa) and low Young's modulus (87 GPa), compared to that of Ti-6Al-4V (Ti64) ELI, is achieved for TNTZ(AHPT) at N = 20. TNTZ(AHPT) a great fatigue strength, which is comparable to those of (Ti64) ELI.
  • Yoon-Seok Lee; Mitsuo Niinomi; Masaaki Nakai; Kengo Narita; Junko Hieda; Ken Cho
    Key Eng. Mater. TRANS TECH PUBLICATIONS LTD 616 270 - 274 1013-9826 2014 [Refereed]
     
    The wear mechanisms of conventional Ti-6Al-4V extra-low interstitial (Ti64) and the new Ti-29Nb-13Ta-4.6Zr (TNTZ) were studied to investigate the wear properties of Ti64/TNTZ for application in spinal fixation devices. Ti64 and TNTZ balls and discs were first prepared as wear-test specimens. A ball-on-disc frictional wear-testing machine was used in air to perform the frictional wear tests of the Ti64 and TNTZ discs mated against Ti64 and TNTZ balls. The wear mechanisms were investigated using a scanning electron microscopy to analyze the worn surfaces and wear debris. The volume losses for the TNTZ discs were larger than those for the Ti64 ones, regardless of the mating ball material. Furthermore, the morphologies of the wear tracks and the debris of the Ti64 and TNTZ discs were different, suggesting that the wear mechanisms for the Ti64 and TNTZ discs were abrasive and delamination wear caused by mild and severe subsurface deformations of the Ti64 and TNTZ, respectively, regardless of the mating ball material.
  • Murat Isik; Mitsuo Niinomi; Ken Cho; Masaaki Nakai; Junko Hieda; Hakan Yilmazer; Zenji Horita; Takayuki Narushima
    ADVANCED CERAMICS AND NOVEL PROCESSING TRANS TECH PUBLICATIONS LTD 616 263 - 269 1013-9826 2014 
    The effect of high-pressure torsion (HPT) processing on the microstructure and Vickers hardness of Co-Cr-Mo (CCM) alloys were investigated in this study. The microstructure of initial CCM alloy contains equiaxed grains with a grain diameter of approximately 50 mu m and twins. The clear grain boundaries of equiaxed grains and twins disappear after HPT processing at a rotation number, N, of 10. The phase maps of initial CCM alloy and CCM alloy subjected to HPT processing at N = 5 measured by electron backscatter diffraction exhibit that the ratio of. phase decreases from 93.5% to 34.1% and the ratio of e phase increases from 6.5% to 65.9% by applying HPT processing. These results indicate that the e phase is formed by high-strain, which is induced by the HPT processing. The Vickers hardness values on the surfaces of the CCM alloys subjected to HPT processing at N = 1, 5, and 10 increase with increasing the equivalent strain, epsilon(eq). These results suggest that an increase of Vickers hardness is correlated to an increase of the ratio of epsilon phase and the dislocation density, and grain refinement, which are caused by the high-strain induced by HPT processing.
  • M. Niinomi; M. Nakai; J. Hieda; K. Cho; T. Goto; T. Hanawa
    Mater. Sci. Forum 783-786 78 - 84 2014
  • M. Nakai; M. Niinomi; J. Hieda; K. Cho; K. Narita; X.F. Zhao
    Mater. Sci. Forum 783-786 1307 - 1312 2014
  • K. Narita; M. Niinomi; M. Nakai
    Mater. Sci. Forum 783-786 1313 - 1319 2014
  • Yoon-Seok Lee; Mitsuo Niinomi; Masaaki Nakai; Junko Hieda; Ken Cho
    Advanced Materials Research Trans Tech Publications 922 424 - 428 1022-6680 2014 
    The wear mechanisms of a conventional titanium alloy, Ti-6Al-4V extra-low interstitial (Ti64), and a new titanium alloy, Ti-29Nb-13Ta-4.6Zr alloy (TNTZ) were studied to investigate the wear properties of a Ti64/TNTZ combination for spinal fixation devices. Balls and discs made of Ti64 and TNTZ were prepared to be used as wear-test specimens. Frictional wear tests of Ti64 and TNTZ discs were carried out against Ti64 and TNTZ balls in air using a ball-on-disc frictional wear testing system. The wear mechanisms were investigated by analysis of worn surfaces and wear debris using scanning electron microscopy. Volume losses of the TNTZ discs were found to be larger than those of the Ti64 discs, regardless of mating ball. Furthermore, the morphologies of wear tracks and debris were found to be different between TNTZ and Ti64 discs. It is considered that the wear mechanism for a Ti64 disc is oxidative wear, whereas that for a TNTZ disc is delamination wear, regardless of mating ball material. © (2014) Trans Tech Publications, Switzerland.
  • Hakan Yilmazer; Mitsuo Niinomi; Ken Cho; Masaaki Nakai; Junko Hieda; Shigeo Sato; Yoshikazu Todaka
    Advanced Materials Letters VBRI Press 5 (7) 378 - 383 0976-397X 2014 
    A novel β-type titanium alloy Ti-29Nb-13Ta-4.6Zr (TNTZ) has been developed and extensively researched to achieve highly desirable mechanical properties such as a high strength while maintaining a low Young's modulus that is close to that of bone, as an alternative candidate for conventional titanium metallic biomaterials such as Ti-6Al-4V ELI. Therefore, strengthening by grain refinement and increasing dislocation density is expected to provide TNTZ high mechanical strength while keeping a low Young's modulus because they keep the original β phase. In this case, severe plastic deformation, such as high-pressure torsion (HPT) processing, is a potential treatment for obtaining these properties. Furthermore, HPT processing is effective for producing ultrafine-grained TNTZ having high dislocation density in single β structure. The obtained promising results, which are a tensile strength of around 1100 MPa and a Young's modulus of around 60 GPa, motivated that the above mentioned mechanical properties can be achieved by microstructural refinement through HPT processing However, the mechanism of microstructural refinement is unclear for TNTZ during HPT processing. Therefore, the aim of this study is to investigate microstructural changes of TNTZ through HPT processing by X-ray diffraction analysis and transmission electron microscopy. The microstructures of TNTZ subjected to cold rolling (TNTZCR) and HPT processing (TNTZHPT) comprised single β grains however, the intense β {110} peak reveals that the preferred orientation is β {110} for TNTZHPT. While the microstructure of TNTZCR shows a comparatively high dislocation density (2.3 x 1016 m-2), HPT processing leads to a drastic accumulation of dislocations (5.3 x 1016 m-2 in dislocation density). Dislocations in the microstructures of TNTZHPT are well arranged for the cell wall and/or subgrain boundaries, with a stronger dipole character than random distribution. The dislocation density, arrangement parameter and crystallite diameter (around 11 nm) of TNTZHPT saturate from the center to the peripheral region of a coin shaped specimen at N = 20. Therefore, such a microstructural saturation in a specific strain inducing, N = 20, suggests a threshold for further investigation of β-type titanium alloys. Copyright. © 2014 VBRI press.
  • Kengo Narita; Mitsuo Niinomi; Masaaki Nakai
    Journal of the Mechanical Behavior of Biomedical Materials 29 393 - 402 1751-6161 2014/01 [Refereed]
     
    Some newly developed β-type titanium alloys for biomedical applications exhibit distinctive heterogeneous structures. The formation mechanisms for these structures have not been completely revealed however, understanding these mechanisms could lead to improving their properties. In this study, the heterogeneous structures of a Ti-29Nb-13Ta-4.6Zr alloy (TNTZ), which is a candidate for next-generation metallic biomaterials, were analyzed. Furthermore, the effects of such heterogeneous structures on the mechanical strength of this alloy, including fatigue strength, were revealed by comparing its strength to that of homogenous TNTZ. The heterogeneous structures were characterized micro-, submicro- and nano-scale wave-like structures. The formation mechanisms of these wave-like structures are found to be different from each other even though their morphologies are similar. It is revealed that the micro-, submicro- and nano-scale wave-like structures are caused by elemental segregation, crystal distortion related to kink band and phase separation into β and β', respectively. However, these structures have no significant effect on both tensile properties and fatigue strength comparison with homogeneous structure in this study. © 2013 Elsevier Ltd.
  • Mechanical properties of biomedical β-type titanium alloy with rare-earth oxide particles formed by rare-earth metal addition
    J. Hieda; M. Niinomi; M. Nakai; K. Cho
    TMS2014 Annual Meeting Supplemental Proceedings 129 - 135 2014
  • 仲井正昭; 新家光雄
    バイオマテリアル―生体材料― 日本バイオマテリアル学会 ; 2002- 32 (3) 217 - 228 1347-7080 2014
  • Masaaki Nakai; Mitsuo Niinomi; Junko Hieda; Ken Cho; Yuya Nagasawa; Takashi Konno; Yoshinori Ito; Yoshio Itsumi; Hideto Oyama
    MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING ELSEVIER SCIENCE SA 594 103 - 110 0921-5093 2014/01 [Refereed]
     
    In order to reduce the anisotropy of mechanical properties of a coilable thin sheet of (alpha + beta)-type titanium alloy, Ti-4.5Al-2Mo-1.6V-0.5Fe-0.3Si-0.03C (Ti9), for use in aircraft applications, duplex heat treatments were examined. In each duplex heat treatment, the first heat treatment controls the volume fraction of the primary alpha phase and orientation of the acicular alpha phase in (alpha + beta) two-phase area between the primary alpha grains, whereas the second heat treatment stabilizes the alpha and beta phases. The microstructure of the Ti9 sheet after the duplex heat treatment was analyzed by optical microscopy, pole-figure measurement through X-ray diffraction, and electron backscatter diffraction. The mechanical properties of the duplex heat-treated Ti9 sheet were evaluated by tensile tests. The Ti9 sheet was heat treated to obtain two different types of microstructures. A microstructure consisting of acicular alpha phase in the beta grains was obtained by a first heat treatment above the beta transus (1273 K) followed by water quenching and a second heat treatment at 973 K. A microstructure consisting of equiaxed primary alpha grains and an (acicular alpha + beta) two-phase area between the primary alpha grains was obtained by heating below the beta transus (1123-1223 K) followed by water quenching and a second heat treatment at 973 K. The volume fraction of the primary is grains decreased and the volume fraction of the acicular alpha phase with 12 variants increased instead of increasing first heat-treatment temperature, suppressing the alignment of the c axis of the alpha lattice parallel to the transverse direction within the rolling plane (T-texture formation) as a result. Anisotropy of the tensile properties can be decreased by increasing the first heat-treatment temperature because the T texture was decreased. (C) 2013 Elsevier B.V. All rights reserved.
  • K. Cho; M. Niinomi; M. Nakai; J. Hieda; P.F. Santos; Y. Itoh; M. Ikeda
    Ceram. Trans. JOHN WILEY & SONS INC 251 21 - 30 1042-1122 2014 [Refereed]
     
    Tensile properties, Young's modulus and microstructures of (beta-type Ti-10Mn and Ti-14Mn that were fabricated using a metal injection molding method were investigated as a function of sintering temperature. To investigate the biocompatibility of these Ti-Mn alloys, the metallic ions released in a simulated body fluid from Ti-10Mn and Ti-14Mn that were fabricated using a cold crucible levitation melting method were evaluated by immersion tests. The tensile strengths of the sintered Ti-10Mn and Ti-14Mn achieve maximum values of 860 and 886 MPa, respectively. The Ti-14Mn sintered at 1273 K shows the lowest Young's modulus (76 GPa) among all the sintered Ti-10Mn and Ti-14Mn. The tensile strengths of the Ti-Mn alloys are equal to that of (alpha + beta)-type Ti-6Al-4V ELI (Ti64 ELI); further, their Young's moduli were lower than that of Ti-64 ELI. The Ti ions released in a 1% lactic acid solution from the Ti-10Mn and Ti-14Mn is the same levels as that from pure Ti. The Mn ions released into 1% lactic acid solution from the Ti-10Mn and Ti-14Mn does not show a significant increase with increasing Mn content of the Ti-Mn alloys. The ratio of the amount of the Mn ion released to the amount of the (Ti + Mn) ion released in the 1% lactic acid solution corresponds to the Mn content of the Ti-Mn alloys. These results indicated that the ion-release behaviors of the Ti-Mn alloys in the 1% lactic acid solution are the same as that of pure Ti.
  • Ken Cho; Mitsuo Niinomi; Masaaki Nakai; Junko Hieda; Ryota Kanekiyo
    MATERIALS TRANSACTIONS JAPAN INST METALS 54 (10) 2000 - 2006 1345-9678 2013/10 [Refereed]
     
    To investigate methods of improving the tensile and fatigue properties of a solutionized Ti-29Nb-13Ta-4.6Zr (TNTZ) alloy without increasing its Young' modulus, two types of TNTZ alloys having oxygen contents of 0.06 and 0.14 mass% (TNTZ-0.06O and TNTZ-0.14O), respectively, were subjected to cold swaging and a subsequent heat-treatment. The effects of the grain refinement caused by the cold swaging and the subsequent heat-treatment as well as those of oxygen addition on the microstructures, Young's moduli and tensile and fatigue properties of the two alloys were investigated. The grain diameters of the TNTZ-0.06O and TNTZ-0.14O decrease from 27 mu m (as-received) to 1.7 mu m and from 33 mu m (as-received) to 1.0 mu m, respectively, after subjected to cold swaging and the subsequent heat-treatment. These results suggest that cold swaging, followed by heat treatment, is effective in refining the grains of TNTZ alloys. However, a beta (110) texture develops in the alloys as a result of the cold swaging. Young's moduli of as-cold swaged and heat-treated TNTZ-0.06O and TNTZ-0.14O are within the range of 61-68 GPa and as low as those of solutionized TNTZ-0.06O and TNTZ-0.14O. The tensile strengths and elongations of the as-cold swaged, heat-treated and solutionized TNTZ-0.14O are approximately 30% higher and 20% lower, respectively, than those of the corresponding TNTZ-0.06O. Moreover, the 0.2% proof stresses of the heat-treated TNTZ-0.14O are approximately 110% higher than that of the corresponding TNTZ-0.06O. On the other hand, the values of the Hall-Petch constant (k) for the TNTZ-0.06O (k(TNTZ-0.06O) = 0.02) and TNTZ-0.14O (k(TNTZ-0.14O) = 0.005) are much smaller than those for pure Ti and another beta-type Ti alloy (Ti-15.2Mo). These results indicate that the addition of oxygen can improve the tensile properties of TNTZ alloys. However, the grain refinement caused by cold swaging and a subsequent heat-treatment does not have a significant effect on the tensile properties of TNTZ. The fatigue limit of the heat-treated TNTZ-0.14O (540 MPa) is much higher than those of the heat-treated and solutionized TNTZ-0.06O (290 and 230 MPa) and solutionized TNTZ-0.14O (330 MPa). These results indicated that it is possible to improve the fatigue properties of solutionized TNTZ using grain refinement, which can be induced by cold swaging and a subsequent heat-treatment and by the addition of oxygen.
  • Ken Cho; Mitsuo Niinomi; Masaaki Nakai; Junko Hieda; Xiaojie Tao
    MATERIALS TRANSACTIONS JAPAN INST METALS 54 (8) 1295 - 1301 1345-9678 2013/08 [Refereed]
     
    This work presents a study on the relationship between the alloying elements such as niobium (Nb), tantalum (Ta) or zirconium (Zr) and the hydroxyapatite (HAp) formability on the surfaces of titanium (Ti) alloys subjected to alkali treatment process that is developed to form a HAp layer. The HAp formability on the surfaces of pure Ti, Ti Nb alloys, Ti Ta alloys, Ti Zr alloys, pure Nb, pure Ta and pure Zr subjected to alkali treatment in 1 mol/L NaOH solution at 363 K for 259.2 ks was investigated. The pure Ti, Ti-10Nb alloy and Ti-10Zr alloy have a good HAp formability because sodium titanate is formed on the surface after the alkali treatment. However, the HAp formability is decreased with increasing Nb and Zr contents. A layer including sodium titanate and sodium tantalate is formed on the surfaces of Ti Ta alloys after the alkali treatment Therefore, the Ti-10Ta, Ti-20Ta, Ti-30Ta and Ti-40Ta alloys have a good HAp formability. On the other hand, a sodium niobate layer and a thick crystalline sodium tantalate layer are formed on the surfaces of pure Nb and pure Ta, respectively, after the alkali treatment Moreover, there is no component change on the surface of pure Zr after the alkali treatment. Therefore, the HAp formability on the surfaces of pure Nb, pure Ta and pure Zr is significantly low after they are soaked in a simulated body fluid for 1 week.
  • Qiang Li; Mitsuo Niinomi; Junko Hieda; Masaaki Nakai; Ken Cho
    ACTA BIOMATERIALIA ELSEVIER SCI LTD 9 (8) 8027 - 8035 1742-7061 2013/08 [Refereed]
     
    For spinal-fixation applications, implants should have a high Young's modulus to reduce springback during operations, though a low Young's modulus is required to prevent stress shielding for patients after surgeries. In the present study, Ti-29Nb-13Ta-4.6Zr alloy (TNTZ) with a low Young's modulus was modified by adding Cr to obtain a higher deformation-induced Young's modulus in order to satisfy these contradictory requirements. Two newly designed alloys, TNTZ-8Ti-2Cr and TNTZ-16Ti-4Cr, possess more stable beta phases than TNTZ. These alloys consist of single beta phases and exhibit relatively low Young's moduli of <65 GPa after solution treatment. However, after cold rolling, they exhibit higher Young's moduli owing to a deformation-induced omega-phase transformation. These modified TNTZ alloys show significantly less springback than the original TNTZ alloy based on tensile and bending loading-unloading tests. Thus, the Cr-added TNTZ alloys are beneficial for spinal-fixation applications. (C) 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
  • Junko Hieda; Mitsuo Niinomi; Masaaki Nakai; Ken Cho; Shigeki Nagai
    MATERIALS TRANSACTIONS JAPAN INST METALS 54 (8) 1361 - 1367 1345-9678 2013/08 [Refereed]
     
    In order to improve the mechanical properties of Ti-29Nb-13Ta-4.6Zr (TNTZ) alloy without increasing Young's modulus for application in bone prostheses, dispersion strengthening of TNTZ using yttrium oxide (Y2O3) particles was studied. The formation of well-dispersed Y2O3 particles inside grains of Y-added TNTZ is achieved through the reaction of added Y with the oxygen contained in TNTZ. The size and its standard deviation of obtained Y2O3 particles increased at Y concentrations of 0.2 and 0.5 mass%. The addition of Y led to a decrease in the grain size in Y-added TNTZ. Low Young's modulus was retained in the Y-added TNTZ subjected to cold rolling. The tensile strength and 0.2% proof stress slightly increased in Y-added TNTZ with Y concentrations below 0.1 mass%, whereas they decreased significantly in Y-added TNTZ with Y concentrations of 0.2 and 0.5 mass%. Large Y2O3 particles that formed in Y-added TNTZ with Y concentrations of 0.2 and 0.5 mass% worked as sources for the formation of voids during fracture, which resulted in a decrease in the tensile strength and 0.2% proof stress. Elongation tended to decrease in the Y-added TNTZ as compared to that of TNTZ without any Y addition. As a result, it is found that Y-added TNTZ with improved mechanical properties was obtained at a Y concentration of 0.05 mass% in this experiment. The fatigue strength of Y-added TNTZ was also improved at the Y concentration of 0.05 mass%.
  • H. Yilmazer; M. Niinomi; M. Nakai; K. Cho; J. Hieda; Y. Todaka; T. Miyazaki
    MATERIALS SCIENCE & ENGINEERING C-MATERIALS FOR BIOLOGICAL APPLICATIONS ELSEVIER SCIENCE BV 33 (5) 2499 - 2507 0928-4931 2013/07 
    The effect of high-pressure torsion (HPT) processing on the microstructure and mechanical biocompatibility includes Young's modulus, tensile strength, ductility, fatigue life, fretting fatigue, wear properties and other functionalities such as super elasticity and shape memory effect, etc. at levels suitable for structural biomaterials used in implants that replace hard tissue in the broad sense (Sumitomo et al., 2008 [4]). In particular, in this study, the mechanical biocompatibility implies a combination of great hardness and high strength with an adequate ductility while keeping low Young's modulus of a novel Ti-29Nb-13Ta-4.6Zr (TNTZ) for biomedical applications at rotation numbers (N) ranging from 1 to 60 under a pressure of 1.25 GPa at room temperature was systematically investigated in order to increase its mechanical strength with maintaining low Young's modulus and an adequate ductility. TNTZ subjected to HPT processing (TNTZ(HPT)) at low N exhibits a heterogeneous microstructure in micro-scale and nano-scale consisting of a matrix and a non-etched band, which has nanosized equiaxed and elongated single beta grains, along its cross section. The grains exhibit high dislocation densities, consequently non-equilibrium grain boundaries, and non-uniform subgrains distorted by severe deformation. At high N which is N>20, TNTZ(HPT) has a more homogeneous microstructure in nano-scale with increasing equivalent strain, cm Therefore, TNTZ(HPT) at high N exhibits a more homogenous hardness distribution. The tensile strength and 0.2% proof stress of TNTZ(HPT) increase significantly with N over the range of 0 <= N <= 5, and then become saturated at around 1100 MPa and 800 MPa at N >= 10. However, the ductility of TNTZ(HPT) shows a reverse trend and a low-level elongation, at around 7%. And, Young's modulus of TNTZ(HPT) decreases slightly to 60 GPa with increasing N and then becomes saturated at N >= 10. These obtained results confirm that the mechanical strength of TNTZ can be improved while maintaining a low Young's modulus in single beta grain structures through severe plastic deformation. (C) 2013 Elsevier B.V. All rights reserved.
  • Junko Hieda; Mitsuo Niinomi; Masaaki Nakai; Hiroyuki Kamura; Harumi Tsutsumi; Takao Hanawa
    Journal of Biomedical Materials Research - Part B Applied Biomaterials 101 (5) 776 - 783 1552-4973 2013/07 [Refereed]
     
    The number of hydroxyl groups on a Ti-29Nb-13Ta-4.6Zr (TNTZ) alloy surface was controlled through H2O2 treatment for further improvement of the adhesive strength and durability against water of TNTZ/silane layers (SILs)/segmented polyurethane (SPU) composites. The effect of the terminal functional groups on the adhesive strength of SPU on TNTZ, and the adhesiveness of SPU on TNTZ against water was investigated. Three types of silane-coupling agents were used to bind TNTZ and SPU: methacryloxypropyltrimethoxysilane (γ-MPTS), aminopropyltriethoxysilane (APS), and mercaptopropyltrimethoxysilane (γ-MPS). The adhesive strength of each composite was evaluated by shear bonding tests. The number of hydroxyl groups increases with an increase in treatment time at a H2O 2 concentration of 5% (v/v). On the other hand, an increase from 5% (v/v) to 30% (v/v) in H2O2 concentration leads to a decrease in the number of hydroxyl groups on the TNTZ surface because at higher H2O2 concentrations, the reaction that consumes the hydroxyl groups is dominant. The shear bonding strength is doubled compared with the untreated TNTZ/SIL/SPU interface. Although the shear bonding strength decreases after immersion in water for 30 days when APS and γ-MPS are used, TNTZ/γ-MPTS/SPU composites exhibit good durability to water and maintain an equivalent shear bonding strength before immersion in water. © 2013 Wiley Periodicals, Inc.
  • Chiaki Sato; Toru Nakano; Atsuhiro Nakagawa; Masato Yamada; Hiroaki Yamamoto; Takashi Kamei; Go Miyata; Akira Sato; Fumiyoshi Fujishima; Masaaki Nakai; Mitsuo Niinomi; Kazuyoshi Takayama; Teiji Tominaga; Susumu Satomi
    DIGESTIVE ENDOSCOPY WILEY-BLACKWELL 25 (3) 255 - 263 0915-5635 2013/05 
    Background and Aim A current drawback of endoscopic submucosal dissection (ESD) for early-stage gastrointestinal tumors is the lack of instruments that can safely assist with this procedure. We have developed a pulsed jet device that can be incorporated into a gastrointestinal endoscope. Here, we investigated the mechanical profile of the pulsed jet device and demonstrated the usefulness of this instrument in esophageal ESD in swine. Methods The device comprises a 5-Fr catheter, a 14-mm long stainless steel tube for generating the pulsed water jet, a nozzle and an optical quartz fiber. The pulsed water jet was generated at pulse rates of 3Hz by irradiating the physiological saline (4 degrees C) within the stainless steel tube with an holmium-doped yttrium-aluminum-garnet (Ho:YAG) laser at 1.1J/pulse. Mechanical characteristics were evaluated using a force meter. The device was used only for the part of submucosal dissection in the swine ESD model. Tissues removed using the pulsed jet device and a conventional electrocautery device, and the esophagus, were histologically examined to assess thermal damage. Results The peak impact force was observed at a stand-off distance of 40mm (1.1J/pulse). ESD using the pulsed jet device was successful, as the tissue specimens showed precise dissection of the submucosal layer. The extent of thermal injury was significantly lower in the dissected bed using the pulsed jet device. Conclusion The results showed that the present endoscopic pulsed jet system is a useful alternative for a safe ESD with minimum tissue injury.
  • Toshikazu Akahori; Mitsuo Niinomi; Masaaki Nakai; Harumi Tsutsumi; Shiro Aki; Yoshio Itsumi; Shogo Murakami; Hideto Oyama
    MATERIALS TRANSACTIONS JAPAN INST METALS 54 (5) 783 - 790 1345-9678 2013/05 [Refereed]
     
    The effects of various heat treatments on the microstructure and mechanical properties of an (alpha + beta)-type titanium alloy, Ti-4.5Al-2Mo-1.6V-0.5Fe-0.3Si-0.03C (KS Ti-9), were investigated systematically for possible use in next-generation aircraft applications. The as-received KS Ti-9 shows strong anisotropy of mechanical strength derived from the intense texture (T-texture) of the primary alpha phase. This anisotropy continues to be observed in KS Ti-9 annealed at a temperature below beta transus followed by air cooling, but the anisotropy drastically decreases in KS Ti-9 when subjected to a duplex heat treatment, that is, when the as-received material of KS Ti-9 is sequentially heated to a temperature slightly below beta transus followed by water quenching and then annealed followed by air cooling. It is considered that the reduction in the anisotropy in KS Ti-9 subjected to this duplex heat treatment is associated with the difference in the orientation of the precipitated acicular alpha phase.
  • Junko Hieda; Mitsuo Niinomi; Masaaki Nakai; Ken Cho; Tatsuya Gozawa; Hirokazu Katsui; Rong Tu; Takashi Goto
    JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS ELSEVIER SCIENCE BV 18 232 - 239 1751-6161 2013/02 [Refereed]
     
    Hydroxyapatite (HAp) films were deposited on a beta-type titanium alloy, Ti-29Nb-13Ta-4.6Zr (TNTZ), by metal organic chemical vapor deposition (MOCVD) in order to improve its hard-tissue compatibility. The surface morphologies of TNTZ substrates were changed by acid treatments and mechanical polishing prior to the HAp film deposition. The adhesive strength of the HAp films formed on TNTZ substrates treated with an HF solution increased to twice that of the HAp film deposited on a TNTZ substrate with a mirror-like finish. Complex microstructures with deeply etched grain boundaries, formed on the TNTZ substrates after immersion in the HF solution, were responsible for the increase in the adhesive strength of the HAp film caused by an interlocking effect. The HAp films on TNTZ substrates treated with a H2SO4 solution exhibited lower adhesive strength than HAp films on TNTZ substrates treated with HF solution, regardless of the surface roughness of the substrates. Additionally, acid treatments using HNO3 and H2O2 solutions did not change the surface morphologies of the TNTZ substrates. The complex microstructures with deeply etched grain boundaries and nanosized asperities formed on the TNTZ substrates are important factors in the improvement of the adhesive strengths of HAp films deposited on TNTZ substrates. (C) 2012 Elsevier Ltd. All rights reserved.
  • J.Hieda; M. Niinomi; M. Nakai; K. Cho
    Advances in Biomaterials Science and Biomedical Applications,InTech 515 - 538 2013 [Refereed]
  • M. Nakai; M. Niinomi; X. L. Zhao; X. F. Zhao
    MEDICAL DEVICE MATERIALS VI ASM INTERNATIONAL 165 - 168 2013 [Refereed]
     
    Titanium and its alloys are widely utilized for biomedical applications because of their high specific strength, corrosion resistance, and biocompatibility. In the past two decades, many researchers gave an effort to achieve a low Young's modulus for such the titanium alloys. However, Young's modulus of the metallic spinal rod that is one of the main components of spinal fixation devices should be not only low to prevent stress shielding effect for patients but also high to suppress springback for surgeons. Therefore, a novel function of biomedical titanium alloys, which is self-adjustment of Young's modulus, has been proposed recently by the authors. Deformation-induced phase transformation was introduced into beta-type titanium alloys to control the Young's modulus at only deformed parts, while the Young's modulus at the non-deformed parts would remain low. In this case, the Young's modulus at the deformed parts depends on the type of deformation-induced phase. Therefore, the Young's modulus change due to deformation was investigated using several types of beta-type titanium alloys. After deformation, the Young's modulus could be increased successfully by deformation-induced omega phase transformation, but was not increased by deformation-induced alpha' phase transformation.
  • T. Akahori; M. Niinomi; M. Nakai; H. Yilmazer; H. Fukui; Y. Todaka
    MEDICAL DEVICE MATERIALS VI ASM INTERNATIONAL 27 - 30 2013 [Refereed]
     
    The tensile strengths of TNTZ after solution treatment (TNTZ(ST)) or after cold rolling (TNTZ(CR)) decrease with an increase in the aging temperature, although the elongation shows the reverse trend. The fatigue limits of TNTZ(CR) subjected to aging at 673 K and 723 K are nearly equal to that of Ti-6Al-4V ELI, which has around 800 MPa. The tensile strength of TNTZ(CR) is improved drastically through high pressure torsion (HPT), which is one of severe deformation processes (SDP), and shows more than 1 GPa, although the fatigue strength is not improved by HPT because of the work-softening during the cyclic deformation.
  • Mechanical properties of Ti-12Cr alloy with self-tunable Young's modulus for use in spinal fixation devices
    M. Nakai; M. Niinomi; J. Hieda; K. Cho
    Proceedings of the 8th Pacific Rim International Congress on Advanced Materials and Processing CD-ROM 1541 - 1546 2013
  • Deformation induced changeable Young's modulus in ternary Ti-Cr-O alloys for spinal fixation applications
    H.H Liu; M. Niinomi; M. Nakai; J. Hieda; K. Cho
    Proceedings of the 8th Pacific Rim International Congress on Advanced Materials and Processing CD-ROM 1635 - 1641 2013
  • Microstructural control and mechanical properties of low-cost titanium alloys for next generation aircrafts
    M. Niinomi; M; Nakai, Itsumi; S. Murakami; H. Oyama; W. Abe; J. Hieda; K. Cho
    Proceedings of the 8th Pacific Rim International Congress on Advanced Materials and Processing CD-ROM 1131 - 1138 2013
  • Mechanical properties of low-cost beta-type Ti-Mn alloys fabricated by metal injection molding
    K. Cho; M. Niinomi; M. Nakai; J. Hieda; P.F. Santos; Y. Itoh; M. Ikeda
    Proceedings of the 8th Pacific Rim International Congress on Advanced Materials and Processing CD-ROM 1115 - 1122 2013
  • M. Nakai; M. Niinomi; J. Hieda; K. Cho; K. Komine; H. Fujii; Y. Morisada; Y. Ito; T. Konno; Y. Itsumi; H. Oyama; W. Abe
    PROCEEDINGS OF THE 1ST INTERNATIONAL JOINT SYMPOSIUM ON JOINING AND WELDING WOODHEAD PUBL LTD 429 - 434 2013 
    Welding is an important technology for using titanium alloy plates in aerospace applications. However, pores (welding defects) are introduced into the welded zone during welding, including during the melting process, leading to a decrease in the fatigue strength of the welded titanium alloy joint. Friction stir welding (FSW) seems to be effective for avoiding the deterioration of fatigue strength because it is difficult for pores to form in the welded zone during FSW, which does not include a melting process. Therefore, the microstructure and mechanical properties, including the fatigue properties, of an (alpha+beta)-type titanium alloy, Ti-4.5Al-2.5Cr-1.2Fe-0.1C alloy (Ti-531C), subjected to FSW were investigated. In this study, FSW was conducted from both sides of the plates (double-sided FSW) to ensure that the samples were subjected to the same experimental conditions (plate thickness, specimen geometry, etc.) used in our previous study on laser-welded Ti-531C plates for comparison. No pores are observed on the fractured surfaces of Ti-531C subjected to double-sided FSW. Consequently, higher fatigue strength is obtained for Ti-531C subjected to double-sided FSW compared with the samples subjected to double-sided laser welding. However, an acicular secondary alpha phase and a grain-boundary alpha phase in the first welded zone are coarsened by heating in the second welded zone, leading to a difference in hardness in the direction of the loading axis for the fatigue test. As a result, the boundary between these two regions became a stress-concentration site that deteriorates the fatigue strength of Ti-531C subjected to double-sided FSW.
  • Xiu Song; Lei Wang; Mitsuo Niinomi; Masaaki Nakai; Yang Liu; Miaoyong Zhu
    Materials Science Forum 750 147 - 151 0255-5476 2013 [Refereed]
     
    The microstructures and mechanical properties of the TNTZ added with Y or Y2O3 have been investigated. The results indicate that TNTZ added with Y or 2O3 are found to be composed of β phase and the small amount of 2O3. The grain size of TNTZ added with Y or 2O3 is smaller than that of TNTZ. The Young's modulus of TNTZ added with Y or 2O3 are maintained at a low level, and Young's modulus of TNTZ added with Y is smaller than that of TNTZ added with 2O3. The mechanical properties are both improved by adding Y or 2O3, while the tensile strength of TNTZ added with 2O3 is slightly higher than that of TNTZ added with Y. The high cycle fatigue limit of the alloys added with Y or 2O3 are similar, while the low cycle fatigue strength of TNTZ added with Y is higher than that of TNTZ with 2O3. The improving of mechanical properties ascribes to the microstructure refinement and the pining effect of 2O3 particles. On the other hand, Y elements form 2O3 with the oxygen elements in the matrix, thus lead to the weakening of the oxygen solution effect. © (2013) Trans Tech Publications, Switzerland.
  • Shinji Takemoto; Masaaki Nakai; Masayuki Hattori; Masao Yoshinari; Eiji Kawada; Mitsuo Niinomi; Yutaka Oda
    Key Eng. Mater. TRANS TECH PUBLICATIONS LTD 529-530 584 - 587 1013-9826 2013 [Refereed]
     
    The objective of this study was to evaluate the corrosion behavior of Ti-29Nb-13Ta-4.6Zr alloy (TNTZ) with immersion in an acidic saline solution containing fluoride by investigating change in color and the surface structure of the oxide film. With immersion in fluoride-containing solution, TNTZ showed a less marked change in color than commercially pure titanium (TI), and a smaller decrease in glossiness. The outermost surface was covered with oxides from its constituent elements at before and after immersion in solution with or without fluoride. When immersed in fluoride-containing solution, the film consisted of larger niobium and tantalum oxides than that before or after immersion in solution without fluoride. In summary, TNTZ showed superior resistance to discoloration to TI after immersion in fluoride-containing solution. The results suggest that the subsequent increase in niobium and tantalum fractions in the oxide film in TNTZ improves resistance to corrosion.
  • Mitsuo Niinomi; Masaaki Nakai; Junko Hieda; Ken Cho; Toshikazu Akahori; Tomokazu Hattori; Masahiko Ikeda
    Key Eng. Mater. TRANS TECH PUBLICATIONS LTD 551 133 - 139 1013-9826 2013 [Refereed]
     
    beta-type titanium alloys comprising low cost elements such as Fe, Mn, Cr, Sn, Al, O and N and having low Young's modulus are currently being developed. Examples of such alloys include Ti-10Cr-Al, Ti-Mn, Ti-Mn-Fe, Ti-Mn-Al, Ti-Cr-Al, Ti-Sn-Cr, Ti-Cr-Sn-Zr, Ti-(Cr, Mn)-Sn, and Ti-12Cr. Ti-5Fe-3Nb-3Zr belongs to that class of titanium alloys in which rare metals such as Nb, Ta, and Zr have been reduced using Fe. Ti-5Fe-3Nb-3Zr has a Young's modulus of around 76 GPa and has greater strength than that of Ti-6Al-4V ELI for biomedical applications. The characteristics of Ti-5Fe-3Nb-3Zr and other low-cost beta-type titanium alloys with low Young's moduli are discussed from the viewpoint of biomedical applications.
  • Masaaki Nakai; Mitsuo Niinomi; Junko Hieda; Ken Cho; Toshikazu Akahori; Kazuhiro Hayashi; Yoshio Itsumi; Shogo Murakami; Hideto Oyama
    MATERIALS TRANSACTIONS JAPAN INST METALS 54 (2) 169 - 175 1345-9678 2013 [Refereed]
     
    The effects of interstitial carbon solute and titanium carbide on the tensile and fatigue properties of an (alpha+beta)-type titanium alloy, Ti-4.5Al-2.5Cr-1.2Fe-0.1C (KS Ti-531C), with bimodal and Widmanstatten alpha structures were investigated. In order to control the microstructures, this alloy was subjected to annealing at temperatures just below and just above the beta-transus (531C-alpha+beta annealed and 531C-beta annealed, respectively). The microstructure of 531C-alpha+beta annealed shows a bimodal structure and any titanium carbide is not observed, whereas that of 531C-beta annealed shows a Widmanstatten alpha structure and some titanium carbides, which are considered to be Ti2C, are observed. The tensile strength and elongation of 531C-alpha+beta annealed and 531C-beta annealed are similar, but 0.2% proof stress is higher and further the reduction of area is much larger for 531C-alpha+beta annealed than 531C-beta annealed. Their tensile properties depend mainly on the type of microstructure and interstitial element partitioning because the titanium carbide is not observed on the fractured surfaces of both the alloys after tensile tests. Also, the fatigue properties of 531C-alpha+beta annealed are better than those of 531C-beta annealed. The titanium carbide is observed on the fractured surface of 531C-beta annealed, but not observed on that of 531C-alpha+beta annealed, after fatigue tests. Therefore, titanium carbide is considered to cause deterioration in the fatigue properties of 531C-beta annealed compared to those of 531C-alpha+beta annealed.
  • Ken Cho; Mitsuo Niinomi; Masaaki Nakai; Junko Hieda; Yuuki Kawasaki
    Materials Transactions 54 (4) 574 - 581 1345-9678 2013 [Refereed]
     
    TiFeCu alloys with higher Young's modulus, hardness and compressive mechanical properties than those of the existing Ti alloys were developed using a d-electrons alloy design method in order to improve Young's modulus, hardness and compressive properties of Ti and existing Ti alloys for use as metallic stents. Their microstructures, Young's modulus, hardness and compressive mechanical properties were investigated both before (as-cast) and after heat-treatments performed under a high-purity argon atmosphere at 1173K for 21.6 and 86.4 ks. The studied TiFeCu alloys consist of the β-Ti phase and dendritic TiFe intermetallic phase. Moreover, the area fraction of the TiFe intermetallic phase increases with increasing atom ratio (Fe + Cu)/Ti of the alloys and with the heat-treatment time. The Young's modulus of the studied TiFeCu alloys increases from 110 GPa (Ti78Fe18Cu 4 alloy) to 145 GPa (Ti68Fe30Cu2 alloy) with increasing atom ratio (Fe + Cu)/Ti of the alloys and the area fraction of the TiFe intermetallic phase. However, the Young's modulus is saturated or slightly decreased when the area fraction of the TiFe intermetallic phase is more than 34%. The Vickers hardness of the as-cast alloys increases from 490HV (Ti78Fe18Cu4 alloy to 550HV (Ti 63.4Fe30Cu6.6 alloy with increasing atom ratio (Fe + Cu)/Ti of the alloys and area fraction of the TiFe intermetallic phase. On the other hand, the Vickers hardness of the heat-treated alloys is lower than that of the as-cast alloys, despite the increase in the area fraction of the TiFe intermetallic phase after the heat-treatment. The heat-treated alloys have better compressive properties than those of the as-cast alloys and the reported TiFeCu alloys. The compressive strength and strain of the heat-treated Ti67Fe27Cu6 alloys reach to 2131MPa and 24.5%, respectively. © 2013 The Japan Institute of Metals.
  • M. Nakai; M. Niinomi; J. Hieda; H. Yilmazer; Y. Todaka
    Scientia Iranica Elsevier BV 20 (3) 1067 - 1070 1026-3098 2013/01
  • Akiko Obata; Eri Miura-Fujiwara; Akimitsu Shimizu; Hirotaka Maeda; Masaaki Nakai; Yoshimi Watanabe; Mitsuo Niinomi; Toshihiro Kasuga
    ADVANCES IN MATERIALS SCIENCE AND ENGINEERING HINDAWI PUBLISHING CORPORATION 2013 Article ID 501621  1687-8434 2013 [Refereed]
     
    Ti-29Nb-13Ta-4.6Zr (TNTZ) alloy has excellent mechanical properties and bone conductivity. For dental application, TNTZ surfaces were converted to white oxidized layer by a simple heat treatment in air to achieve the formation of aesthetic surfaces. The oxidized layer formed by the heat treatment at 1000 degrees C for 0.5 or 1 hr was whiter and joined to TNTZ substrate more strongly than that formed by the treatment at 900 degrees C. The layer consisted of TiO2 (rutile), TiNb2O7, and TiTa2O7 and possessed similar to 30 mu m in thickness for the sample heat-treated at 1000 degrees C and similar to 10 mu m for that heat-treated at 900 degrees C. The surface average roughness and the wettability increased after the heat treatment. The spreading and proliferation level of mouse osteoblast-like cell (MC3T3-E1 cell) on the heat-treated sample were almost the same as those on as-prepared one. The cell spreading on TNTZ was better than those on pure titanium (CP Ti) regardless of the heat treatment for the samples. There was no deterioration in the in vitro cell compatibility of TNTZ after the oxidized layer coating by the heat treatment.
  • 新家光雄; 服部友一; 仲井正昭
    日本骨形態計測学会雑誌 23 (1) 23 - 30 0917-4648 2013
  • Yusuke Tsutsumi; Mitsuo Niinomi; Masaaki Nakai; Harumi Tsutsumi; Hisashi Doi; Naoyuki Nomura; Takao Hanawa
    APPLIED SURFACE SCIENCE ELSEVIER SCIENCE BV 262 34 - 38 0169-4332 2012/12 [Refereed]
     
    Micro-arc oxidation (MAO) was performed on a beta-type Ti-29Nb-13Ta-4.6Zr alloy (TNTZ) in this study to improve its bioactivity in a body fluid and its hard-tissue compatibility. The surface oxide layer formed on TNTZ by MAO treatment in a mixture of calcium glycerophosphate and magnesium acetate was characterized using various surface analyses. The oxide layer was mainly composed of two types of TiO2 (rutile and anatase), and it also contained Ca, P, and Mg, which were incorporated from the electrolyte during the treatment. The calcium phosphate formation on the surface of the specimens after immersion in Hanks' solution was evaluated to determine the bioactivity of TNTZ with and without MAO treatment. As a result, thick calcium phosphate layers formed on the TNTZ specimen that underwent MAO treatment, whereas only a small amount of precipitate was observed on TNTZ without treatment. Thus, the MAO treatment is a promising method to improve the bioactivity and hard-tissue compatibility of TNTZ. (c) 2012 Elsevier B.V. All rights reserved.
  • Kengo Narita; Mitsuo Niinomi; Masaaki Nakai; Junko Hieda; Kazuya Oribe
    MATERIALS LETTERS ELSEVIER SCIENCE BV 86 178 - 181 0167-577X 2012/11 [Refereed]
     
    For implant rods as spinal fixation system, low Young's modulus, easy bending to an intended shape (low spring-back), and retaining initial bended shape during a long implantation (low aging-back) are essential properties. The rods were fabricated using a biomedical beta-type titanium alloy, Ti-29Nb-13Ta-4.6Zr alloy (TNTZ), and their above-mentioned properties were evaluated in comparison with conventional biomaterials, commercially pure titanium, Ti-6Al-4V ELI, and SUS316L stainless steel. In the results of an animal experiment using implant rods made by TNTZ subjected to solution treatment with low Young's modulus, no negative effects are seen in the radiographs, and no inflammatory cells are observed in histological observation. In spite of low Young's modulus, the spring-back of TNTZ subjected to solution treatment is comparable to that of Ti-6Al-4V ELI. Further, its aging-back is quite small among the other materials. (C) 2012 Elsevier B.V. All rights reserved.
  • Mitsuo Niinomi; Masaaki Nakai; Junko Hieda
    ACTA BIOMATERIALIA ELSEVIER SCI LTD 8 (11) 3888 - 3903 1742-7061 2012/11 [Refereed]
     
    New low modulus beta-type titanium alloys for biomedical applications are still currently being developed. Strong and enduring p-type titanium alloy with a low Young's modulus are being investigated. A low modulus has been proved to be effective in inhibiting bone atrophy, leading to good bone remodeling in a bone fracture model in the rabbit tibia. Very recently beta-type titanium alloys with a self-tunable modulus have been proposed for the construction of removable implants. Nickel-free low modulus beta-type titanium alloys showing shape memory and super elastic behavior are also currently being developed. Nickel-free stainless steel and cobalt-chromium alloys for biomedical applications are receiving attention as well. Newly developed zirconium-based alloys for biomedical applications are proving very interesting. Magnesium-based or iron-based biodegradable biomaterials are under development. Further, tantalum, and niobium and its alloys are being investigated for biomedical applications. The development of new metallic alloys for biomedical applications is described in this paper. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
  • Xingfeng Zhao; Mitsuo Niinomi; Masaaki Nakai; Junko Hieda
    MATERIALS TRANSACTIONS JAPAN INST METALS 53 (8) 1379 - 1384 1345-9678 2012/08 [Refereed]
     
    A series of metastable beta-type binary Ti-(18-22)V alloys were prepared to investigate the effect of deformation-induced products (deformation-induced omega phase transformation and mechanical twinning) on the mechanical properties of metastable beta-type titanium alloys. The microstructures, Young's moduli, and tensile properties of the alloys were systemically examined. Ti-(18-20)V alloys subjected to solution treatment comprise a beta phase and a small amount of athermal omega phase, while Ti-22V alloy subjected to solution treatment consists of a single beta phase. Ti-(18-20)V alloys subjected to solution treatment exhibit relatively low Young's moduli and low tensile strengths as compared to cold-rolled specimens. Both deformation-induced omega phase transformation and {332}(beta)< 113 >(beta) mechanical twinning occur in all of the alloys during cold rolling. The occurrences of {332}(beta)(113)(beta) mechanical twinning and deformation-induced omega phase transformation are dependent on the beta stability of the alloys. After cold rolling, all of the alloys comprise a beta phase and an omega phase. The Young's moduli of Ti-(18-22)V alloys increase because of the formation of a deformation-induced omega phase during cold rolling. The significant increase in tensile strength is attributed to the combined effect of the deformation-induced omega phase transformation and work-hardening during cold rolling. [doi: 10.2320/matertrans.M2012116]
  • Xingfeng Zhao; Mitsuo Niinomi; Masaaki Nakai; Junko Hieda; Takuya Ishimoto; Takayoshi Nakano
    ACTA BIOMATERIALIA ELSEVIER SCI LTD 8 (6) 2392 - 2400 1742-7061 2012/07 [Refereed]
     
    Metallic implant rods used in spinal fixtures should have a Young's modulus that is sufficiently low to prevent stress shielding for the patient and sufficiently high to suppress springback for the surgeon. Therefore, we propose a new concept: novel biomedical titanium alloys with a changeable Young's modulus via deformation-induced to phase transformation. In this study, the Cr content in the range of 10-14 mass% was optimized to produce deformation-induced omega phase transformation, resulting in a large increase in the Young's modulus of binary Ti-Cr alloys. The springback and cytotoxicity of the optimized alloys were also examined. Ti-(10-12)Cr alloys exhibit an increase in Young's modulus owing to deformation-induced omega phase transformation. In this case, such deformation-induced omega phase transformation occurs along with {332}(beta) mechanical twinning, resulting in the maintenance of acceptable ductility with relatively high strength. Among the examined alloys, the lowest Young's modulus and largest increase in Young's modulus are obtained from the Ti-12Cr alloy. This alloy exhibits smaller springback than and comparable cytocompatibility to the biomedical Ti alloy Ti-29Nb-13Ta-4.6Zr. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
  • Masaaki Nakai; Mitsuo Niinomi; Toshikazu Akahori; Kazuhiro Hayashi; Yoshio Itsumi; Shogo Murakami; Hideto Oyama; Wataru Abe
    MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING ELSEVIER SCIENCE SA 550 (2) 55 - 65 0921-5093 2012/07 [Refereed]
     
    The complex microstructure of a high hot-workable alpha + beta-type titanium alloy, Ti-4.5Al-2.5Cr-1.2Fe-0.1C with a continuously varying alpha phase in terms of its size, distribution, morphology, and crystal orientation from the welded zone to the matrix, including a trace amount of welding defect, was investigated by several microstructural and crystallographical analysis techniques such as optical microscopy, scanning electron microscopy, and X-ray diffraction to elucidate the crucial factors determining its mechanical properties such as tensile properties and fatigue etc. The alloy was processed with laser welding to prepare parts for use in next-generation aircraft. The tensile properties of welded samples exhibit a strength-ductility balance similar to that of non-welded sample. All the failures in these samples occur at their matrices because the hardness values of welded zone on the cross section perpendicular to loading direction of the welded samples are higher than that on the same plane of non-welded sample, which is related to crystal texture of alpha phase. However, the fatigue strengths of welded samples are lower than that of non-welded sample. Such the decrease in fatigue strength of welded samples is caused by the presence of pores formed during welding. (c) 2012 Elsevier B.V. All rights reserved.
  • H. Yilmazer; M. Niinomi; M. Nakai; J. Hieda; Y. Todaka; T. Akahori; T. Miyazaki
    JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS ELSEVIER SCIENCE BV 10 235 - 245 1751-6161 2012/06 
    A novel beta-type titanium alloy, Ti-29Nb-13Ta-4.6Zr (TNTZ), has been developed as a candidate for biomedical applications. TNTZ exhibits non-toxicity and a low Young's modulus close to that of bone (10-30 GPa). Such a low Young's modulus of this alloy is achieved by comprising a single metastable beta phase. Greater mechanical biocompatibility, which implies higher mechanical strength and hardness while maintaining a low Young's modulus, has been aimed for TNTZ. Therefore, strengthening by grain refinement and increasing dislocation density is expected to provide TNTZ high mechanical strength while keeping a low Young's modulus because they keep the original beta phase. In this case, high-pressure torsion (HPT) processing is one of the effective ways to obtain these properties simultaneously in TNTZ. Thus, in this study, the effect of HPT processing on the microstructure and mechanical hardness of TNTZ was systematically investigated at rotation numbers (N) of 1 to 20 under a pressure of around 1.25 GPa at room temperature. On the cross sections of TNTZ subjected to HPT processing (TNTZ(HPT)) after cold rolling (TNTZ(CR)) at any rotation number, a heterogeneous microstructure consisting of a matrix and a non-etched band, which is not corroded by etching solution, can be observed. The thickness of non-etched band increases as rotation number and distance from specimen center increase. Both matrix and non-etched band comprise a single beta phase, but their grain geometries are different each other. Equiaxed grains and elongated grains are observed in the matrix and the non-etched band, respectively. The equiaxed grain diameter, which is ranged from 155 nm to 44 nm, in the matrix decreases with increasing rotation number. Contrastingly, the elongated grains with a length of around 300 nm and a width of 30 nm, which are nearly constant with rotation number, are observed in the non-etched band. The mechanical hardness of TNTZ(HPT) is consistently much higher than that of TNTZ(CR). The mechanical hardness distribution on the surface of TNTZ(HPT) is heterogeneous in the radial and depth directions, while that of TNTZ(CR) is homogeneous; the mechanical hardness is higher in the peripheral region than in the central region on the surfaces of TNTZ(HPT) at all N. Further, the mechanical hardness distribution on the cross sections of TNTZ(HPT) at all N is also heterogeneous in depth direction; the mechanical hardness is higher in the peripheral region than in the central region. The heterogeneous mechanical hardness distribution depending on the position on the surface and cross section of TNTZ(HPT) is considered to be related to grain refinement and imposed strain due to HPT processing. (C) 2012 Elsevier Ltd. All rights reserved.
  • Xingfeng Zhao; Mitsuo Niinomi; Masaaki Nakai; Junko Hieda
    ACTA BIOMATERIALIA ELSEVIER SCI LTD 8 (5) 1990 - 1997 1742-7061 2012/05 [Refereed]
     
    To develop a novel biomedical titanium alloy with a changeable Young's modulus via deformation-induced omega phase transformation for the spinal rods in spinal fixation devices, a series of metastable beta type binary Ti-(15-18)Mo alloys were prepared. In this study, the microstructures, Young's moduli and tensile properties of the alloys were systemically examined to investigate the effects of deformation-induced omega phase transformation on their mechanical properties. The springback of the optimal alloy was also examined. Ti-(15-18)Mo alloys subjected to solution treatment comprise a beta phase and a small amount of athermal omega phase, and they have low Young's moduli. All the alloys investigated in this study show an increase in the Young's modulus owing to deformation-induced omega phase transformation during cold rolling. The deformation-induced omega phase transformation is accompanied with {332}(beta) mechanical twinning. This resulted in the maintenance of acceptable ductility with relatively high strength. Among the examined alloys, the Ti-17Mo alloy shows the lowest Young's modulus and the largest increase in the Young's modulus. This alloy exhibits small springback and could be easily bent to the required shape during operation. Thus, Ti-17Mo alloy is considered to be a potential candidate for the spinal rods in spinal fixation devices. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
  • Kengo Narita; Mitsuo Niinomi; Masaaki Nakai; Junko Hieda; Kazuya Oribe
    JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS ELSEVIER SCIENCE BV 9 207 - 216 1751-6161 2012/05 [Refereed]
     
    The mechanical strength of a beta titanium alloy such as Ti-Nb-Ta-Zr alloy (TNTZ) can be improved significantly by thermo-mechanical treatment. In this study, TNTZ was subjected to solution treatment, cold caliber rolling, and cold swaging before aging treatment to form a rod for spinal fixation. The {110}(beta) are aligned parallel to the cross-section with two strong peaks approximately 180 degrees apart, facing one another, in the TNTZ rods subjected to cold caliber rolling and six strong peaks at approximately 60 degrees intervals, facing one another, in the TNTZ rods subjected to cold swaging. Therefore, the TNTZ rods subjected to cold swaging have a more uniform structure than those subjected to cold caliber rolling. The orientation relationship between the alpha and beta phases is different. A |110|(beta)/|121|(alpha), (112)beta//(210)alpha orientation relationship is observed in the TNTZ rods subjected to aging treatment at 723 K after solution treatment and cold caliber rolling. On the other hand, a |110|(beta)//|001|(alpha), (112)(beta)//(200)(alpha) orientation relationship is observed in TNTZ rod subjected to aging treatment at 723 K after cold swaging. A high 0.2% proof stress of about 1200 MPa, high elongation of 18%, and high fatigue strength of 950 MPa indicate that aging treatment at 723 K after cold swaging is the optimal thermo-mechanical process for a TNTZ rod. (C) 2012 Elsevier Ltd. All rights reserved.
  • Yonghwan Kim; Mitsuo Niinomi; Masaaki Nakai; Toshikazu Akahori; Toru Kanno; Hisao Fukui
    JOURNAL OF ALLOYS AND COMPOUNDS ELSEVIER SCIENCE SA 519 15 - 24 0925-8388 2012/04 
    The objective of this research was to investigate the effect of constitutional phases on the unique hardening behavior of as-solutionized dental Ag-Pd-Au-Cu alloy fabricated by cold rolling. The commercial dental Ag-Pd-Au-Cu alloy fabricated by cold rolling consists of Cu-rich alpha(1), Ag-rich alpha(2), and beta phases. On the other hand, the Ag-Pd-Au-Cu alloy fabricated by the liquid rapid solidification (LRS) method consists of single alpha phase. They were subjected to various heat treatments, respectively. The microstructures were observed by scanning electron microscope, transmission electron microscope and X-ray diffraction. The hardness was evaluated by a Vickers micro-hardness tester. In the Ag-Pd-Au-Cu alloy fabricated by cold rolling, the fine L1(0)-type-ordered beta' phase is precipitated and the coarse beta phase is remained after solution treatment at 1123 K. The hardness increases drastically. On the other hand, in the Ag-Pd-Au-Cu alloy fabricated by LRS method, the single alpha phase was decomposed into the alpha(1) phase and the alpha(2) phase after solution treatment at 1023 K and its hardness change was small. However, after aging treatment at 673 K, the fine beta phase is precipitated in the alpha phase and the hardness increases greatly even in the Ag-Pd-Au-Cu alloy fabricated by LRS method. It is considered that the precipitation of the fine L1(0)type-ordered beta' phase may contribute strongly to the unique hardening in the as-solutionized dental Ag-Pd-Au-Cu alloy fabricated by cold rolling. (C) 2011 Elsevier B. V. All rights reserved.
  • Xiu Song; Mitsuo Niinomi; Masaaki Nakai; Harumi Tsutsumi; Lei Wang
    MATERIALS SCIENCE & ENGINEERING C-MATERIALS FOR BIOLOGICAL APPLICATIONS ELSEVIER SCIENCE BV 32 (3) 542 - 549 0928-4931 2012/04 [Refereed]
     
    Improvement in fatigue strength in spite of maintaining low Young's modulus was achieved in Ti-29Nb-13Ta-4.6Zr (TNTZ) by hard-particles dispersion. A certain amount of Y2O3 additions was added into TNTZ. TNTZ with 0.05-1.00mass%Y consists of a beta-phase with a small amount of Y2O3. Young's moduli of TNTZ with 0.05-1.00mass%Y are maintained low, and are almost similar to that of TNTZ without Y2O3. The tensile strength of TNTZ with 0.05-1.00mass%Y is slightly improved and the elongation does not deteriorate by Y2O3 additions. However, the 0.2% proof stress decreases with the increase in Y concentration. Although tensile properties are not changed drastically, the fatigue strength is significantly improved by Y2O3 additions. The dispersion of Y2O3 particle increases the resistance to fatigue initiation. However. Y2O3 with too large diameter at the surface of the specimen works harmfully as the fatigue initiation site. The Y2O3 diameter and volume fraction increase with the increase in Y concentration. As a result, the fatigue limit of the alloys with 0.05-1.00mass%Y firstly increases and then decreases with the increase in Y concentration. TNTZ with 0.1mass% Y exhibits the best combination of higher fatigue strength and low Young's modulus. (C) 2011 Elsevier B.V. All rights reserved.
  • Yonghwan Kim; Mitsuo Niinomi; Junko Hieda; Masaaki Nakai; Hisao Fukui
    MATERIALS SCIENCE & ENGINEERING C-MATERIALS FOR BIOLOGICAL APPLICATIONS ELSEVIER SCIENCE BV 32 (3) 503 - 509 0928-4931 2012/04 
    The relationship between the microstrucutural changes of L1(0)-type ordered beta' phase and hardening behavior in as-solutionized dental Ag-Pd-Au-Cu alloys was investigated by changing the cooling rate and the solution treatment temperature. Additionally, the formation process of the beta' phase in as-solutionized Ag-Pd-Au-Cu alloy was attempted to clarify. The microstructural changes were observed by X-ray diffraction (XRD) method and transmission electron microscopy (TEM). The hardness was evaluated using a Vickers microhardness tester. The beta' phase is precipitated regardless of the cooling rate, after solution treatment at 1123 K. TEM dark field images show that the size of the beta' phase decreases and the number of beta' phase increases with an increase in the cooling rate. The Vickers hardness value increases with an increase in cooling rate. TEM dark field images show that the microstructure of beta' phase is similar when the solution treatment temperature increases from 1123 K to 1173 K. However, the Vickers hardness increases with an increase of solution treatment temperature. It is of great significance to reveal that the beta' phase precipitated in as-solutionized Ag-Pd-Au-Cu alloy is formed during cooling after high-temperature solution treatment and that the growth of the beta' phase is diffusion controlled. (C) 2011 Elsevier B.V. All rights reserved.
  • Junko Hieda; Mitsuo Niinomi; Nakai A. Masaaki; Hiroyuki Kamura; Harumi Tsutsumi; Takao Hanawa
    SURFACE & COATINGS TECHNOLOGY ELSEVIER SCIENCE SA 206 (13) 3137 - 3141 0257-8972 2012/02 [Refereed]
     
    Composite materials that consisted of a biomedical beta-type titanium alloy, Ti-29Nb-13Ta-4.6Zr alloy (TNTZ) with low Young's modulus and segment polyurethane (SPU) have been fabricated for application in biomedical devices. The effects of different kinds of terminal functional groups and the thickness of the silane layers (SIL) on the adhesive strength between TNTZ and SPU were investigated by means of shear bonding tests. The following silane coupling agents were employed in this study: 3-methacryloxypropyltrimethoxysilane (gamma-MPTS), aminopropyltriethoxysilane CAPS), and 3-mercaptopropyltrimethoxysilane (gamma-MPS). Furthermore, the shear bonding strength of the TNTZ/SIL/SPU interface was also characterized after immersion in water for 30 d. Silane coupling treatment produces a ten-fold increase in the shear bonding strength, independent of the type of terminal functional groups and the thickness of the silane layers. Scanning electron microscopic evaluation of the fracture surfaces of the TNTZ/SIL/SPU composites after the shear bonding tests coupled with energy dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy revealed that the TNTZ/SIL/SPU composites are partially fractured at the interfaces of the TNTZ/SIL while the rest of the fracture occurs at the interfaces of the SIL/SPU in single sample. The shear bonding strength decreases after immersion in water for 30 d when APS and gamma-MPS are used as the silane coupling agents, because stable chemical bonding is not achieved between the silane layer and SPU, whereas the bonding of the gamma-MPTS composite is not affected by exposure to water. (C) 2012 Elsevier B.V. All rights reserved.
  • Qiang Li; Mitsuo Niinomi; Masaaki Nakai; Zhenduo Cui; Shengli Zhu; Xianjin Yang
    MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING ELSEVIER SCIENCE SA 536 197 - 206 0921-5093 2012/02 [Refereed]
     
    beta-Type titanium alloys with composition of Ti-24 at% Nb-(0, 2, 4) at% Zr were prepared and subjected to aging treatment for different durations. The addition of Zr suppressed the formation and growth of isothermal omega phase during aging treatment, and therefore the investigated Ti-Nb-Zr alloys with different Zr content performed various deformation mechanisms, mechanical properties and super-elastic effects with the changes of aging time. The isothermal omega phase exerted inhibitory effects on twinning and stress-induced martensitic transformation. Desirable properties were obtained in Ti-Nb-Zr alloy by adding suitable Zr content and processing short time aging treatment. Ti-24 at% Nb-2 at% Zr alloy subjected to aging treatment at 573 K for 7.2 ks exhibited an ultimate tensile strength of 710 MPa, an elongation of 13%, a Young's modulus of 64 GPa, and a super-elastic recovery strain of 4.3%. Ti-24 at% Nb-4 at% Zr alloy subjected to aging treatment at 573 K for 1.8 ks, 3.6 ks, and 7.2 ks performed a low Young's modulus of 62 GPa and ultimate tensile strength around 600 MPa. (C) 2012 Elsevier B.V. All rights reserved.
  • Mechanically bio-functional titanium alloys for substituting failed hard tissue
    M. Niinomi; M. Nakai
    FRAY INTERNATIONAL SYMPOSIUM 7 409 - 434 2012
  • Development of porous titanium filled with poly-L-lactic acid by modified in-situ polymerization technique
    M. Nakai; M. Niinomi; D. Ishii
    FRAY INTERNATIONAL SYMPOSIUM 7 453 - 464 2012
  • Improvement in fatigue strength with maintaining Young's modulus low by controlling ω-phase precipitation in β-type Ti-Nb-Ta-Zr alloy
    M. Nakai; M. Niinomi
    TI-2011: PROCEEDINGS OF THE 12TH WORLD CONFERENCE ON TITANIUM 2102 - 2105 2012 [Refereed]
  • Xingfeng Zhao; Mitsuo Niinomi; Masaaki Nakai
    TI-2011: PROCEEDINGS OF THE 12TH WORLD CONFERENCE ON TITANIUM SCIENCE PRESS BEIJING 2046 - 2049 2012 [Refereed]
     
    Nowadays, biomaterials that are used to design spinal fixtures cannot meet the requirements of both surgeons and patients; surgeons require the material to have a high Young's modulus to suppress springback during the operation, whereas patients require the material to have a low Young's modulus to prevent the stress-shielding effect. Therefore, new titanium alloys with good biocompatibility and a changeable Young's modulus require to be developed. The,, phase significantly influences the mechanical properties of titanium alloys. According to reports, the as phase can be introduced by deformation at room temperature in p-type Ti-Cr alloys. The effects of deformation-induced phases on the mechanical properties of a metastable beta-type Ti-12Cr alloy were investigated. The experimental results indicate that the Young's modulus, tensile strength, and Vickers hardness of the Ti-12Cr alloy increase remarkably by cold rolling. The transmission electron microscopy (TEM) observation of a Ti-12Cr alloy shows that deformation-induced as phase transformation occurs in the Ti-12Cr alloy during cold rolling. Therefore, the increase in the Young's modulus of the alloy after cold rolling is ascribable to the deformation-induced as phase, which is formed in the alloy during cold rolling at room temperature.
  • Improvement of mechanical strength of titanium alloys by microstructural refinement to nano-size through high pressure torsion
    M. Niinomi; M. Nakai; J. Hieda; K. Cho
    Processing and Fabrication of Advanced Materials-XXI 693 - 701 2012
  • Recently developed titanium alloys for spinal fixation applications
    M. Nakai; M. Niinomi; J. Hieda; K. Cho
    Processing and Fabrication of Advanced Materials-XXI 329 - 335 2012
  • Xiaoli Zhao; Mitsuo Niinomi; Masaaki Nakai
    TI-2011: PROCEEDINGS OF THE 12TH WORLD CONFERENCE ON TITANIUM SCIENCE PRESS BEIJING 2063 - 2066 2012 [Refereed]
     
    This research focused on development of new titanium alloys with changeable Young's modulus for spinal fixation applications by taking advantage of deformation-induced phase transformation. The microstructures, Young's moduli, and tensile properties of metastable Ti-30Zr-x(Cr, Mo) alloys subjected to solution treatment (ST) and cold rolling (CR) were investigated. During cold rolling, deformation-induced phase transformation occurs in all these alloys. The change in Young's modulus after cold rolling is highly dependent on the type of deformation-induced phase. The decrease in Young's modulus after cold rolling is attributed to the deformation-induced alpha' phase, while the increase in Young's modulus after cold rolling is attributed to the deformation-induced omega phase in {332} mechanical twinning. Ti-30Zr-3Cr-3Mo alloy exhibiting excellent tensile properties and a changeable Young's modulus is a promising candidate for spinal fixation applications.
  • Masaaki Nakai; Mitsuo Niinomi; Junko Hieda; Toshiya Shibata
    ISIJ INTERNATIONAL IRON STEEL INST JAPAN KEIDANREN KAIKAN 52 (9) 1655 - 1660 0915-1559 2012 [Refereed]
     
    Ternary beta-type Ti-10Cr-(V, Fe, Mo) alloys with self-tunable Young's moduli were subjected to solution treatment and cold rolling, and their microstructures and mechanical properties were investigated. During cold rolling, a band-like structure, which is considered to be {332},(beta)< 113 >(beta) mechanical twin, and deformation-induced omega phase are formed in alloys with certain chemical compositions. The number of bands increases with an increase in the cold-rolling reduction ratio and V content as well as with a decrease in Mo content. On the other land, the Young's modulus increases during cold rolling, and the increase in Young's modulus is considered to be caused by the deformation-induced omega phase transformation. Furthermore, the tensile strength decreases slightly and the elongation tends to increase with an increase in the alloying element contents, while the effect of the V and Mo contents on the trend in changing the number of mechanical twin is opposite. These tensile properties are derived from the complicated factors among the plastic deformation mode, the type of mechanical twinning, and deformation-induced omega phase transformation, depending on the beta stability and the kind of alloying element.
  • 椙村豊彦; 福井壽男; 新家光雄; 赤堀俊和; 仲井正昭; 稗田純子; 金容煥
    日本歯科理工学会誌 The Japanese Society for Dental Materials and Devices 31 (6) 531 - 537 1884-4421 2012 
    The relationship between the microstructure and hardness of a dental casting Au-Ag-Pd alloy, which was fabricated by the liquid rapid solidification (LRS) method, subjected to re-solidification with two types of cooling rate, i.e., water-quenched and air-cooled solidifications, or a solution treatment at a high temperature after those were investigated based on the β phase precipitation behavior in this study. The following conclusions were obtained from the results. 1. The water-cooled microstructure in which a specimen without the β phase was dissolved had a tessellated structure and the β phase did not precipitate during the solidification process. The β phase did not precipitate even during solution treatment at a high temperature, and the hardness decreased. However, in the case of air-cooling solidification, β phases precipitated in the solidification structure, and the hardness improved by solution treatment at a high temperature. 2. The solidified microstructure of the water-cooled alloy (the as-received specimen containing the β phase was dissolved) had a dendritic structure and the β phase was presented in the matrix. Therefore, at a dissolution temperature of 1323 K, the β phase did not melt or solidify into the matrix. Furthermore, the β phase did not melt and the hardness improved even after solution treatment at a high temperature was subsequently provided.
  • Titanium alloys with changeable Young's modulus for preventing stress shielding and springback
    M. Niinomi; M. Nakai; J. Hieda; X.L. Zhao; X.F. Zhao
    Ceramic Trans. 237 65 - 72 2012
  • Hakan Yilmazer; Mitsuo Niinomi; Toshikazu Akahori; Masaaki Nakai; Yoshikazu Todaka
    Int. J. Microstruct. Mater. Prop. Inderscience Publishers 7 (2-3) 168 - 186 1741-8410 2012 [Refereed]
  • H. Yilmazer; M. Niinomi; M. Nakai; J. Hieda; T. Akahori; Y. Todaka
    Key Eng. Mater. TRANS TECH PUBLICATIONS LTD 508 152 - 160 1013-9826 2012 [Refereed]
     
    Strengthening by grain refinement and increasing dislocation density through high-pressure torsion (HPT), which is an attractive technique to fabricate ultrafine grained and nanostructured metallic materials, is expected to provide beta-type Ti-29Nb-13Ta-4.6Zr (TNTZ) higher mechanical strength while maintaining low Young's modulus because they keep the original beta phase. However, the ductility shows reverse trend. Greater strength with enhanced ductility can be achieved by controlling precipitated phases through HPT processing after aging treatment. Aged TNTZ subjected to HPT processing at high N exhibits a homogeneous microstructure with ultrafine elongated grains having a high dislocation density and consequently non-equilibrium boundaries and distorted subgrains with non-uniform shapes and nanostructured intergranular precipitates of alpha phases. Therefore, the effect of HPT processing on the microstructure and mechanical hardness of TNTZ after aging treatment was systematically investigated in this study. TNTZ, which was subjected to aging treatment at 723 K for 259.2 ks in vacuum followed by water quenching, subjected to HPT processing at rotation numbers (N) of 1 to 20 under a pressure of around 1.25 GPa at room temperature. The microstructure of TNTZ(AT) consisted of precipitated needle-like omega phases in beta grains. However, TNTZ(AHPT) at N >= 10 comprises very fine alpha and small amount omega phases in ultrafine beta grains. Furthermore, the hardness of every TNTZ(AHPT) was totally much greater than that of TNTZ(AT). The hardness increased from the center to peripheral region of TNTZ(AHPT). In addition, the tensile strength of every TNTZ(AHPT) was greater than that of TNTZ(AT). The tensile strength of TNIZ(AHPT) increased, but the elongation decreased with increasing N and then both of them saturated at N >= 10.
  • Yonghwan Kim; Mitsuo Niinomi; Junko Hieda; Masaaki Nakai; Hisao Fukui
    Key Eng. Mater. TRANS TECH PUBLICATIONS LTD 508 166 - 171 1013-9826 2012 [Refereed]
     
    Change in the microstructure of the L1(0)-type ordered beta' phase precipitated in Ag-20Pd-12Au-14.5Cu alloy (mass%) subjected to solution treatment with varying solution treatment time was investigated. The size of the IT phase is found to decrease with increasing solution treatment time and the Vickers hardness of the alloy after solution treatment decreases. Experimental observations show that the microstructural change of the beta' phase strongly contributes to the change in Vickers hardness. In addition, the formation and growth of the beta' phase are concluded to be affected by the distribution of elements through solution treatment.
  • Yoon Seok Lee; Mitsuo Niinomi; Masaaki Nakai; Junko Hieda; Takashi Maeda; Yoshihisa Shirai; Ikuhiro Inagaki
    Key Eng. Mater. TRANS TECH PUBLICATIONS LTD 508 161 - 165 1013-9826 2012 [Refereed]
     
    In the present study, the effects of the microstructural morphologies of a Ti-6Al-4V (Ti-64) alloy on its fatigue behavior were investigated. Ti-64 bars were Subjected to two different thermo-mechanical processing methods. The first sample, referred to as Material-A, had a forged microstructure with the average primary alpha volume fraction of 44%. The second one, referred to as Material-B, had a hot-rolled microstructure with the average primary alpha volume fraction of 43%. Fatigue tests were performed on each sample to obtain S-N curves. The microstructure of each sample was observed using an optical microscopy in order to measure the grain sizes of the primary alpha and secondary alpha phases. The results of the fatigue tests indicated that Material-B demonstrates better fatigue strength than Material-A. The microstructure of the longitudinal section of each material was also observed to analyze the results of the fatigue tests. The measured diameters and volume fractions of the primary alpha phases of the two types of materials are similar. On the other hand, the secondary alpha width of each material is different. It is found that fatigue strength is related to the width of the secondary alpha phase.
  • X. F. Zhao; M. Niinomi; M. Nakai; J. Hieda
    MATERIALS INTEGRATION TRANS TECH PUBLICATIONS LTD 508 117 - 123 1013-9826 2012 
    Presently metallic rods that are used for spinal fixtures cannot meet the requirements of both surgeons and patients; surgeons require the material to have a high Young's modulus to suppress springback during the operation, whereas patients require the material to have a low Young's modulus to prevent the stress-shielding effect. In order to develop a novel biomedical titanium alloy with a changeable Young's modulus for spinal fixation applications via deformation-induced omega phase transformation. The effects of deformation-induced phases on the mechanical properties of metastable beta-type Ti-xCr alloys were investigated. The experimental results indicate that the Young's moduli, tensile strength, and Vickers hardness of the Ti-(10-12)Cr alloys increase remarkably by cold rolling. The results of the microstructural observations of Ti-12Cr alloys using a transmission electron microscopy (TEM) show that deformation-induced co phase transformation occurs during cold rolling. Therefore, the increase in Young's modulus of the alloys is attributed to the deformation-induced w phase, which is formed in the alloy during cold rolling at room temperature.
  • Masaaki Nakai; Mitsuo Niinomi; Xiaoli Zhao; Xingfeng Zhao
    Mater. Sci. Forum TRANS TECH PUBLICATIONS LTD 706-709 557 - 560 0255-5476 2012 [Refereed]
     
    A novel biomedical titanium alloy with the ability to undergo self adjustment in its Young's modulus was developed. In spinal fixation devices, the Young's modulus of the metallic implant rod should be sufficiently high to suppress springback for the surgeon, but should also be sufficiently low to prevent stress shielding for the patient. Therefore, deformation-induced omega phase transformation was introduced into beta-type titanium alloys so that the Young's modulus of only the deformed part would increase during operation, while that of the non-deformed part would remain low. The increase in the Young's modulus due to cold rolling was investigated for a binary Ti-12Cr alloy (mass%). Microstructural observation and Young's modulus measurement reveal that the Ti-12Cr alloy undergoes deformation-induced omega phase transformation and exhibits the increase in the Young's modulus by deformation.
  • Mitsuo Niinomi; Masaaki Nakai
    THERMEC 2011, PTS 1-4 TRANS TECH PUBLICATIONS LTD 706-709 135 - 142 0255-5476 2012 [Refereed]
     
    Oxygen enhances the strength of titanium alloys in general; however, excess oxygen can make titanium alloys brittle. On the other hand, oxygen enhances the precipitation of the alpha phase and suppresses the formation of the omega phase. Thus, using the optimal amount of oxygen is important to improve the mechanical properties of titanium alloys. The role of oxygen in titanium alloys is still not well understood. The effect of oxygen on the mechanical behavior of a beta-type titanium alloy, Ti-29Nb-13Ta-4.6Zr (referred to as TNTZ), which is used for biomedical applications, was investigated in this study. Oxygen was found to stabilize the omega phase in TNTZ. This behavior of oxygen is unusual considering the known behavior of oxygen in titanium alloys: oxygen is known to suppress the formation of the omega phase in titanium alloys. A small amount of oxygen increases the tensile strength but decreases the ductility of TNTZ. On the other hand, a large amount of oxygen, of around 0.7 mass%, increases both the tensile strength and the ductility of TNTZ. This phenomenon is unexpected.
  • Masaaki Nakai; Mitsuo Niinomi; Takahiro Oneda
    METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE SPRINGER 43A (1) 294 - 302 1073-5623 2012/01 [Refereed]
     
    The improvement in fatigue strength, with maintenance of a low Young's modulus, in a biomedical beta-type titanium alloy, Ti-29Nb-13Ta-4.6Zr (TNTZ), by thermomechanical treatment was investigated. A short aging time at an omega-phase-forming temperature combined with severe cold rolling was employed. A fine omega phase is observed in TNTZ subjected to this thermomechanical treatment. Because the rolling texture of beta phase is formed by cold rolling, such as the omega phase may be preferentially oriented to a direction that is effective for inhibiting the increase in Young's modulus. The samples aged at 573 K (300 A degrees C) for 3.6 ks and 10.8 ks after cold rolling exhibit a good balance between a high tensile strength and low Young's modulus. In the case of the sample aged for 3.6 ks, the tensile strength is improved, although the fatigue strength is not improved significantly. Both the tensile strength and the fatigue strength of the sample aged for 10.8 ks are improved. This fatigue strength is the highest among the TNTZ samples used in the current and in previous studies with Young's moduli less than 80 GPa.
  • 仲井正昭
    まてりあ,日本金属学会 The Japan Institute of Metals and Materials 51 (7) 309 - 312 1340-2625 2012
  • Xiaoli Zhao; Mitsuo Niinomi; Masaaki Nakai
    JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS ELSEVIER SCIENCE BV 4 (8) 2009 - 2016 1751-6161 2011/11 [Refereed]
     
    Nowadays, there is a significant research focus on the development of bio-implant materials that have not only a low Young's modulus but also other unique characteristics such as a changeable Young's modulus and the ability to prevent calcium phosphate formation. Taking advantage of deformation-induced phases is an effective way to obtain the changeable Young's modulus. This study investigated the relationship between the various deformation-induced products and the mechanical properties - including Young's modulus, microstructure, and tensile properties - of Ti-30Zr-(5,6,7)mass%Mo alloys subjected to solution treatment (ST) and cold-rolling (CR). After ST, each alloy is composed of a beta phase and a small amount of athermally formed omega phase, and exhibits a low Young's modulus. During CR, deformation-induced phase transformation occurs in all the alloys. The change in Young's modulus due to CR is highly dependent on the types of deformation-induced products. The decrease in Young's modulus due to CR is related to the deformation-induced alpha' phase transformation accompanying with the disappearance of athermal omega phase, and the increase in Young's modulus is attributed to the deformation-induced omega phase, which mainly exists in {332}(beta) mechanical twins. (C) 2011 Elsevier Ltd. All rights reserved.
  • Xiaoli Zhao; Mitsuo Niinomi; Masaaki Nakai; Takuya Ishimoto; Takayoshi Nakano
    MATERIALS SCIENCE & ENGINEERING C-MATERIALS FOR BIOLOGICAL APPLICATIONS ELSEVIER SCIENCE BV 31 (7) 1436 - 1444 0928-4931 2011/10 [Refereed]
     
    This research focuses on the development of new titanium (Ti) alloys with a low Young's modulus for use in removable implants. In this study. Ti-30Zr alloy was selected as the base alloy, and the effect of Mo addition on the microstructures, Young's moduli, and tensile properties of Ti-30Zr-(0-8 wt.% Mo) alloys was investigated in this study to assess the mechanical compatibility of these alloys for biomedical applications. Further, the cytocompatibility of a part of the designed alloys was examined. The experimental results indicate that both the microstructures and the mechanical properties of the designed alloys are strongly affected by the Mo contents. The Ti-30Zr-(6, 7 wt.%) Mo alloys, located near the boundary of (beta+omega)/beta with a metastable structure, show a good combination of a low Young's modulus, high tensile strength, fairly large elongation. In addition, Ti-30Zr-7Mo alloy is highly cytocompatible. (C) 2011 Elsevier B.V. All rights reserved.
  • Masaaki Nakai; Mitsuo Niinomi; Daisuke Ishii
    JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS ELSEVIER SCIENCE BV 4 (7) 1206 - 1218 1751-6161 2011/10 [Refereed]
     
    Porous titanium (pTi) can possess a low Young's modulus equal to that of human bone, depending on its porosity. However, the mechanical strength of pTi deteriorates greatly with increasing porosity. On the other hand, certain medical polymers exhibit biofunctionalities, which are not possessed intrinsically by metallic materials. Therefore, a biodegradable medical polymer, poly-L-lactic acid (PLLA), was used to fill in the pTi pores using a modified in-situ polymerization technique. The mechanical and biodegradable properties of pTi filled with PLLA (pTi/PLLA) as fabricated by this technique and the effects of the PLLA filling were evaluated in this study. The pTi pores are almost completely filled with PLLA by the developed process (i.e., technique). The tensile strength and tensile Young's modulus of pTi barely changes with the PLLA filling. However, the PLLA filling improves the compressive 0.2% proof stress of pTi having any porosity and increases the compressive Young's modulus of pTi having relatively high porosity. This difference between the tensile and compressive properties of pTi/PLLA is considered to be caused by the differing resistances of PLLA in the pores to tensile and compressive deformations. The PLLA filled into the pTi pores degrades during immersion in Hanks' solution at 310 K. The weight loss due to PLLA degradation increases with increasing immersion time. However, the rate of weight loss of pTi/PLLA during immersion decreases with increasing immersion time. Hydroxyapatite formation is observed on the surface of pTi/PLLA after immersion for >= 8 weeks. The decrease in the weight-loss rate may be caused by weight gain due to hydroxyapatite formation and/or the decrease in contact area with Hanks' solution caused by its formation on the surface of pTi/PLLA. (C) 2011 Elsevier Ltd. All rights reserved.
  • Qiang Li; Mitsuo Niinomi; Masaaki Nakai; Zhenduo Cui; Shengli Zhu; Xianjin Yang
    METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE SPRINGER 42A (9) 2843 - 2849 1073-5623 2011/09 [Refereed]
     
    The superelasticity and deformation behaviors of beta-type TiNb24Zr2 subjected to aging treatment were investigated in this study. As the aging time increased, the precipitation of isothermal omega phase was found to restrain the formations of twinning and stress-induced alpha aEuro(3) martensite. The superelastic recovery of the sample first improves and then deteriorates with extended aging times. A maximum and stable superelastic recovery of 4.3 pct is obtained for an aging time of 7.2 ks.
  • Xiaoli Zhao; Mitsuo Niinomi; Masaaki Nakai; Goro Miyamoto; Tadashi Furuhara
    ACTA BIOMATERIALIA ELSEVIER SCI LTD 7 (8) 3230 - 3236 1742-7061 2011/08 [Refereed]
     
    In order to develop a novel alloy with a changeable Young's modulus for spinal fixation applications, we investigated the microstructures, Young's moduli, and tensile properties of metastable Ti-30Zr-(Cr, Mo) alloys subjected to solution treatment (ST) and cold rolling (CR). All the alloys comprise a beta phase and small athermal omega phase, and they exhibit low Young's moduli after ST. During CR, deformation-induced phase transformation occurs in all the alloys. The change in Young's modulus after CR is highly dependent on the type of deformation-induced phase. The increase in Young's modulus after CR is attributed to the deformation-induced omega phase on {3 3 2} mechanical twinning. Ti-30Zr-3Cr-3Mo (3Cr3Mo), which exhibits excellent tensile properties and a changeable Young's modulus, shows a smaller springback than Ti-29Nb-13Ta-4.6Zr, a beta-type titanium alloy expected to be useful in spinal fixation applications. Thus, 3Cr3Mo is a potential candidate for spinal fixation applications. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
  • Toshikazu Akahori; Mitsuo Niinomi; Masaaki Nakai; Harumi Tsutsumi; Yusuke Kondo; Tomokazu Hattori; Hisao Fukui
    Journal of the Japan Institute of Metals and Materials 75 (8) 445 - 451 0021-4876 2011/08 [Refereed]
     
    The microstructures, mechanical properties, and biocompatibilities of as-solutionized Zr-Nb system alloys with different Nb contents for biomedical applications were investigated. The microstructures of Zr-5 mass%Nb, Zr-10 mass%Nb, and Zr-20 mass%Nb alloys subjected to solution treatment (ST) consist of a, α, ω and β phases while the microstructure of Zr-30 mass%Nb alloy subjected to ST consists of almost all single ß phase. Young's modulus of Zr-20 mass%Nb alloy shows the lowest value of 63 GPa among the others alloys although the tensile strength and 0.2% proof stress decrease because of decrease in volume fraction of m phase while Zr-10 mass%Nb alloy with a large amount of ω phase shows the highest values of Young's modulus, tensile strength, and 0.2% proof stress. The elongations of Zr-20 mass%Nb and Zr-30 mass%Nb alloys show relatively high values of 22% and 24%, respectively. The cell viability and bone-bonding characteristics of Zr-Nb system alloys are improved with increasing Nb content. Therefore, it is considered that Zr-Nb alloys have relatively high biocompatibility and belong to bio-inert metallic biomaterial. © 2011 The Japan Institute of Metals.
  • Toshikazu Akahori; Mitsuo Niinomi; Masaaki Nakai; Harumi Tsutsumi; Yusuke Kondo; Tomokazu Hattori; Hisao Fukui
    Journal of the Japan Institute of Metals and Materials JAPAN INST METALS 75 (8) 452 - 459 0021-4876 2011/08 [Refereed]
     
    The frictional wear characteristics, mechanical properties, and biocompatibilities of biomedical Zr-20 mass%Nb alloy (Zr-20Nb) subjected to solution treatment (ST) and air-oxidizing process (ACP) were investigated. Vickers hardness of the specimen surface of Zr-20Nb subjected to AOP at 973 K, 1073 K, and 1123 K are approximately 4.5 times larger than that of Zr-20Nb subjected to ST. Young's modulus of Zr-20Nb subjected to AOP increases with increasing AOP temperature up to 1073 K. 0.2% proof stress, tensile strength, and elongation of Zr-20Nb subjected to each AOP decrease proportionally with increasing AOP temperature, and is inferior to those of Zr-20Nb subjected to ST because of the growth of oxide layer with a large amount of micro-cracks and the diffusion of oxygen into the subsurface. Frictional wear loss of Zr-20Nb subjected to each AOP decreases drastically as compared to that of Zr-20Nb subjected to ST. Bone-compatibility of Zr-20Nb subjected to AOP at 973 K is better than that of AOP at 1073 K because of the existence of some cracks and partial exfoliation of oxide layer.
  • F. Geng; M. Niinomi; M. Nakai
    MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING ELSEVIER SCIENCE SA 528 (16-17) 5435 - 5445 0921-5093 2011/06 
    Plastic deformation behavior and its relation to tensile properties were investigated in an attractive beta-type titanium alloy (Ti-29Nb-13Ta-4.6Zr) with the oxygen content of 0.1-0.7 mass% subjected to hot rolling and solution treatment after hot rolling. Hereafter, Ti-29Nb-13Ta-4.6Zr is abbreviated to TNTZ. With the increase of oxygen content, the tensile strength and 0.2% proof stress of all the samples increase, however, their elongation indicates special change, which is contradictory to that reported conventionally. The elongation firstly decreases and then increases with the increase in the oxygen content. Therefore, TNTZ with high strength and high ductility due to the addition of high oxygen content (0.7 mass%) is obtained. Remarkable yielding phenomenon and strain hardening are observed in TNTZ, which can be explained by the interaction between oxygen atoms and a lot of screw and edge dislocations leading to the easy activation of the multiple slip systems. The deformation behavior changes with the addition of oxygen in TNTZ. The plastic deformation mode changes from the deformation-induced martensite transformation to slip mechanism. It is realized that there is a specific compositional area of oxygen in which the TNTZ exhibits strain hardening and high strength, and appropriate Young's modulus value. (C) 2011 Elsevier B.V. All rights reserved.
  • Xiu Song; Mitsuo Niinomi; Harumi Tsutsumi; Masaaki Nakai; Lei Wang
    MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING ELSEVIER SCIENCE SA 528 (16-17) 5600 - 5609 0921-5093 2011/06 [Refereed]
     
    TiB(2) was added to beta-type Ti-29Nb-13Ta-4.6Zr (TNTZ) to enhance its mechanical properties and lower its Young's modulus, and the microstructures and mechanical properties of TNTZ with 0.05-0.50 mass%B were investigated. The B concentration of TNTZ was controlled by varying the amount of added TiB(2) TNTZ with 0.05-0.50 mass%B consists of a beta-phase with a small amount ofTiB. As the B concentration increases, these TiB precipitates become increasingly efficient at preventing texture movement. The microstructure of TNTZ is refined by TiB, and the TNTZ grain size decreases as the B concentration increases. Moreover, the Young's moduli of TNTZ with 0.05-0.50 mass%B remain below 70 GPa, and are almost similar to that of TNTZ without TiB. The tensile strength of TNTZ with 0.05-0.50 mass%B is slightly improved, and the optimum tensile strength is enhanced by approximately 8%. TNTZ with 0.10 mass%B exhibits a good balance between tensile strength and the elongation. The results of this study are expected to contribute to the creation of a TNTZ-based material with improved mechanical properties and maintained Young's modulus that can be used as dental and orthopedic biomaterials. (C) 2011 Elsevier B.V. All rights reserved.
  • Kengo Narita; Mitsuo Niinomi; Masaaki Nakai; Kazuya Oribe
    JOURNAL OF THE JAPAN INSTITUTE OF METALS JAPAN INST METALS 75 (4) 198 - 206 0021-4876 2011/04 [Refereed]
     
    Microstructural evolution accompanying mechanical properties change by aging treatment at 723 K in cold-swaged Ti-29Nb-13Ta-4.6Zr were investigated in order to obtain an optimized aging condition for getting excellent mechanical properties. The precipitate free zone exists in Ti-29Nb-13Ta-4.6Zr after aging treatment for various time periods. Such the precipitate free zone corresponds to Nb and Ta-enriched region according to the result of element distribution analysis. With the increase in aging time, the area of the precipitate free zone decreases. Two types of alpha phase, acicular and ellipsoidal ones, are observed in Ti-29Nb-13Ta-4.6Zr after aging treatment for various time periods. The acicular alpha phase is precipitated in the Ti- and Zr-enriched region. While the size increases, the area fraction barely changes with aging time for acicular alpha phase, On the other hand, the ellipsoidal alpha phase precipitates at beta grain boundary and its subgrain boundary. Both the size and area fraction increase with the increase in aging time for the ellipsoidal alpha phase. The lattice correspondence between acicular alpha phase and beta matrix is [(1) over bar 10](beta)//[12 (1) over bar](alpha), (112)(beta)//((2) over bar 10)(alpha), and [(1) over bar 10]beta//[00 (1) over bar](alpha), (112)(beta)//(200)(alpha) until 86.4 ks of aging time. However, the lattice correspondence of [(1) over bar 10](beta)//[12 (1) over bar](alpha), (112)(beta)//((2) over bar 10)(alpha) disappear over 259.2 ks of aging time. Tensile strength of Ti-29Nb-13Ta-4.6Zr subjected to aging treatment after cold swaging is around 1200 GPa, regardless of aging time. On the other hand, elongation of those are decreased by the aging treatment up to 86.4 ks, increased at ones over 259.2 ks.
  • Masaaki Nakai; Mitsuo Niinomi; Xingfeng Zhao; Xiaoli Zhao
    MATERIALS LETTERS ELSEVIER SCIENCE BV 65 (4) 688 - 690 0167-577X 2011/02 [Refereed]
     
    In spinal fixation devices, the Young's modulus of the metallic implant rod should be not only sufficiently low to prevent stress shielding for the patient but also sufficiently high to suppress springback for the surgeon. This paper proposes a novel function of biomedical titanium alloys self-adjustment of Young's modulus. Deformation-induced omega phase transformation was introduced into beta-type titanium alloys so that the Young's modulus of only the deformed part would increase during operation, while that of the non-deformed part would remain low. The Young's modulus increase by deformation was investigated for a binary Ti-12Cr alloy. This alloy successfully underwent deformation-induced to phase transformation and exhibited the increase in the Young's modulus by deformation. (C) 2010 Elsevier B.V. All rights reserved.
  • Improvement of mechanical strength of a β-type titanium alloy for biomedical applications with keeping Young's modulus low by adding a small amount of TiB2 or Y2O3
    M. Niinomi; M. Nakai; X. Song; L. Wang
    Processing and Fabrication of Advanced Materials-XIX 817 - 827 2011
  • Development of new titanium-molybdenum alloys with changeable Young's modulus for spinal fixture devices
    X.F. Zhao; M. Niinomi; M. Nakai; J. Hieda
    Proc. ATEM'11 Article ID OS07F043  2011
  • Harumi Tsutsumi; Mitsuo Niinomi; Masaaki Nakai; Tatsuya Gozawa; Toshikazu Akahori; Kazumi Saito; Rong Tu; Takashi Goto
    Keikinzoku/Journal of Japan Institute of Light Metals 61 (1) 24 - 29 0451-5994 2011 
    A hydroxyapatite(HAp)film was fabricated on the surface of Ti-29Nb-13Ta-4.6Zr(TNTZ)using a metal-organic chemical vapor deposition(MOCVD)technique, and the mechanical biocompatibility and HAp formability of HApcoated TNTZ were evaluated and discussed in this study. HAp film is fabricated on the surface of TNTZ by controlling the heating temperature of the source bis-dipivaloylmethanatocalcium((Ca(dpm)2)and(C 6H5O)3PO). An α-phase precipitates in the TNTZ matrix after heating the substrate, and the mechanical properties and Young's modulus of HApcoated TNTZ are improved. HAp-coated TNTZ maintains excellent mechanical biocompatibility. The formability of HAp on HAp-coated TNTZ in Hank's balanced salt solution is better than that of HAp on non-coated TNTZ.
  • 新家光雄; 仲井正昭; 服部友一
    金属,アグネ技術センター 81 (5) 393 - 398 0368-6337 2011
  • Effect of TiB2 or Y2O3 additions on mechanical biofunctionality of Ti-29Nb-13Ta-4.6Zr for biomedical applications
    M. Niinomi; M. Nakai; S. Yonezawa; X. Song; L. Wang
    Ceramic Trans. 228 75 - 81 2011
  • Toshikazu Akahori; Mitsuo Niinomi; Masaaki Nakai; Harumi Tsutsumi; Shiro Aki; Yoshio Itsumi; Shogo Murakami; Hideto Oyama
    Keikinzoku/Journal of Japan Institute of Light Metals 61 (12) 711 - 717 0451-5994 2011 
    The effects of microstructures on the mechanical properties of Ti-4.5Al-2Mo-1.6V-0.5Fe-0.3Si-0.03C(KS Ti-9)were systematically investigated by conducting several heat treatments for next-generation aircraft applications. The mechanical strength of as-received KS Ti-9 exhibits high anisotropy that is derived from the intense texture(T-texture)of the primary α phase. Such high anisotropy is observed in KS Ti-9 annealed at temperatures slightly below β -transus, but it is drastically decreased in KS Ti-9 subjected to an anisotropy controlling treatment. The reduction in the anisotropy for KS Ti-9 is related to the differences in the orientations of the precipitated acicular α phase.
  • Toshikazu Akahori; Mitsuo Niinomi; Masaaki Nakai; Harumi Tsutsumi; Shiro Aki; Yoshio Itsumi; Shogo Murakami; Hideto Oyama
    Keikinzoku/Journal of Japan Institute of Light Metals 61 (12) 705 - 710 0451-5994 2011 
    The relationship between microstructures and mechanical properties such as tensile and fatigue properties were systematically investigated by conducting several heat treatments on Ti-4.5Al-4Cr-0.5Fe-0.2C(KS EL-F)and Ti-4.5Al-2Cr-1Fe-0.1(KS EL-F mod)for next-generation aircraft applications. TiC and TiCr2 are formed in KS EL-F and KS EL-F mod annealed at temperatures higher than β -transus and aged at 773 K, respectively. However, the precipitation trends of TiC and TiCr2 are considerably higher in the case of KS EL-F because the amounts of both these precipitates are drastically suppressed in KS EL-F mod even when the heat treatments are identical. As-received KS EL-F and KS EL-Fmod exhibit excellent fatigue strength as compared with annealed Ti-6Al-4V. Although the presence of TiCr2 tends to decrease the fatigue strength, the aged KS EL-F mod exhibits higher fatigue strength than the as-received KS EL-F mod with very low TiCr 2 amounts. Therefore, the aging treatment for KS EL-F mod can be effective in improving the fatigue strength.
  • 椙村豊彦; 福井壽男; 甲斐川健太郎; 新家光雄; 赤堀俊和; 仲井正昭; 稗田純子
    日本歯科理工学会誌 The Japanese Society for Dental Materials and Devices 30 (6) 410 - 417 1884-4421 2011 
    The purpose of this study was to investigate how the presence or absence of a β-phase in the solidification structure of commercial dental casting Au-Ag-Pd alloys affects the hardness of such alloys when solution-treated at a temperature of 1,123K. Samples with the β-phase in its solidification structure were fabricated by conventional centrifugal casting, while samples without the β-phase were fabricated by liquid rapid solidification (LRS). The solution-treated centrifugal-cast samples showed both α-and β-phases on XRD and a β'-phase on TEM images. The solution-treated LRS samples, on the other hand, showed an α-phase and a minimal α2-phase on XRD and a single α-phase on TEM images. The β-phase present in the solidification structure promoted the ordering process of the L10-type β'-phase on subsequent heat treatment, thereby improving the hardness. In addition, aging treatment at a temperature of 673K improved the hardness through β-phase and β'-phase precipitations regardless of whether the β-phase was present in the solidification structure. The results of this experiment show that solution heat treatment at 1,123K only improves the hardness when the β-phase is present in the solidification structure.
  • M. Niinomi; M. Nakai
    International Journal of Biomaterials 2011 Article ID 836587  1687-8787 2011 
    β-type titanium alloys with low Young's modulus are required to inhibit bone atrophy and enhance bone remodeling for implants used to substitute failed hard tissue. At the same time, these titanium alloys are required to have high static and dynamic strength. On the other hand, metallic biomaterials with variable Young's modulus are required to satisfy the needs of both patients and surgeons, namely, low and high Young's moduli, respectively. In this paper, we have discussed effective methods to improve the static and dynamic strength while maintaining low Young's modulus for β-type titanium alloys used in biomedical applications. Then, the advantage of low Young's modulus of β-type titanium alloys in biomedical applications has been discussed from the perspective of inhibiting bone atrophy and enhancing bone remodeling. Further, we have discussed the development of β-type titanium alloys with a self-adjusting Young's modulus for use in removable implants. © 2011 M. Niinomi and M. Nakai.
  • Harumi Tsutsumi; Mitsuo Niinomi; Masaaki Nakai; Tatsuya Gozawa; Toshikazu Akahoril; Kazumi Saito; Rong Tu; Takashi Goto
    MATERIALS TRANSACTIONS JAPAN INST METALS 51 (12) 2277 - 2283 1345-9678 2010/12 [Refereed]
     
    A hydroxyapatite (HAp) film was fabricated on the surface of Ti-29Nb-13Ta-4.6Zr (TNTZ) using a metal-organic chemical vapor deposition (MOCVD) technique, and the mechanical biocompatibility and HAp formability of HAp-coated TNTZ were evaluated and discussed in this study. HAp film is fabricated on the surface of TNTZ by controlling the heating temperature of the source (bis-dipivaloylmethanatocalcium (Ca(dpm)(2)) and (C6H5O)(3)PO). An alpha-phase precipitates in the TNTZ matrix after heating the substrate, and the mechanical properties and Young's modulus of HAp-coated TNTZ are improved. HAp-coated TNTZ maintains excellent mechanical biocompatibility. The formability of HAp on HAp-coated TNTZ in Hank's balanced salt solution is better than that of HAp on non-coated TNTZ. [doi:10.2320/matertrans.L-M2010821]
  • Toshikazu Akahori; Mitsuo Niinomi; Masaaki Nakai; Harumi Tsutsumi; Toru Kanno; Yong-Hwan Kim; Hisao Fukui
    Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals 74 (6) 337 - 344 0021-4876 2010/06 
    The purpose in this study is to investigate the effect of microstructure on the unique hardening behavior of dental silver alloy, Ag-20Pd-14.5Cu-12Au (mass%), fabricated by hot rolling process (AS material), which is in as-received condition, and liquid rapid solidification (LRS) process (LRS material). The following results were obtained. The microstructure of AS material is consisted of α1, α, and β phases. The microstructure of AS material changes to α, β, and β' phases through a solution treatment (ST). The microstructure of LRS material is consisted of α, α1, and α2 phases without β phase. The microstructure of LRS material becomes single α phase through ST. Relatively large β phases with the diameter of tens of μm on AS material coarsen according to increasing the ST time, while the small those with the diameter of a few μm are solid-soluted into the matrix. On the other hand, the coherent participation of β' phases with long and short axes of around 100 nm and 10 nm, respectively, also occurs during ST although the amount of β' phase decreases with increasing the ST time. The hard-ness and tensile strength of LRS material and LRS material subjected to ST are relatively smaller than those of AS material and AS material subjected to the same treatment. From this results, the effect of solid solution hardening of α, α1 and α2 phases is lower than that of precipitation hardening of β' phases. In a case of the unique hardening seems to occur because the precipitation of β' phases are enhanced during ST. © 2010 The Japan Institute of Metals.
  • Harumi Tsutsumi; Mitsuo Niinomi; Toshikazu Akahori; Masaaki Nakai; Tsutomu Takeuchi; Shigeki Katsura
    Keikinzoku/Journal of Japan Institute of Light Metals 60 (4) 170 - 176 0451-5994 2010/04 
    The applicability of a calcia mold to casting a β-type titanium alloy, Ti-29Nb-13Ta-4.6Zr (TNTZ), was evaluated with focusing on the dimensional accuracy of the casting in this study. Pure zirconium particles were added to a calcia mold to take advantage of the expansion of oxidized zirconium during the baking process in order to compensate for the solidification shrinkage of TNTZ. The morphological characteristics of the casting surface, such as the roughness and dimensional accuracy, of the cast TNTZ were investigated. The dilation ratio of the calcia mold is found to increase with increasing the number of pure zirconium particles. The addition of 12 mass % or 14 mass % pure zirconium particles compensates for not only the solidification of TNTZ but also the occurrence of shrinkage of the calcia mold. In addition, the formation of a surface reaction layer in TNTZ is restrained to a larger extent by casting into a calcia mold than into a magnesia mold, which is the conventional investment mold for titanium casting. Furthermore, the volume fraction and number of casting defects are also restrained to a larger extent by casting into a calcia mold than into a magnesia mold. The results of this study should lead to enhancements in the creation of cast TNTZ for dental products.
  • Harumi Tsutsumi; Mitsuo Niinomi; Toshikazu Akahori; Masaaki Nakai; Tsutomu Takeuchi; Shigeki Katsura
    Keikinzoku/Journal of Japan Institute of Light Metals 60 (4) 177 - 182 0451-5994 2010/04 
    A calcia mold, which is stable at high temperatures for dental precision casting of β-type titanium alloys such as Ti-29mass%Nb-13mass%Ta-4.6mass%Zr alloy (TNTZ) with high melting point, has been developed. The applicability of the calcia mold to casting TNTZ was evaluated with focusing on the mechanical properties of the casting in this study. The molten TNTZ was cast into the calcia mold of which dimensional accuracy was controlled by adding pure zirconium particles. The tensile and fatigue properties of TNTZ cast into the calcia mold were examined with comparing those of TNTZ cast into the magnesia mold, which is the conventional one for casting titanium alloys. The tensile properties of TNTZ cast into the calcia and the magnesia molds are not markedly different The fatigue strength of TNTZ cast into the calcia mold in the low- and high-cycle fatigue life regions is slightly higher than that of TNTZ cast into the magnesia mold. Therefore, the calcia mold is expected to be applicable to the dental precision casting of TNTZ.
  • Improvement in fatigue strength of Ti-29Nb-13Ta-4.6Zr alloy while maintaining low modulus for biomedical applications
    M. Nakai; M. Niinomi; T. Akahori; H. Tsutsumi; T. Oneda; M. Ogawa
    Medical Device Materials V 86 - 89 2010
  • Recent development of high mechanical bio-functional metallic biomaterial
    M. Niinomi; M. Nakai
    Proc. 15th International Metallurgy and Materials Congress (IMMC2010) 561 - 569 2010
  • Effect of high-pressure torsion processing on microstructure and mechanical properties of a biomedical β-type titanium alloy
    H. Yilmazer; M. Niinomi; T. Akahori; M. Nakai; Y. Todaka
    Proc. 15th International Metallurgy and Materials Congress (IMMC2010) 570 - 579 2010
  • Mitsuo Niinomi; Masaaki Nakai; Toshikazu Akahori; Harumi Tsutsumi
    Mater. Sci. Forum TRANS TECH PUBLICATIONS LTD 638-642 16 - 21 0255-5476 2010 [Refereed]
     
    Negative thermal expansion, i.e. a type of shrinkage that occurs during heating, was observed in cold-rolled Ti-29Nb-13Ta-4.6Zr alloy (mass%) (TNTZ). The reduction ratio of cold rolling was systematically changed, and then the thermal expansion rate was measured using a dilatometer. The cyclicity of thermal expansion was also examined for the cold-rolled TNTZ. Further, the effect of oxygen content on the thermal expansion behavior of the cold rolled TNTZ was examined. With an increase in the reduction ratio of cold rolling, the thermal expansion rate of TNTZ cold-rolled parallel to the rolling direction (RD) decreases, but it increases in TNTZ cold-rolled parallel to the transverse direction (TD). The cyclicity of above-mentioned anomalous thermal expansion is observed in a temperature range below 473 K, but it is not observed when the specimen is heated to above 573 K in the first cycle. The oxygen suppresses the negative thermal expansion behavior of TNTZ.
  • Toshikazu Akahori; Mitsuo Niinomi; Masaaki Nakai; Harumi Tsutsumi; Tomokazu Hattori; Hisao Fukui
    Materials Science Forum 638-642 495 - 500 0255-5476 2010 [Refereed]
     
    A new β-type Ti alloy composed of non-toxic and allergy-free elements like Nb, Ta, and Zr, Ti-29Nb-13Ta-4.6Zr alloy (TNTZ) proposed by present authors, has been developed in order to achieve relatively low Young's modulus and excellent mechanical performance. On the other hand, Zr has been also paid attention as metallic biomaterial for the next generation because of good biocompatibility nearly equal to Ti or a few GPa smaller Young's modulus as compared to one. In this study, mechanical performances such as tensile properties and Young's modulus of TNTZ subjected to thermo-mechanical treatments or severe deformation, and the mechanical properties and biocompatibility of Zr-Nb system alloys were investigated in order to judge their potential for biomedical applications. Young's modulus of as-solutionized TNTZ, which is around 63 GPa, is pretty similar to that of as-cold-rolled TNTZ. The Young's moduli of hot-rolled Ti-6Al-4V ELI alloy are respective around 110 GPa. The Young's moduli of as-solutionized and as-cold-rolled TNTZ are around a half of those, and are twice as large as that of the cortical bone. The tensile strengths of TNTZ aged after solution treatment and those aged after cold rolling decrease with an increase in the aging temperature, although the elongation shows the reverse trend. The tensile strength of as-cold-rolled TNTZ is improved drastically through severe deformation such as high pressure torsion and shows more than 1000 MPa. Zr-XNb system alloy (X: 5-30mass%) shows the smallest value of Young's modulus (around 58 GPa) at Nb content of 20mass%. In the case of implantation of the bars made of Zr-XNb system alloys into the lateral femoral condyles of Japanese white rabbits, the tendency of contact between the cancellous bone and the bar becomes remarkably at 24 weeks after the implantation according to increasing with Nb content. © (2010) Trans Tech Publications.
  • Kengo Narita; Mitsuo Niinomi; Masaaki Nakai; Toshikazu Akahori; Harumi Tsutsumi; Kazuya Oribe
    Adv. Mater. Res. TRANS TECH PUBLICATIONS LTD 89-91 400 - 404 1022-6680 2010 [Refereed]
     
    Implanting a spinal fixture using metallic rods is one of the effective treatments for spinal diseases. Because cyclic bending stress is loaded on the implant rods when patients move their upper bodies in daily life, bending fatigue properties are important for the implant rod. Further, the implant rods are bended plastically into a curved shape of spine by hand in a surgical operation. In that case, keeping shape is important, namely bending spring back properties are important factors. On the other hand, a biomedical beta-type titanium alloy, Ti-29Nb-13Ta-4.6Zr (mass %) alloy (TNTZ), has been developed by the authors. Currently, this alloy are investigated to be applied to the above mentioned implant rod practically. Therefore, four-point bending fatigue and three point-bending spring back properties of TNTZ subjected various heat treatments were examined in this study. TNTZ rods were subjected to solution treatment, and then some of them were subjected to aging treatment at 673 K or 723 K for 259.2 ks, followed by water quenching. Then, four-point bending fatigue and three-point bending spring back tests were carried out on TNTZ rods subjected to the various heat treatments mentioned above. The bending fatigue strength at 2.5 million cycles in the high cycle fatigue region are not much different among any TNTZ rod. However, the bending fatigue strength of the Ti-6Al-4V ELI (Ti64) rod exceeds the fatigue strengths of every TNTZ rods in both low and high cycle fatigue regions. On the other hand, the lower spring back, which is a favorable property, was obtained for some TNTZ rod than Ti64 rod.
  • Harumi Tsutsumi; Mitsuo Niinomi; Toshikazu Akahori; Masaaki Nakai; Tsutomu Takeuchi; Shigeki Katsura
    MATERIALS TRANSACTIONS JAPAN INST METALS 51 (1) 128 - 135 1345-9678 2010/01 [Refereed]
     
    The applicability of a calcia mold to casting a beta-type titanium alloy, Ti-29Nb-13Ta-4.6Zr (TNTZ). was evaluated with focusing on the dimensional accuracy of the casting ill this study. Pure zirconium particles were added to a calcia mold to take advantage of the expansion of oxidized zirconium during the baking process in order to compensate for the solidification shrinkage of TNTZ. The morphological characteristics of the casting surface. such as the roughness and dimensional accuracy. of the cast TNTZ were investigated. The dilation ratio of the calcia mold is found to met ease with increasing the number of pure zirconium particles. The addition of 12 mass% or 14 mass% pure zirconium particles compensates for not only the solidification of TNTZ but also the occurrence of shrinkage of the calcia mold. In additions the formation of a surface reaction layer in TNTZ is restrained to a larger extent by casting into a calcia mold than into a magnesia mold, which is the conventional investment mold for titanium casting. Furthermore, the volume fraction and number of casting defects are also restrained to a larger extent by casting into a calcia mold that into a magnesia mold. The results Of this study should lead to enhancements in the creation of cast TNTZ for dental products. [doi:10.2320/matertrans.L-M2009827]
  • Harumi Tsutsumi; Mitsuo Niinomi; Toshikazu Akahori; Masaaki Nakai; Tsutomu Takeuchi; Shigeki Katsura
    MATERIALS TRANSACTIONS JAPAN INST METALS 51 (1) 136 - 142 1345-9678 2010/01 [Refereed]
     
    A calcia mold which is stable at high temperatures for dental precision casting of beta-type titanium alloys such as Ti-29Nb-13Ta-4.6Zr (TNTZ) with high inching point, has been developed. The applicability of the calcia mold to casting TNTZ was evaluated with focusing oil the mechanical properties of the casting in this study. The molten TNTZ was cast into the calcia mold of which dimensional accuracy was controlled by adding pure zirconium particles. The tensile and fatigue properties of TNTZ cast into the calcia mold were examined with comparing those of TNTZ cast into the magnesia mold, which is the conventional one for casting titanium alloys. The tensile properties of TNTZ cast into the calcia and the magnesia molds are not markedly different. The fatigue strength of TNTZ cast into the calcia mold in the low- and high-cycle fatigue life regions is slightly higher than that of TNTZ cast into the magnesia mold. Therefore, the calcia mold is expected to he applicable to the dental precision casting, of TNTZ. [doi:10.2320/matertrans.L-M2009828]
  • 赤堀俊和; 新家光雄; 小野智之; 仲井正昭; 堤晴美
    鉄と鋼 The Iron and Steel Institute of Japan 96 (2) 93 - 100 0021-1575 2010 
    Ti–30Nb–10Ta–5Zr–0.3O (TNTZO) alloy, which is simplified chemical composition similar to that of biomedical Ti–29Nb–13Ta–4.6Zr alloy, and the same system alloys of TNTZO with different oxygen (O) and niobium (Nb) contents such as Ti–30Nb–10Ta–5Zr–0.5O, Ti–30Nb–10Ta–5Zr–0.6O alloys, and Ti–27Nb–10Ta–5Zr–0.3O, Ti–28Nb–10Ta–5Zr–0.3O and Ti–29Nb–10Ta–5Zr–0.3O alloys are fabricated by powder metallurgy processing, in which it undergoes severe deformation during swaging. Changes in the deformation behaviors of these alloys caused by small changes in the O and Nb contents are investigated in this study. The stress–strain curve of TNTZO changes nonlinearly with the strain and is characterized by a small stress hysteresis, indicating that TNTZO shows a nonlinear recovery behavior during unloading. This deformation in the alloy is a result of a typical elastic deformation as well as stress-induced martensitic transformation. However, with an increase in the O content, as in the case of alloys with 0.5O and 0.6O, the stress–strain curves change almost linearly with the strain and exhibit a linear recovery behavior during unloading without stress hysteresis. In such alloys, deformation is mainly caused by the typical elastic deformation. On the other hand, with a decrease in the Nb content, the stress–strain curves show two steps with an increase in the strain, and deformation is accompanied by stress hysteresis during both loading and unloading. This deformation is mainly caused by stress-induced martensitic transformation and reverse transformation.
  • Mitsuo Niinomi; Kengo Narita; Masaaki Nakai; Toshikazu Akahori; Harumi Tsutsumi; Kazuya Oribe
    Mater. Sci. Forum TRANS TECH PUBLICATIONS LTD 654-656 2142 - 2145 0255-5476 2010 
    Mechanical properties of beta-type biomedical Ti-29Nb-13Ta-4.6Zr (mass %) (TNTZ), which exhibits non-toxicity and a low modulus similar to that of cortical bone, is improved by thermomechanical treatments, including severe cold swaging. Simultaneously, the biocompatibility of a TNTZ spinal implant rod with living tissue is evaluated using ovines, and TNTZ is proved to show good biocompatibility with bovine tissue.
  • Masaaki Nakai; Mitsuo Niinomi; Toshikazu Akahori; Harumi Tsutsumi
    Mater. Sci. Forum TRANS TECH PUBLICATIONS LTD 654-656 2134 - 2137 0255-5476 2010 [Refereed]
     
    A peculiar effect of oxygen on co-phase stability, i.e., the enhancement of the isothermal co-phase formation during aging due to oxygen addition was observed in the Ti-29Nb-13Ta-4.6Zr; this effect is contradictory to that reported conventionally. The effect was analyzed from the viewpoint of distribution of alloying elements. Oxygen and/or zirconium may dissolve in the omega phase during aging, resulting in the stabilization of the omega phase in this alloy.
  • Xiu Song; Mitsuo Niinomi; Harumi Tsutsumi; Toshikazu Akahori; Masaaki Nakai; Satoshi Yonezawa; Lei Wang
    Mater. Sci. Forum TRANS TECH PUBLICATIONS LTD 654-656 2138 - 2141 0255-5476 2010 [Refereed]
     
    Y2O3 was added to beta-type Ti-29Nb-13Ta-4.6Zr (TNTZ) in order to achieve excellent mechanical performance and low Young's modulus. TNTZ specimens with 0.05%-1.0% Y are all found to be composed of a beta phase. Young's moduli of TNTZ with 0.05-1.0% Y are all maintained low, and are almost the same as that of TNTZ without Y2O3. The grain size of TNTZ with 0.05%-1.0% Y is smaller than that of TNTZ without Y2O3. Moreover, Y2O3 precipitates can prevent the texture movement, and this effect becomes more obvious with an increase in the Y concentration. The tensile strength of TNTZ is successfully improved by adding Y2O3. TNTZ specimens with 0.2% and 1.0% Y exhibit good balance between the tensile strength and the elongation.
  • Yonghwan Kim; Mituo Niinomi; Toshikazu Akahori; Masaaki Nakai; Harumi Tsutsum; Hisao Fukui
    Mater. Sci. Forum TRANS TECH PUBLICATIONS LTD 654-656 2200 - 2203 0255-5476 2010 
    Hardness of Ag-20Pd-12Au-14.5Cu (mass%) subjected to a solution treatment (ST) at a temperature over 1073 K followed by water quenching increases drastically. This unique hardening behavior is not clarified becasue of their complex microsturucures. In this study, the relationship between the unique hardening behaviour and the microstructure of dental Ag-20Pd-12Au-xCu subjected to ST with different Cu/Ag ratios was investigated. The Vickers hardness of Ag-20Pd-12Au-14.5Cu increases remarkably from 192 to 286 Hv after ST whereas that of Ag-20Pd-12Au-6.5Cu decreases and that of Ag-20Pd-12Au-20Cu increases slightly after ST, respectively. The spotty regions are observed in only certain areas of Ag-20Pd-12Au-14.5Cu subject to ST. It is considered that the appearance of the spotty regions affects mainly to the unique hardening behaviour in Ag-20Pd-12Au-xCu.
  • Mitsuo Niinomi; Masaaki Nakai; Toshikazu Akahori; Harumi Tsutsumi
    Key Eng. Mater. TRANS TECH PUBLICATIONS LTD 436 179 - 184 1013-9826 2010 [Refereed]
     
    Oxygen plays very important roles in titanium and its alloys. Solute oxygen in titanium alloys leads to solid solution strengthening, suppressing the precipitation of the athermal omega or orthorhombic martensite phase, enhancing the formation of the alpha-case, etc. The proper using oxygen is effective to improve the mechanical functionalities of titanium alloys. However, the role of oxygen in titanium alloys is still not well understood. Therefore, the effect of oxygen on the mechanical functionalities such as strength-ductility balance, hardness, and Young's modulus in Ti-29nb-13Ta-4.6Zr was investigated.
  • blast-induced traumatic brain injury（bTBI）：multidisciplinary teamによる病態解明から機器開発まで
    中川敦寛; 荒船龍彦; 大谷清伸; 山本裕朗; 松永忠雄; 鷲尾利克; 塚本哲; 中野徹; 仲井正昭; 合田圭介; 小川欣一; 孫明宇; 隈部俊宏; 芳賀洋一; Bahram Jalali; 牛田多加志; 高山和喜; 西野精治; 新家光雄; 佐久間一郎; 冨永悌二
    神経外傷 33 (2) 187 - 194 2010
  • Masaaki Nakai; Mitsuo Niinomi; Toshikazu Akahori; Harumi Tsutsumi; Shinichi Itsuno; Naoki Haraguchi; Yoshinori Itoh; Tadashi Ogasawara; Takashi Onishi; Taku Shindoh
    JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS ELSEVIER SCIENCE BV 3 (1) 41 - 50 1751-6161 2010/01 [Refereed]
     
    Porous metallic materials can have a low Young's modulus, which is approximately equal to that of human bone, by controlling the porosity. On the other hand, certain medical polymers exhibit biofunctionalities that are not intrinsically present in metallic materials. Therefore, a composite consisting of these materials is expected to possess both these advantages for biomedical applications. However, in the case of using porous metallic materials, the deterioration of mechanical properties should of concern because a stress concentration may be induced near the pores.In this study, for the fabrication of the abovementioned composite, a versatile process for filling a medical polymer into a porous metallic material has been developed using porous pure titanium (pTi) and polymethylmethacrylate (PMMA). Then, the tensile strength and Young's modulus of pTi filled with PMMA (pTi/PMMA) fabricated using this process are systematically investigated.The tensile strength of pTi can be improved by the PMMA filling, Particularly, the improvement in the tensile strength of pTi pretreated using a silane coupling agent before PMMA filling is greater than that of the non-pretreated pTi because the stress concentration near the pores may be reduced by the improvement in the interfacial adhesiveness between the titanium particles and the PMMA. in contrast, the effect of the PMMA filling on the Young's modulus of pTi is smaller than that on the tensile strength because the Young's modulus of PMMA is considerably lower than that of pTi. Further, tensile strengths and Young's moduli comparable to the tensile strength and Young's modulus of the human bone are successfully obtained in the case of some pTi/PMMA samples. (C) 2009 Elsevier Ltd. All rights reserved.
  • 仲井正昭
    まてりあ,日本金属学会 The Japan Institute of Metals and Materials 49 (9) 437 - 440 1340-2625 2010
  • Masaaki Nakai; Mitsuo Niinomi; Toshikazu Akahori; Harumi Tsutsumi; Michiharu Ogawa
    MATERIALS TRANSACTIONS JAPAN INST METALS 50 (12) 2716 - 2720 1345-9678 2009/12 [Refereed]
     
    The effect of oxygen content on the microstructure and mechanical properties of the Ti-29 mass%Nb-13 mass%Ta-4.6 mass%Zr (TNTZ) alloy was investigated in this study. The microstructural observation of TNTZ alloys, containing 0.1-0.4 mass% oxygen, subjected to solution treatment shows the presence of a single phase. With an increase in oxygen content, the hardness, tensile strength, and Young's modulus of TNTZ alloy increase, but its elongation decreases. Further, the a phase precipitates in TNTZ alloys subjected to aging treatment at 723 K for 259.2 ks. The results of transmission electron microscopy and X-ray diffraction analysis indicate that the size and volume fraction of the a phase increase with oxygen content. Corresponding to the changes in the microstructure. the mechanical properties of TNTZ alloy subjected to aging treatment at 723 K change with oxygen content. The increase in oxygen content leads to enhancement of the age hardening of TNTZ alloy, thereby increasing both tensile strength and Young's modulus of TNTZ alloy, but its elongation decreases due to the a-phase precipitation. The mechanical properties of TNTZ alloy (Young's modulus: around 60-100 GPa, tensile strength: around 600-1400 MPa, and elongation: around 5-25%) vary significantly depending on oxygen content and heat treatment. [doi: 10.2320/matertrans.MA200904]
  • Harumi Tsutsumi; Mitsuo Niinomi; Toshikazu Akahori; Masaaki Nakai; Tsutomu Takeuchi; Shigeki Katsura
    MATERIALS TRANSACTIONS JAPAN INST METALS 50 (8) 2057 - 2063 1345-9678 2009/08 [Refereed]
     
    The objective of this study is to develop a dental precision casting process for a beta-type titanium alloy, Ti-29Nb-13Ta-4.6Zr (TNTZ) alloy which has been developed for biomedical applications, using a mold made by electrically fused calcia particles. The effect of a combination of different sizes of calcia particles on the surface condition of the mold was investigated. In addition, to obtain a smooth surface, a cast TNTZ was made using a mold made using a mixture of calcia particles with a wax pattern conducted with calcia Slurry coatings. Furthermore, surface reaction layer of the cast TNTZ was evaluated using an optical microscopy. a Vickers' hardness test and a X-ray diffractometry. The surface of the mold fabricated with a mixture of fine (diameter < 0.3 mm) and coarse (diameter = 1-3 mm) calcia particles is smooth and showed no cracks or defects. In addition, the Surfaces of the cast TNTZ made using the duplex-coated wax pattern with the fine pure calcia slurry and crushed silica fiber-rein forced fine calcia slurry are very line. Furthermore, the formation of the surface reaction layer on the cast TNTZ is remarkably inhibited. The results of this study should lead to enhancements in the creation of cast TNTZ for dental products. [doi: 10.2320/matertrans.M2009139]
  • M. Niinomi; T. Akahori; M. Nakai; H. Tsutsumi
    MATERIALS TRANSACTIONS JAPAN INST METALS 50 (7) 1704 - 1712 1345-9678 2009/07 
    There is a possibility for beta-type Ti-29Nb-13Ta-4.6Zr(TNTZ) to exhibit super-elastic characteristics, which is advantageous for biomedical applications such as orthodontic wires. Thermomechanical treatments are expected to induce super-elastic characteristics in beta-type titanium alloys. Therefore, TNTZ specimens were subjected to various thermomechanical treatments, including solution treatments and severe cold rolling, wherein the second solution treatment temperature, second solution treatment time, and reduction ratio of cold rolling were varied in order to investigate the elastic deformation characteristics. One of the thermomechanical treatments induces super-elastic characteristics in a TNTZ specimen. In particular, a highest total pseudoelastic strain of 2.8% is measured in the TNTZ specimen subjected to the thermomechanical treatment at a cold rolling reduction ratio of 95%, second solution treatment temperature of 1073 K, and second solution treatment time of 0.3 ks. Tensile loading and unloading stress-strain curves of the TNTZ specimens subjected to various thermomechanical treatments indicate a high total pseudoelastic strain and exhibit three step deformation process. An alpha '' martensite phase is formed in the TNTZ specimen subjected to the thermomechanical treatment carried out under the above mentioned conditions. [doi:10.2320/matertrans.MF200922]
  • Masaaki Nakai; Mitsuo Niinomi; Toshikazu Akahori; Harumi Tsutsumi; Xiaoliang Feng; Michiharu Ogawa
    MATERIALS TRANSACTIONS JAPAN INST METALS 50 (2) 423 - 426 1345-9678 2009/02 [Refereed]
     
    Negative thermal expansion, i.e. a type of shrinkage that occurs during heating, was observed in cold-rolled Ti-29Nb-13Ta-4.6Zr alloy (mass%) (TNTZ). The reduction ratio of cold rolling and the angle of the longitudinal axis of specimens with respect to the cold-rolling direction were systematically changed, and then the thermal expansion rate was measured using a dilatometer. Further, the cyclicity of thermal expansion was examined for the cold-rolled TNTZ. From the results, it is observed that with an increase in the reduction ratio of cold rolling, the thermal expansion rate of TNTZ cold-rolled parallel to the rolling direction (RD) decreases, but it increases in TNTZ cold-rolled parallel to the transverse direction (TD). With regard to the anisotropy of thermal expansion, the thermal expansion rate increases with the angle between the longitudinal axis of the specimens and RD. Further, the cyclicity of the above-mentioned anomalous thermal expansion is observed in a temperature range below 473 K, but it is not observed when the specimen is heated above 573 K in the first cycle. [doi: 10.2320/matertrans.MRP2008380]
  • Medical polymer filling into porous titanium fabricated by powder metallurgy and its mechanical functionality
    Mitsuo Niinomi; Masaaki Nakai; Toshikazu Akahori; Harumi Tsutsumi; Shinichi Itsuno; Naoki Haraguchi; Yoshinori Itoh; Tadashi Ogasawara; Takashi Onishi; Taku Shindoh
    Euro PM2009 Proceedings: PM Biomaterials 2009
  • Towards developing ubiquitous titanium alloys
    M. Niinomi; T. Akahori; M. Nakai; H. Tsutsumi
    Processing and fabrication of advanced materials-XVIII 2 645 - 665 2009
  • Improvement in fatigue strength of Ti-29Nb-13Ta-4.6Zr alloy by optimizing omega phase precipitation
    M. Nakai; T. Akahori; M. Niinomi; H. Tsutsumi; M. Ogawa
    Processing and fabrication of advanced materials-XVIII 2 787 - 794 2009
  • Fatigue properties of dental restorative alloys
    H. Fukui; S. Tsuruta; M. Niinomi; T. Akahori; M. Nakai; H. Tsutsumi
    Processing and fabrication of advanced materials-XVIII 3 1007 - 1016 2009
  • Fabrication of calcium phosphate ceramic film on Ti-29Nb-13Ta-4.6Zr using MOCVD technique
    H. Tsutsumi; M. Niinomi; T. Akahori; M. Nakai; K. Saito; R. Tu; T. Goto
    Processing and fabrication of advanced materials-XVIII 3 1031 - 1040 2009
  • Mechanical performances of biomedical (Ti, Zr) system alloys through thermo-mechanical treatments
    T. Akahori; M. Niinomi; M. Nakai; H. Tsutsumi; T. Hattori; H. Fukui
    Processing and fabrication of advanced materials-XVIII 3 1061 - 1070 2009
  • Effect of interstitial elements on mechanical performances of Ti-Nb-Ta-Zr alloy for biomedical applications
    F. Geng; M. Niinomi; M. Nakai; T. Akahori; H. Tsutsumi
    Processing and fabrication of advanced materials-XVIII 3 1321 - 1328 2009
  • Effect of rare earth oxides on mechanical properties of Ti-29Nb-13Ta-4.6Zr alloy for biomedical applications
    X. Song; M. Niinomi; H. Tsutsumi; T. Akahori; M. Nakai; S. Yonezawa; L. Wang
    Processing and fabrication of advanced materials-XVIII 3 1329 - 1336 2009
  • Improvement in fatigue properties of spinal implant rod made of Ti-29Nb-13Ta-4.6Zr alloy by cold working and subsequent heat treatments
    K. Narita; M. Niinomi; M. Nakai; T. Akahori; H. Tsutsumi; K. Oribe
    Processing and fabrication of advanced materials-XVIII 3 1355 - 1364 2009
  • Development of new titanium alloys for spinal fixture application
    X. Zhao; M. Niinomi; M. Nakai; T. Akahori; H. Tsutsumi
    Processing and fabrication of advanced materials-XVIII 3 1393 - 1400 2009
  • Effect of severe plastic deformation and thermo-mechanical treatments on microstructures and mechanical properties of β-type titanium alloys for biomedical applications
    H. Yilmazer; M. Niinomi; T. Akahori; M. Nakai; H. Tsutsumi
    Processing and fabrication of advanced materials-XVIII 3 1401 - 1410 2009
  • T. Akahori; M. Niinomi; M. Nakai; H. Tsutsumi
    J. Biomech. Sci. Eng. The Japan Society of Mechanical Engineers 4 (3) 345 - 355 1880-9863 2009 
    Currently, β-type Ti-Nb-Ta-Zr alloys are gaining attention owing to their feasibility for use as biomedical materials. However, the deformation behaviors of these alloys have not yet been clarified. In this study, the Nb content of the Ti-30Nb-10Ta-5Zr (TNTZ) alloy was altered between 1.0 and 3.0 mass% from 30 mass%, and the corresponding changes in the superelasticity and shape-memory characteristics were investigated by tensile loading-unloading tests, X-ray diffraction (XRD) analysis, and microstructural analysis using a transmission electron microscopy (TEM). When the Nb content is less than approximately 29 mass%, the loading-unloading stress-strain curves show two-step gradients and are similar to those of common shape-memory alloys such as Ti-Ni alloys; these gradients result from stress-induced martensitic transformation and its reversion. When the Nb content is approximately 30 mass%, the tensile loading-unloading curves show a nonlinear gradient corresponding to superelastic behavior, which can not be explained by XRD and TEM microstructural analyses on stress-induced martensitic transformation and its reversion in the present state. When the Nb content is approximately 31 mass%, the tensile loading-unloading curves show a single gradient. The elastic deformation is mainly caused by the elastic strain in the lattice. Changes in the chemical content of Nb in TNTZ within a very narrow range are found to alter the superelastic behavior of this alloy.
  • Mitsuo Niinomi; Masaaki Nakai; Toshikazu Akahori; Harumi Tsutsumi; Hideaki Yamanoi; Shinichi Itsuno; Naoki Haraguchi; Yoshinori Itoh; Tadashi Ogasawara; Takashi Onishi; Taku Shindoh
    Ceramic Transactions AMER CERAMIC SOC 206 91 - 101 1042-1122 2009 [Refereed]
     
    Metallic biomaterials with a higher Young's modulus than that of a bone adversely affect bone healing and remodeling. Therefore, it is important to develop the metallic biomaterials having a low Young's modulus. Porous materials are advantageous from this viewpoint because the Young's modulus decreases with increasing porosity. However, with an increase in porosity, the other mechanical properties start deteriorating simultaneously. In comparison with metallic biomaterials, polymers exhibit lower Young's moduli; therefore, a polymer filling is a possible option to improve the mechanical properties of porous materials by preventing the stress concentration at the pores without increasing the Young's modulus. Furthermore, certain polymers exhibit intrinsic biofunctionalities. Thus, a polymer filling is expected to prevent an increase in the Young's modulus and impart biofunctionalities to porous materials without deteriorating their mechanical properties. In this study, porous pure titanium (pTi) with a porosity of 22%-50% and filled with a medical polymer (polymethylmethacrylate: PMMA) (pTi/PMMMA) was firstly fabricated. The effects of the PMMA filling on the tensile strength of pTi were then investigated. However, the deterioration of mechanical properties was not satisfactorily prevented because of the poor interfacial adhesiveness between the titanium particles and the medical polymer. Therefore, in the present study, silane-coupling treatment was employed in order to improve the interfacial adhesiveness, and silane-coupling-treated (Si-treated) pTi filled with PMMA (Si-treated pTi/PMMA) was fabricated. The effect of the silane-coupling treatment on the mechanical properties of pTi/PMMA was investigated.It is found that the PMMA filling improves the tensile strength of pTi that has a porosity of over 40%. The tensile strengths of Si-treated pTi/PMMA are greater than those of pTi and pTi/PMMA. In the fractographs of pTi/PMMA obtained after the tensile test, the detachment of titanium particles from PMMA is observed; this occurs because of poor interfacial adhesiveness between titanium particles and PMMA. However, in the case of Si-treated pTi/PMMA, the interfacial adhesiveness between titanium particles and PMMA is improved by the silane-coupling treatment. This leads to the dispersion of the stress concentration at the necks between particles, resulting in an improvement in the tensile strength of pTi. On the other hand, the PMMA filling hardly affects the Young's modulus of pTi because the Young's modulus of PMMA is lower than that of pTi.
  • Kengo Narita; Mitsuo Niinomi; Masaaki Nakai; Toshikazu Akahori; Harumi Tsutsumi; Kazuya Oribe; Takashi Tamura; Shinji Kozuka; Shizuma Sato
    Ceramic Transactions AMER CERAMIC SOC 206 83 - 90 1042-1122 2009 
    Implanting a spinal fixture by using implant rods is one of the effective treatments for spinal diseases. Most of the implant rods are made of the Ti-6Al-4V ELI alloy (Ti64). However, some problems regarding using Ti64 rods have been pointed out; these rods contain vanadium, which is highly toxic to the human body, and exhibit a considerably higher Young's modulus than the cortical bone. The Ti-29Nb-13Ta-4.6Zr alloy (TNTZ) developed by the authors exhibits good biocompatibility due to its nontoxic- and nonallergic- components. Further, TNTZ has a lower Young's modulus as compared to Ti64. It is expected that implant rods made of TNTZ exhibiting low Young's modulus will prevent the accelerated degeneration of the segment adjacent to a fusion. The mechanical properties of TNTZ rods subjected various heat treatments are comprehensively evaluated through tensile tests, Young's modulus measurement, and four-point bending fatigue tests based on the ASTM F2193 standard and compared with those of Ti64 rods. Among the TNTZ rods used in this study, the TNTZ rod aged at 673 K (Rod(673) (K)) exhibits the highest tensile strength because of the precipitation of the isothermal omega-phase and alpha-phase in it. The tensile strength of Rod(673) (K) exceeds that of Ti64, while the increase in Young's modulus of the former is suppressed below that of the latter. With regards to four-point bending fatigue strength, no advantages are obtained from every TNTZ rods in comparison with Ti64 rod.
  • Masaaki Nakai; Mitsuo Niinomi; Toshikazu Akahori; Hideaki Yamanoi; Shinichi Itsuno; Naoki Haraguchi; Yoshinori Itoh; Tadashi Ogasawara; Takashi Onishi; Taku Shindoh
    8th World Biomaterials Congress 2008 1 322  2008/12
  • Masaaki Nakai; Mitsuo Niinomi; Toshikazu Akahori; Hiroshi Ishikawa; Michiharu Ogawa
    JOURNAL OF THE JAPAN INSTITUTE OF METALS JAPAN INST METALS 72 (12) 960 - 964 0021-4876 2008/12 [Refereed]
     
    The effect of oxygen content on the microstructure and mechanical properties of Ti-29Nb-13Ta-4.6Zr (TNTZ) solutionized and aged at 723 K was investigated. The microstructure of solutionized TNTZ consists of a single,6 phase, and addition of oxygen leads to the increase in the hardness and tensile strength because of solid solution hardening, and the increase in Young's modulus, and the decrease in the elongation. On the other hand, the alpha phase precipitates in the aged TNTZ. The results of transmission electron microscopy and X-ray diffraction imply that the size and volume fraction of the alpha phase increase with the oxygen content in the aged TNTZ. The mechanical properties of the aged TNTZ change with the oxygen content. Age hardening in aged TNTZ is enhanced by an increase in the oxygen content. Further, with an increase in the oxygen content, both the tensile strength and Young's modulus increase, while elongation decreases due to the precipitation of the alpha phase. TNTZ with different mechanical properties (Young's modulus: around 60-100 GPa, tensile strength: around 600-1400 MPa, elongation: around 5-25%) can be obtained depending on the oxygen content and the heat treatment technique.
  • Toshikazu Akahori; Mitsuo Niinomi; Masaaki Nakai; Harumi Tsutsumi; Takahiro Nozaki; Satoshi Horihata; Toru Suzuki; Keiji Sone
    Keikinzoku/Journal of Japan Institute of Light Metals 58 (11) 604 - 610 0451-5994 2008/11 
    Binary titanium alloys containing Nb or Ta, which are allergy-free and non-toxicity elements, were fabricated, and then the possibility of their application to various music instruments made of brass was investigated by the evaluation of corrosion characteristics, elastic modulus-density ratio (E/ρ), resonance frequency (f) and internal friction (Q -1). The practical models of the mouthpieces of the trumpets made of the binary titanium alloys were also fabricated by precision casting method in order to compare directly with the sound characteristics of those made of brass and commercially pure Ti. The critical current density for the passivation of the Ti-Nb and Ti-Ta system alloys is approximately 40% lower than that of brass and nearly equal to or a little higher than that of commercially pure Ti. The Q -1 of the Ti-Nb and Ti-Ta system alloys with α″ phase drastically increase. The E/ρ and f of the Ti-Nb and Ti-Ta system alloys exhibit a positive relationship. The sound characteristics of practical mouthpieces of trumpets for a bass instrument can be controlled by changing the E/ρ and/of the alloys.
  • Masaaki Nakai; Mitsuo Niinomi; Toshikazu Akahori; Hideaki Yamanoi; Shinichi Itsuno; Naoki Haraguchi; Yoshinori Itoh; Tadashi Ogasawara; Takashi Onishi; Taku Shindoh
    JOURNAL OF THE JAPAN INSTITUTE OF METALS JAPAN INST METALS 72 (10) 839 - 845 0021-4876 2008/10 [Refereed]
     
    As a new type of metallic biomaterial, porous pure titanium filled with a medical polymer has been developed for obtaining a low Young's modulus similar to that of bone. This type of biomaterials will inhibit the deterioration of mechanical properties due to the presence of pores, and provide biofunctionalities that are intrinsically possessed in certain polymers. However, the inhibition of the deterioration of mechanical properties is not satisfactory because of the poor interfacial adhesiveness between the titanium particles and the medical polymer. Therefore, in the present study, silane coupling treatment is employed in order to improve the interfacial adhesiveness, and silane-coupling-treated (Si-treated) porous pure titanium (pTi) filled with polymethylmethacrylate (PMMA) is fabricated. Subsequently, the effect of the silane coupling treatment on the mechanical properties of the pTi filled with PMMA is investigated.The tensile strengths of the Si-treated pTi filled with PMMA are higher than those of pTi and non-Si-treated pTi filled with PMMA. In the fractographs of non-Si-treated pTi filled with PMMA obtained after the tensile test, the detachment of titanium particles from PMMA is observed; this occurs because of poor interfacial adhesiveness between titanium particles and PMMA. However, in the case of the Si-treated pTi filled with PMMA, the interfacial adhesiveness between titanium particles and PMMA is improved by the silane coupling treatment. This leads to the dispersion of the stress concentration at necks between particles, resulting in an improvement in the tensile strength of pTi. On the other hand, PMMA filling hardly affects Young's modulus of pTi because Young's modulus of PMMA is lower than that of pTi.
  • Kengo Narita; Mitsuo Niinomi; Masaaki Nakai; Toshikazu Akahori; Kazuya Oribe; Takashi Tamura; Shinzi Kozuka; Shizuma Sato
    JOURNAL OF THE JAPAN INSTITUTE OF METALS JAPAN INST METALS 72 (9) 674 - 678 0021-4876 2008/09 
    Installing a spinal fixture using implant rods is one of the effective operations for spinal diseases. Most of the implant rods are made of Ti-6Al-4V ELI alloy (Ti64). However, some problems regarding the Ti64 rod have been pointed out; it contains vanadium, which is considerably toxic to the human body, and exhibits a much higher Young's modulus than that of the cortical bone. Ti-29Nb-13Ta-4.6Zr alloy (TNTZ) developed by the authors exhibits good biocompatibility due to its nontoxic- and allergy- free elements, and has a lower Young's modulus than that of Ti64. In addition, the mechanical properties of TNTZ can be changed drastically according to various heat treatments. The mechanical properties of TNTZ rods subjected to various heat treatments have been investigated in this study. The as-solutionized TNTZ rod consists of a single beta phase. Isothermal omega phase and alpha phase precipitate in the beta phase of the TNTZ rod aged at 673 K for 259.2 ks. Only alpha phase precipitates in the beta phase of the TNTZ rod aged at 723 K for 259.2 ks. Tensile strength and 0.2% proof stress become larger in order of as-solutionized TNTZ rod, TNTZ rod aged at 723 K for 259.2 ks and TNTZ rod aged at 673 K for 259.2 ks, while elongation is smaller in order of as-solutionized TNTZ rod, TNTZ rod aged at 723 K for 259.2 ks and TNTZ rod aged at 673 K for 259.2 ks. Young's modulus become larger in order of as-solutionized TNTZ rod, TNTZ rod aged at 723 K for 259.2 ks and TNTZ rod aged at 673 K for 259.2 ks.
  • Toshikazu Akahori; Mitsuo Niinomi; Masaaki Nakai; Michiharu Ogawa
    Zairyo/Journal of the Society of Materials Science, Japan 57 (9) 893 - 898 0514-5163 2008/09 
    Relationships between fatigue properties and microstructures of hot-forged Ti-29Nb-13Ta-4.6Zr alloy (TNTZ) in under aged, peak aged, and over aged conditions at aging temperatures of 673K and 723K are investigated. The changes in the fatigue properties of TNTZ subjected to thermomechanical treatments, which includes an aging treatment at 673K or 723K for 259.2ks after a severe deformation process by cold rolling, are also investigated. At an aging temperature of 673K, ω phase precipitates at the early stage of aging, but α phase precipitates at relatively longer aging time. The precipitation site of α phase changes from intra-grain to grain boundary at around peak aging time when TNTZ is aged at 673K and 723K. The elastic modulus of TNTZ increases simply with increasing aging time at both 673K and 723K The fatigue strength of TNTZ increases considerably when α phase precipitates compared with when ω+α phases co-exist. The fatigue strength of TNTZ decreases slightly due to the coarsening of α phase precipitated in β grain and its grain boundary. TNTZ aged at 723K for 259.2ks after cold rolling exhibits the highest fatigue strength in both the low- and high-cycle fatigue life regions. Furthermore, the fatigue limitof about 770MPa (fatigue raito : 0.71) is nearly equal to that of hot-forged Ti-6Al-4V ELI alloy subjected to aging after solution treatment with equiaxed α structure. © 2008 The Society of Materials Science.
  • Y. Tanaka; M. Nakai; T. Akahori; M. Niinomi; Y. Tsutsumi; H. Doi; T. Hanawa
    CORROSION SCIENCE PERGAMON-ELSEVIER SCIENCE LTD 50 (8) 2111 - 2116 0010-938X 2008/08 
    The surface oxide film on a Ti-29Nb-13Ta-4.6Zr alloy (TNTZ) was precisely characterized using X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) to understand the composition and chemical state of the surface oxide film of TNTZ. For comparison, the component metals, titanium, niobium, tantalum, and zirconium, were also characterized to consider the effect of those on the formation of the surface oxide film on their alloy. The characterization of the surface oxide films on TNTZ and its component revealed the following issues. The surface oxide film on TNTZ consists of a composite oxide that contains titanium, niobium, tantalum, and zirconium but forms continuous layer and is very thin, ca. 3.7 nm. The oxide film is not completely oxidized because it contains various valences of cations. In particular, the oxidation of tantalum is inhibited in the oxide. Tantalum is enriched in the substrate in TNTZ just under the surface oxide because of this inhibition in the oxidation. The formation of the surface oxide film in TNTZ is predominantly governed by titanium. The preferential oxidation of an element is not always dependent on the initial oxidation potential of that element, the relationship between the oxidation energy from a smaller valence to a larger valence, and the dehydration process. In other words, a complicated competition governs the resultant composition of surface oxide. (C) 2008 Elsevier Ltd. All rights reserved.
  • Masaaki Nakai; Mitsuo Niinomi; Toshikazu Akahori; Naofumi Ohtsu; Hideki Nishimura; Hiroyuki Toda; Hisao Fukui; Michiharu Ogawa
    MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING ELSEVIER SCIENCE SA 486 (1-2) 193 - 201 0921-5093 2008/06 [Refereed]
     
    The microstructure and hardness near the surface of a biomedical titanium alloy, Ti-29Nb-13Ta-4.6Zr (TNTZ), subjected to gas nitriding at 1023-1223 K was investigated in comparison with the conventional biomedical Ti-6Al-4V ELI (Ti64). After gas nitriding, the microstructure near the specimen surface was observed by optical microscopy, X-ray diffraction (XRD), Auger electron spectroscopy (AES), and X-ray photoelectron spectroscopy (XPS). In both alloys, two types of titanium nitrides (TiN and Ti(2)N) are formed and the a phase is precipitated by gas nitriding. Furthermore, the oxygen impurity in the gas nitriding atmosphere reacts with the titanium nitrides; thus, TiO(2) is formed at the outermost titanium nitride layer. The surface hardening was also evaluated by Vickers hardness measurement. The Vickers hardness near the surface of TNTZ and Ti64 increases significantly by gas nitriding. (c) 2007 Published by Elsevier B.V.
  • Masaaki Nakai; Mitsuo Niinomi; Toshikazu Akahori; Hideaki Yamanoi; Shinichi Itsuno; Naoki Haraguchi; Yoshinori Itoh; Tadashi Ogasawara; Takashi Onishi
    Funtai Oyobi Fummatsu Yakin/Journal of the Japan Society of Powder and Powder Metallurgy 55 (5) 312 - 317 0532-8799 2008/05 
    High Young's modulus of metallic biomaterials in comparison with that of bone affects harmfully on bone healing and remodeling. Therefore, it is important to decrease Young's modulus of the metallic biomaterials. In that case, porous materials are advantageous from the viewpoint of obtaining a lower Young's modulus, because Young's modulus decreases with increasing porosity of the porous materials. However, with an increase in porosity, the other mechanical properties start deteriorating simultaneously. This deterioration of the mechanical properties is probably derived from the stress concentration at the pores of the porous materials. In comparison with metallic biomaterials, polymers exhibit lower Young's moduli thus a polymer filling is a likely option to improve the mechanical properties of porous materials by preventing the stress concentration at the pores without increasing the Young's modulus. Furthermore, certain polymers exhibit intrinsic biofunctionalities, Thus, polymer filling is expected to improve the mechanical properties and impart biofunctionalities to porous materials without an increase in its Young's modulus. In this study, the pores of porous pure titanium (pTi) with the porosity of 22-50% were filled with a medical polymer (polymethylmethacrylate: PMMA). The effects of PMMA filling on the tensile strength and Young's modulus of pTi were then investigated. As a result, it is found that the PMMA filling improves the tensile strength of pTi with the porosity over 40%, although not significantly affecting the Young's modulus of pTi.
  • Mitsuo Niinomi; Toshikazu Akahori; Masaaki Nakai
    MATERIALS SCIENCE & ENGINEERING C-BIOMIMETIC AND SUPRAMOLECULAR SYSTEMS ELSEVIER SCIENCE BV 28 (3) 406 - 413 0928-4931 2008/04 [Refereed]
     
    Ti-XNb-10Ta-5Zr (mass %) alloys based on nominal compositions of Ti-35Nb-IM-5Zr,Ti-30Nb-10Ta-5Zr, and Ti-25Nb-10Ta-5Zr were fabricated through powder metallurgy and forging and swaging processes for biomedical applications. The tensile deformation mechanisms of the Ti-25Nb-10Ta-5Zr, Ti-30Nb-10Ta-5Zr, and Ti-35Nb-10Ta-5Zr alloys were investigated in situ by X-ray diffraction analysis under several loading conditions. Under the loading conditions, the X-ray diffraction peaks of all the specimens shifted to higher angles than those obtained under the unloading conditions. For the Ti-30Nb-10Ta-5Zr alloy, the elastic deformation is considered to progress continuously in a different crystal direction although after the elastic strain reaches elastic limit in the crystal direction where the elastic limit is the smallest, slip deformation occurs in that crystal direction. The elastic modulus of this alloy appears to decrease in terms of strain over the proportional limit. Thus, the elastic deformation behavior of the Ti-30Nb-10Ta-5Zr alloy does not obey Hooke's law. (c) 2007 Elsevier B.V. All rights reserved.
  • Toshikazu Akahori; Mitsuo Niinomi; Masaaki Nakai; Toshihiro Kasuga; Michiharu Ogawa
    MATERIALS TRANSACTIONS JAPAN INST METALS 49 (2) 365 - 371 1345-9678 2008/02 [Refereed]
     
    Beta-type titanium alloys used in biomedical applications have been developed all over the world. In particular, Ti-29Nb-13Ta-4.6Zr alloy (TNTZ) is one of beta-type titanium alloys for biomedical applications that has been developed by the authors in Japan. Although TNTZ is composed of non-toxic elements such as niobium, tantalum, and zirconium, it still lacks bioactivity, which is the ability to form chemical bonds with living bones. The stems that are parts of artificial hip joints, dental implants, etc., which are made of metallic materials, etc. are required to bond strongly with living bones. However, these stems, dental implants etc., cannot form chemical bond with living bones by themselves. The bioactive surface modification of metallic materials by the application of ceramics is effective in improving the biocompatibility of TNTZ. Calcium phosphate ceramics such as hydroxyapatite (Ca-10(PO4)(6)OH2; HAP) and beta-tricalcium phosphate (beta-Ca-3(PO4)(2); beta-TCP) possess bioactivity. In this study, the characteristics and morphology of TNTZ coated with a calcium phosphate invert-glass-ceramic (CPIG) layer by dip-coating treatment or with a sodium titanate layer by alkali solution treatment are investigated before and after soaking it in a simulated body fluid (SBF). The bonding strength between a CPIG layer with a thickness of around 5 mu m and a specimen surface of TNTZ is around 25 MPa. No cracks or exfoliations are observed along the boundary between the CPIG layer and the specimen surface. This is the reason why the difference in the thermal expansion coefficients between CPIG layer and TNTZ reduced due to a compositional gradient zone with a thickness of around 3 mu m in CPIG layer. HAP is formed on the entire surface of the TNTZ specimen after soaking it in the SBF for more than 1728 ks. The fatigue properties of TNTZ coated with a CPIG layer are similar to those of as-solutionized TNTZ. A reticulate structure with a thickness of 400 to 800 nm is formed on the TNTZ specimen surface after soaking it in 3 to 10 kmol/m(3) NaOH solution for 86.4 ks and 172.8 ks. HAP is completely formed on the entire surface of the TNTZ specimen when it is soaked in the SBF for 1209.6 ks after being soaked in 5 kmol/m(3) NaOH solution for 172.8 ks.
  • M. Niinomi; T. Akahori; M. Nakai; N. Kawakita
    MEDICAL DEVICE MATERIALS IV ASM INTERNATIONAL 130 - 135 2008 
    The Nb content of TNTZ (Ti-29Nb-13Ta4.6Zr) was changed by 1 mass% to 2 mass% below 30 mass%. The change in the behavior of functionalities such as superelasticity and the shape- memory effect was investigated by tensile loading-unloading tests, X-ray analysis and differential scanning calorimetric (DSC) analysis. When the Nb content is below approximately 28 mass%, the tensile loading-unloading stress-stain curve is similar to that representing the general shape-memory behavior, which occurs due to deformation induced martensitic transformation and its reversion. When the Nb content ranges from approximately 29 mass% to 30 mass%, the tensile loading-unloading curve exhibits superelastic behavior that cannot be explained by deformation- induced martensitic transformation and its reversion. A change in the chemical content of Nb in TNTZ within a very narrow range alters the superelastic behavior of this alloy.
  • M. Naka; M. Niinomi; T. Akahori; Y. Shinozaki; S. Itsuno; N. Haraguchi; Y. Itoh; T. Ogasawara; T. Onishi
    POROUS METALS AND METALLIC FOAMS DESTECH PUBLICATIONS, INC 283 - 286 2008 
    Low Young's modulus is an important property for metallic biomaterials. Porous materials are advantageous from the point of view of obtaining a lower Young's modulus. However, with a decrease in Young's modulus, the other mechanical properties start deteriorating simultaneously. In comparison with metallic biomaterials, polymers exhibit lower Young's moduli; and thus a polymer filling is a likely option to improve the mechanical properties of porous materials by preventing the stress concentration at the pores without increasing the Young's modulus. Furthermore, certain polymers exhibit intrinsic biofunctionalities. Thus, polymer filling is expected to prevent an increase in the Young's modulus and impart biofunctionalities to porous materials without the deterioration of its mechanical properties. In this study, the pores of porous pure titanium (pTi) were filled with a medical polymer (polymethylmetbacrylate: PMMA). The effects of PMMA filling on the mechanical properties of pTi were then investigated.
  • Effect of silane coupling treatment on mechanical properties of biomedical titanium/polymer composite
    M. Nakai; M. Niinomi; T. Akahori; H. Tsutsumi; H. Yamanoi; S. Itsuno; N. Haraguchi; Y. Itoh; T. Ogasawara; T. Onishi; T. Shindoh
    Processing and fabrication of advanced materials-XVII (I.K. International Publishing House Pvt. Ltd.) 811 - 818 2008
  • Mechanical biocompatibility of low-modulus beta-type Ti-29Nb-13Ta-4.6Zr in biomedical applications
    M. Niinomi; T. Akahori; M. Nakai; H. Tsutsumi; T. Hattori; K. Morikawa; H. Hashimoto
    Processing and fabrication of advanced materials-XVII (I.K. International Publishing House Pvt. Ltd.) 767 - 774 2008
  • Toshikazu Akahori; Mitsuo Niinomi; Masaaki Nakai; Wataru Kawagishi; Hisao Fukui
    Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals 72 (1) 63 - 71 0021-4876 2008/01 
    Dental Ag-Pd-Cu-Au-Zn system alloy, which is a semi-precious alloy, is one of the most widely used metallic dental materials in Japan due to its excellent mechanical properties and corrosion resistance and applicability to health insurance. Dental products, e.g., inlays and crowns, fabricated from this alloy are used under cyclic loading conditions including frictional wear, when it comes in contact with the same or other dental materials in the oral cavity or an opposing tooth during mastication. The effects of microstructures of Ag-20 mass%Pd-14.5 mass%Cu-12 mass%Au-2 mass%Zn alloy on the fretting-fatigue properties are, therefore, investigated in this study. The fretting-fatigue strength of the Ag-20 mass%Pd-14.5 mass%Cu-12 mass%Au-2 mass%Zn alloy subjected to solution treatment (ST) and aging treatment (AT) decreases significantly as compared to the fatigue strength without fretting (plain-fatigue strength). Moreover, the fretting-fatigue strength after the AT decreases by approximately 60% as compared to that after the ST, especially in the high-cycle fatigue life region. Several traces of fretting wear are observed to be distributed in the slip region of both materials. These wear traces are generated due to the accumulation of wear debris on the fretting pad or the fretting fatigue specimen. These traces of fretting wear are distributed more closely in the slip region of the AT material. Therefore, the fatigue life decreases significantly because the fretting fatigue crack initiation life and the propagation life decrease in the AT material. © 2008 The Japan Institute of Metals.
  • Toshikazu Akahori; Mitsuo Niinomi; Masaaki Nakai; Hideki Nishimura; Yukiko Takei; Hisao Fukui; Michiharu Ogawa
    MATERIALS TRANSACTIONS JAPAN INST METALS 49 (1) 166 - 174 1345-9678 2008/01 [Refereed]
     
    Frictional wear resistance is one of the important properties of metallic biomaterials. Surface hardening treatments such as oxidizing, nitriding and ion implantation tend to be applied for improving the wear resistance of titanium and its alloys. The simple gas nitriding process is expected to further improve the wear resistance of newly developed beta-type Ti-29Nb-13Ta-4.6Zr alloy (TNTZ) for biomedical applications. However, there is a possibility for the mechanical properties such as tensile and fatigue strength of TNTZ to be degraded through gas nitriding process. Therefore, the gas nitriding process was carried out in this study to improve the wear resistance of TNTZ and alpha+beta-type Ti-6Al-4V ELI alloy (Ti64), which is one of the representative titanium alloys practically applied for biomedical applications, in simulated body fluid (Ringer's solution). Their tensile and fatigue properties and cell viability was also investigated in order to confirm the reliability as biomedical materials. The Vickers hardness near the specimen surface of nitrided TNTZ and Ti64, where TiN and Ti2N forms. increases significantly as compared to that of their matrices. The wear resistances of TNTZ and Ti64 are improved significantly in Ringer's solution by nitriding process as compared to those of as-solutionized TNTZ (TNTZ(ST)) and Ti64 (Ti64(ST)). The tensile strength of nitrided TNTZ increases by around 90 MPa as compared to that of TNTZST. The tensile strength of nitrided Ti64 does not change significantly at all nitriding temperatures. On the other hand, the elongation decreases with increasing the nitriding temperature. The run out (plain fatigue limit) of TNTZ subjected to a nitriding process at 1123 K, which has relatively good balance between wear resistance and tensile properties, is around 300 MPa, and is nearly equal to that of Ti64 subjected to a nitriding process at 1123 K, although the tensile strength of the nitrided TNTZ is around 200 MPa smaller than that of the nitrided Ti64. The cell viabilities of nitrided TNTZ and Ti64 range from 1.4 to 1.6 against that of control (cell disc), and are a little higher than that of TNTZ(ST) and Ti64(ST). The cell viabilities of nitrided TNTZ and Ti64 after removing the oxide layer on their surfaces are similar to that of control and are not significantly degraded.
  • Mitsuo Niinomi; Masaaki Nakai; Toshikazu Akahori
    BIOMEDICAL MATERIALS IOP PUBLISHING LTD 2 (3) S167 - S174 1748-6041 2007/09 [Refereed]
     
    The frictional wear characteristics of Ti-29Nb-13Ta-4.6Zr alloy subjected to solution treatment ( referred to as TNTZ(ST)) and aged at 598, 673 and 723 K after solution treatment ( referred to as TNTZ(598K), TNTZ(673K) and TNTZ(723K), respectively) were investigated in air and a simulated body environment ( Ringer's solution) as a function of the loading level. Ti-6Al-4V ELI alloy aged at 813 K after solution treatment ( referred to as T64(STA)) was employed as a reference material. Wear weight losses of TNTZST, TNTZ(598K), TNTZ(673K), TNTZ(723K) and Ti64(STA) are lower in Ringer's solution than in air under both low and high loading conditions (1.96 and 29.4 N, respectively). It is considered that the frictional factor decreases because of the lubricating effect of Ringer's solution between the contact surface of the specimen and the zirconia ball - the mating material. Moreover, the wear weight losses of TNTZ(598K), TNTZ(673K) and TNTZ(723K) are lower than that of Ti64(STA) in both air and Ringer's solution under the low loading condition, but are higher under the high loading condition. This result implies that the transition from severe wear to mild wear versus loading level depends on the type of material.
  • Toshikazu Akahori; Mitsuo Niinomi; Manabu Watanabe; Masaaki Nakai; Hisao Fukui; Michiharu Ogawa
    Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals 71 (4) 407 - 414 0021-4876 2007/04 
    The frictional wear characteristics of heat-treated Ti-29Nb-13Ta-4.6Zr (TNTZ) subjected to solution treatment (TNTZST) or aging treatments at 598, 673, and 723 K, respectively after solution treatment (TNTZ 598 K, TNTZ673 K, and TNTZ 723 K, respectively) and Ti-6Al-4V ELI (Ti64) subjected to aging treatment after solution treatment (T64STA) in air and simulated body environment (Ringer's solution) were investigated as a function of load in this study. Wear weight losses of TNTZST, TNTZ598 K, TNTZ673 K, TNTZ 723 K, and Ti64STA are smaller in Ringer's solution than in air under both low and high loading conditions (1.96 and 29.4N, respectively). This is considered to suggest that the frictional coefficient decreased because of the lubricant effect of Ringer's solution between the contact surfaces of specimen and zirconia ball as mating material. The wear losses of TNTZST, TNTZ598 K, TNTZ673 K, TNTZ723 K, and Ti64STA increase with increasing load in Ringer's solution. The wear losses of TNTZST, TNTZ598 K, TNTZ698 K, and TNTZ723 K at a low loading level are smaller than that of Ti64STA in Ringer's solution. On the other hand, the wear losses of TNTZ598 K and TNTZ673 K at a high loading level are larger than that of Ti64STA in Ringer's solution. This reason is that the transition point from sever wear to mild wear versus load is changed according to the materials. © 2007 The Japan Institute of Metals.
  • Masaaki Nakai; Mitsuo Niinomi; Toshikazu Akahori; Naofumi Ohtsu; Hideki Nishimura; Hiroyuki Toda; Hisao Fukui; Michiharu Ogawa
    JOURNAL OF THE JAPAN INSTITUTE OF METALS JAPAN INST METALS 71 (4) 415 - 422 0021-4876 2007/04 
    Formation of the reaction product layer on the surface of biomedical titanium alloys, Ti-29Nb-13Ta-4.6Zr (TNTZ) and Ti6A1-4V ELI (Ti64), during gas nitriding was investigated. These alloys were exposed to nitrogen atmosphere at 1023, 1073, 1123 and 1223 K. After the gas nitriding, a reaction product layer was observed on the surface of both alloys, and was analyzed using an X-ray diffraction (XRD), Auger electron spectroscopy (AES) and X-ray Photoelectron spectroscopy (XPS). The layer was comprised of two phases, which were outer oxide layer (mainly TiO2) and inner nitride layer (mainly TiN or Ti2N). In these layers, the thickness of the oxide layer particularly depended on the kinds of alloys. According to the thermodynamics and point defect theory, the growth rate of oxide layer is expected to be increased by the presence of Al in TiO2. Namely, the dissolution of Al into TiO2 may increase the number of oxygen vacancies, resulting in acceleration of oxygen diffusion inward. On the other hand, the elements that accelerate the growth of the oxide layer are not contained in TNTZ. Thus, the oxide layer formed on Ti64 was thicker than that of TNTZ. In a similar way, the elements that accelerate the growth of the nitride layer are not contained in both TNTZ and Ti64. Thus, the nitride layers with similar thicknesses may be formed on TNTZ and Ti64 during gas nitriding.
  • Toshikazu Akahori; Mitsuo Niinomi; Masaaki Nakai; Hidetsugu Fukuda; Hisao Fukui; Michiharu Ogawa
    MATERIALS TRANSACTIONS JAPAN INST METALS 48 (3) 293 - 300 1345-9678 2007/03 
    Biomedical /3-type titanium alloys have been developed or are under development all over the world. In particular, researchers in Japan have been developed Ti-29Nb-13Ta-4.6Zr alloy (TNTZ)-beta-type titanium alloy-for biomedical applications. Bioactive ceramic surface modification is effective for further improvement in the biocompatibility of TNTZ. Calcium phosphate ceramics such as hydroxyapatite (Ca-10(PO4)(6)OH2; HAP), beta-calcium pyrophosphate (beta-CaP2O7; CPP), and P-tricalcium phosphate (beta-Ca-3(PO4)(2); beta-TCP) exhibit bioactivity. In this study, the formability and morphology of HAP on the surface of TNTZ, covered with sodium titanate film by alkali solution treatment were investigated before and after immersion in a simulated body fluid (SBF). A reticulate structure with a considerable number of large cracks and mainly composed of sodium titanate and niobate films having a thickness of 400 nm to 800 nm is formed on the specimen surface of TNTZ after immersing in 3, 5, and 10 kmol(.)m(-3) NaOH solutions for 86.4 and 172.8 ks. As the concentration of the alkali solution and the immersion time are increased, the formability of HAP improves because of the presence of a large amount of oxygen and the sodium in sodium titanate and mobate film. HAP is completely formed on the entire specimen Surface of TNTZ immersed in the SBF for 1209.6ks after immersing in 5 and 10 kmol(.)m(-3) NaOH solutions for 172.8 ks. Alkali treatment at 333 K in 5 kmol(.)m(-3) NaOH solutions for 172.8 ks is proposed to be an excellent condition to rapidly form HAP and fully cover the specimen surface of TNTZ with it. The bonding strength between TNTZ (alkali treatment at 333 K in 5 kmol(.)m(-3) NaOH solutions for 172.8 ks) and HAP is around 2 MPa, which was half or less than half the value required for biomedical applications. The inclusion of a baking treatment after the alkali treatment in order to improve the bonding strength degraded the HAP formability. Furthermore, the formability decreases with an increase in the baking temperature.
  • Y. Zhou; M. Niinomi; T. Akahori; M. Nakai; H. Fukui
    Mater. Trans. 日本金属学会 48 (3) 380 - 384 1345-9678 2007/03 [Refereed]
  • Mitsuo Niinomi; Toshikazu Akahori; Masaaki Nakai; Kazuma Ohnaka; Yoshinori Itoh; Kenji Sato; Tomoya Ozawa
    Innovations in Titanium Technology MINERALS, METALS & MATERIALS SOC 209 - 217 2007 
    Metal injection molding (MIM) is a cost-saving process for fabricating products that have complicated shapes with a very high accuracy of size. It is expected that MIM will be employed as a new process for fabricating orthopedic and dental products with complicated shapes. The mechanical properties of Ti-6Al-4V, particularly its tensile and fatigue properties, fabricated by MIM (Ti64) were investigated to determine their suitability for medical applications. In order to improve the reliability of Ti64 for biomedical applications, the effects of heat treatments, and the addition of an element (Mo) on its mechanical properties were also investigated. The 0.2% proof stress, tensile strength and elongation of Ti64 are approximately 740 MPa, 850 MPa, and 12%, respectively. The volume fraction of the pores is around 1.1%. The tensile strength of Ti64 subjected to heat treatment at 1323 K for 3.6 ks followed by air cooling and hot rolling increases by around 24%. However, it is difficult to improve the strength-elongation balance because the elongation decreases after heat treatment and hot rolling. The strength elongation balance of Ti64 is improved by hot isostatic pressing (HIP): the tensile strength and elongation are around 960 MPa and 13%, respectively. The tensile strength of Mo added Ti64 that contains Mo (Ti-6Al-4V-3Mo) increases by around 15% in comparison with that of Ti64. The elongation of both the alloys is almost the same. The size of the pores of Ti64 is reduced drastically by HIP The fatigue strengths of Ti64 subjected to HIP is the highest in the low- and high-cycle fatigue-life regions. Its fatigue strength is comparable to that of wrought Ti-6Al-4V.
  • Fretting Fatigue Characteristics and Microstructures of Dental Low Noble Ag-Pd-Cu-Au-Zn Alloy
    M. Niinomi; T. Akahori; M. Nakai; W. Kawagishi; H. Fukui
    Proc. international Conference on Advanced Technology in Experimental Mechanics 2007 (ATEM'07), Sep. 2007, Fukuoka, Japan CD-ROM 2007
  • Mechanical Performance of Biomedical β-Type Titanium Alloy Subjected to Surface Hardening Treatment
    T. Akahori; M. Niinomi; M. Nakai
    Proc. international Conference on Advanced Technology in Experimental Mechanics 2007 (ATEM'07), Sep. 2007, Fukuoka, Japan CD-ROM 2007
  • M. Nakai; M. Niinomi; T. Akahori; Y. Shinozaki; H. Toda; S. Itsuno; N. Haraguchi; Y. Itoh; T. Ogasawara; T. Onishi
    Proc. international Conference on Advanced Technology in Experimental Mechanics 2007 (ATEM'07), Sep. 2007, Fukuoka, Japan The Japan Society of Mechanical Engineers CD-ROM 2007
  • Development of Titanium Alloy for Mouthpiece of Brass Instrument and Its Precision Casting Process
    M. Niinomi; T. Akahori; T. Nozaki; M. Nakai; T. Suzuki; K. Wakanabe; K. Sone; H. Toda
    Ti-2007 Science and Technology (The Japan Institute of Metals) 1571 - 1574 2007
  • Wear Resistance and Mechanical Properties of Biomedical β-type Ti-Nb-Ta-Zr System Alloy Subjected to Gas Nitriding Process
    T. Akahori; M. Niinomi; M. Nakai; H. Nishimura; H. Fukui; M. Ogawa
    Ti-2007 Science and Technology (The Japan Institute of Metals) 1461 - 1465 2007
  • M. Nakai; M. Niinomi; T. Akahori; Y. Shinozaki; H. Toda; S. Itsuno; N. Haraguchi; Y. Itoh; T. Ogasawara; T. Onishi
    Ti-2007 Science and Technology (The Japan Institute of Metals) 1497 - 1500 2007
  • Evaluation of Ti-Nb-Ta-Zr as New Medical Implants
    T. Tamura; S. Kozuka; K. Oribe; M. Nakai; M. Niinomi
    Ti-2007 Science and Technology (The Japan Institute of Metals) 1441 - 1444 2007
  • Yoshinori Murata; Kensuke Nagai; Masaaki Nakai; Tomonori Kunieda; Masahiko Morinaga
    Nippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals 71 (1) 68 - 75 0021-4876 2007/01 
    High-temperature oxidation of a pure iron, Fe-2Cr alloy, Fe-10Cr alloys and an Fe-10Cr-0.08C steel was examined in both air and steam at 923 K. In case of pure iron, the thickness of the oxide scale formed in steam at 923 K for 360 ks was comparable to that of the scale formed in air. On the other hand, in case of the Fe-Cr binary alloys and the ternary martensitic steel, the oxide scale was much thicker in steam than in air. The amount of hydrogen dissolved into the pure iron and the steels during exposure to the high-temperature steam was measured with thermal desorption spectroscopy (TDS). It was found that the amount of the dissolved hydrogen in the oxide scale was much larger in both the binary alloys and the ternary ferritic steel than in pure iron, and then it leads to the more accelerated oxidation rate of the binary alloys and the ternary steel in the steam. Furthermore, the martensite structure of the ternary steel exhibited an excellent oxidation resistance in air compared to the ferrite phase in the same steel. This is probably because the martensite phase has a lot of plane defects such as block boundaries for the fast diffusion path of Cr element. © 2007 The Japan Institute of Metals.
  • 新家光雄; 赤堀俊和; 仲井正昭; 服部友一; 春日敏宏
    金属 77 (2) 128 - 134 0368-6337 2007
  • Toshikazu Akahori; Mitsuo Niinomi; Masaaki Nakai
    Key Eng. Mater. TRANS TECH PUBLICATIONS LTD 352 297 - 300 1013-9826 2007 [Refereed]
     
    Titanium and its alloys have been widely used as biomaterials for hard tissue replacements because of their excellent mechanical properties and biocompatibility. However, the bonding between their surfaces and bone is not enough after implantation. The bioactive surface modification such as a hydroxyapatite (HAp) coating on their surfaces has been investigated. Recently, a simple method for forming HAp layer on the surfaces of titanium and its alloys has been developed. This method is called as alkaline treatment process. In this method, HAp deposits on the surfaces of titanium and its alloys by dipping into simulated body fluid (SBF) after an alkaline solution treatment that is followed by a baking treatment (alkaline treatment). This process is applicable to newly developed beta-type Ti-29Nb-13Ta-4.6Zr alloy (TNTZ) for biomedical applications achieving bioactive HAp modification. In this study, the morphology of the HAp layer formed on the surface of TNTZ was investigated after various alkaline treatments followed by dipping in SBF. The formability of HAp on the surface of TNTZ was then discussed. The formability of HAp on TNTZ is much lower than that of commercially pure Ti, Ti-6Al-4V ELI and Ti-15Mo-5Zr-3Al alloys, which are representative metallic biomaterials, The formability of HAp on TNTZ is improved by increasing the amount of Na in the sodium titanate gels formed during an alkaline solution treatment where the NaOH concentrations and the dipping time are over 5 M and 172.8 ks, respectively. The formability of HAp on TNTZ is considerably improved by dipping in a 5 M NaOH solution for 172.8 ks. This condition for alkaline solution treatment process is the most suitable for TNTZ.
  • Mitsuo Niinomi; Toshikazu Akahori; Masaaki Nakai; Hiroshi Ishikawa; Michiharu Ogawa
    Mater. Sci. Forum TRANS TECH PUBLICATIONS LTD 561-565 1471 - 1476 0255-5476 2007 
    The effect of oxygen content on aging behavior and invar characteristics of Ti-29Nb-13Ta-4.6.Zr (TNTZ) were investigated.The age hardening of TNTZ aged at 573 K and 723 K is enhanced with the oxygen content. The omega phase precipitates and grows from early stage of aging in TNTZ regardless of the oxygen content when aged at 573 K. The lath-like shape alpha phase precipitated in TNTZ aged at 723 K increases in size with the oxygen content. The elastic modulus increases with the oxygen content and aging. The omega phase increase the elastic modulus to a greater extent than the increase due to the alpha phase. The tensile strength increases with the oxygen content and aging, while the elongation decreases. TNTZ with oxygen content of 0.1 mass% exhibits invar-like characteristics through severe cold working. A higher oxygen content suppresses the invar-like characteristics of TNTZ.
  • Toshikazu Akahori; Mitsuo Niinomi; Masaaki Nakai; Michiharu Ogawa
    Mater. Sci. Forum TRANS TECH PUBLICATIONS LTD 561-565 1505 - 1508 0255-5476 2007 [Refereed]
     
    The tensile and plain fatigue properties of the P-type titanium alloy, Ti-29Nb-13Ta-4.6Zr alloy (TNTZ), which was subjected to various thermomechanical treatments. and cast TNTZ were investigated in order to judge its potential for biomedical and dental applications. The tensile strengths of TNTZ aged after solution treatment and that aged after cold rolling decrease with an increase in the aging temperature; however, their elongation exhibits an opposite trend. TNTZ composed of the omega phase or the alpha and a phases in the beta phase exhibits a tensile strength of about 1000 MPa or more. The tensile properties of the cast TNTZ with and without a surface reaction layer is are not significantly different, and are almost identcal to those of as-solutionized TNTZ. The plain fatigue strengths of TNTZ aged after solution treatment and those of TNTZ aged after cold rolling increase with the aging temperature. In particular, TNTZ aged at 723 K after cold rolling exhibits the highest fatigue strength in both the low- and high-cycle fatigue life regions. Further, the plain fatigue limit, which is about 770 MPa, is nearly equal to that of hot-rolled Ti-6Al-4V ELI alloy subjected to aging after solution treatment; Ti-6Al-4V ELI alloy is a representative alpha+beta-type titanium alloy for biomedical applications. The plain fatigue strength of cast TNTZ with a Surface reaction layer is considerably less than that of the as-cold-rolled and as-solutionized TNTZ. Consequently, in the low-fatigue life region, the fatigue crack easily Occurs at the surface reaction layer, which is brittle, and in the high-Fatigue life region, the fatigue crack occurs at the sites of casting defects (shrinkage). The fatigue limits range from 180 MPa to 200 MPa.
  • M. Nakai; M. Niinomi; T. Akahori; N. Ohtsu; H. Nishimura; H. Toda; H. Fukui; M. Ogawa
    Mater. Sci. Forum TRANS TECH PUBLICATIONS LTD 561-565 1509 - 1512 0255-5476 2007 
    The surface of Ti-29Nb-13Ta-4.6Zr (TNTZ) subjected to gas nitriding at 1023-1223 K was investigated in comparison with the conventional biomedical titanium alloy, Ti-6Al-4V ELI (Ti64). After gas nitriding, the microstructures near the surface of these alloys were observed by optical microscopy, X-ray diffraction, Auger electron spectroscopy, and X-ray photoelectron spectroscopy. In both alloys, two titanium nitrides (TiN and Ti2N) are formed and the a phase precipitated by gas nitriding. Furthermore, oxygen impurity in the gas nitriding atmosphere reacts with the titanium nitrides; thus, TiO2 is formed at the outermost titanium nitride layer. The surface hardening was also evaluated by Vickers hardness measurement. The Vickers hardness near the surface of TNTZ and Ti64 increases significantly by gas nitriding.
  • M. Nakai; K. Nagai; Y. Murata; M. Morinaga
    CORROSION SCIENCE PERGAMON-ELSEVIER SCIENCE LTD 48 (11) 3869 - 3885 0010-938X 2006/11 
    Hydrogen effect on high-temperature steam oxidation resistance was investigated using an Fe10%Cr-0.08%C ternary ferritic steel. In order to suppress hydrogen dissolution during steam oxidation, the steel was pre-oxidized in air at 923 K before exposure to steam. A thin oxide layer formed by the pre-oxidation was identified as Cr2O3 With containing a small amount of Fe2O3. This oxide layer worked to lower the oxidation rate in steam at 923 K. However, such a beneficial pre-oxidation effect disappeared when the specimen was exposed to steam for a long time, and nodular-like oxides were formed on the pre-oxidized specimen. There was a clear resemblance in both the chemical composition and the layer structure between the nodular-like oxides and the oxide scale usually formed during steam oxidation. As hydrogen diffusivity was much higher in such an oxide scale than in Cr2O3, hydrogen could dissolve in the nodular-like oxides readily during steam oxidation. Then, hydrogen-accelerated oxidation progressed even on the pre-oxidized specimen. (c) 2006 Elsevier Ltd. All rights reserved.
  • Y. Murata; M. Nakai; K. Nagai; M. Morinaga; Y. Sasaki; R. Hashizume
    Mater. Sci. Forum 522-523 147 - 154 2006/08 [Refereed]
  • K. Nagai; M. Nakai; T. Kunieda; Y. Murata; M. Morinaga; S. Matsuda; M. Kanno
    Mater. Sci. Forum 522-523 197 - 203 2006/08 [Refereed]
  • M. Niinomi; T. Akahori; M. Nakai; N. Ohtsu
    Proceedings of Materials Science and Technology Conference and Exhibition 2006 (MS&T’06) ASM INTERNATIONAL 141 - 161 2006 
    Ti-29Nb-13Ta-4.6Zr, referred to as TNTZ, and Ti-6Al-4V ELI were subjected to gas minding or oxidation process as comparison in order to harden their surface and improve their wear resistances. The friction wear tests were carried out on the nitrided or oxidized TNTZ and Ti-6Al-4V ELI in air and a simulated body fluid-Ringer's solution. The wear losses in the minded or oxidized TNTZ and Ti-6Al-4V ELI in Ringer's solution are lower than those in TNTZ and Ti-6Al-4V ELI without mtriding or oxidizing.
  • Dependence of High-Temperature Steam Oxidation Resistance on the Stability of the Chromium Sulfide in High-Chromium Heat-Resistant Steels
    M. Nakai; Y. Murata; M. Morinaga; R. Hashizume
    Proc. 4th Int. Conf. on Advances in Materials Technology for Fossil Power Plants, Oct. 2004, Hilton Head Island, South Carolina, USA 420 - 427 2005
  • M Nakai; K Nagai; Y Murata; M Morinaga; S Matsuda; M Kanno
    MATERIALS TRANSACTIONS JAPAN INST METALS 46 (1) 69 - 73 1345-9678 2005/01 
    The amount of hydrogen dissolved into Fe-10Cr-0.08C-0 similar to 0.03S (mass%) steels during the steam oxidation at 923 K was measured by thermal desorption spectroscopy (TDS). The amount of dissolved hydrogen was found to be dependent largely on the steam oxidation resistance of the steels. In other words, it was much smaller in the sulfur-doped steels with good oxidation resistance than in the sulfur-free steels with poor oxidation resistance. Thus, we suggest that the hydrogen dissolution is one of the most important factors to understand the steam oxidation resistance of the steels.
  • M Nakai; K Nagai; Y Murata; M Morinaga; S Matsuda; M Kanno
    ISIJ INTERNATIONAL IRON STEEL INST JAPAN KEIDANREN KAIKAN 45 (7) 1066 - 1072 0915-1559 2005 
    The high-temperature oxidation in both air and steam was examined experimentally with pure iron and a Fe-10Cr-0.08C (mass%) ternary ferritic steel. In case of pure iron, the thickness of the oxide scale formed in steam at 923 K for 360 ks was comparable to that of the scale formed in air. On the other hand, in case of the ternary ferritic steel, the oxide scale formed was much thicker in steam than in air. Thus, the oxidation rate was nearly independent of the air and the steam atmosphere for pure iron, but was dependent for the ternary ferritic steel. In the present study, this difference was investigated from a viewpoint of the hydrogen dissolution in the oxide scale during the steam oxidation. The amount of dissolved hydrogen was measured using a thermal desorption spectroscopy (TDS). It was found that the amount of the dissolved hydrogen was much larger in the ternary ferritic steel than in pure iron. Also, it was shown that the hydrogen dissolution in the ternary ferritic steel was related to the presence of (Fe,Cr)(3)O-4 in the oxide scale. The defect structure in this chromium-rich oxide was modified by hydrogen dissolution, so that the ionic diffusion could be enhanced in it, resulting in the more accelerated oxidation rate in steam.
  • T Kunieda; M Nakai; Y Murata; T Koyama; M Morinaga
    ISIJ INTERNATIONAL IRON STEEL INST JAPAN KEIDANREN KAIKAN 45 (12) 1909 - 1914 0915-1559 2005 
    The system free energy was estimated for the martensite phase of an Fe-Cr-C ternary alloy. The system free energy of the martensite phase is defined as, G(SYS)=G(0)+E-Str+E-Surf, where G(0) is the chemical free energy, E-Surf is the interfacial energy for the boundaries in the martensite microstructure, and E-str is the elastic strain energy due to the dislocations in the martensite phase. From the experimental results on SEM/EBSD, the interfacial energy was estimated to be 0.05 J/mol for the prior austenite boundary, 0.11 J/mol for the martensite packet boundary and 0.32 J/mol for both the martensite block and the lath boundaries in the asquenched specimen. The total decrement in the interfacial energy accompanying annealing at 873 K for 100 h after quenching was estimated to be about 0.1 J/mol. Also, the elastic strain energy of the asquenched specimen was estimated to be 7.1 J/mol. The total microstructural energy of the martensite phase was about 10J/mol, which operates as a driving force for the microstructure evolution, e.g., recovery of dislocations and the coarsening of the sub-structures such as martensite-packet, -block and -lath.
  • M Nakai; Y Murata; M Morinaga; Y Sasaki
    MATERIALS TRANSACTIONS JAPAN INST METALS 45 (3) 865 - 869 1345-9678 2004/03 
    The presence of sulfur (S) at an impurity level in high chromium (Cr) ferritic steels improves remarkably high-temperature steam oxidation resistance. However. it still remains unknown which S state in the steels gives such a beneficial effect. There are two possible S states in the steels: one is the soluble S state in a solid solution of the steel, and the other is the precipitated S state which occurs through the sulfide formation or the S segregation in grain boundaries. Either state appears depending on the S content and the heat-treatment temperature. In this study in order to elucidate the effective S state, high-temperature steam oxidation resistance was investigated with high Cr ferritic steels, by changing the S states in them by proper heat treatments. As the result, it was found that the precipitated S state operated more effectively to the improvement of steam oxidation resistance, as compared to the soluble S state.
  • M Nakai; Y Murata; M Morinaga; R Hashizume
    MATERIALS TRANSACTIONS JAPAN INST METALS 44 (9) 1830 - 1838 1345-9678 2003/09 
    The dependence of steam oxidation resistance on the sulfur content has been investigated systematically in both terrific and austenitic steels. It is found that the presence of impurity S. being considered as a harmful element in the past, improves significantly the steam oxidation resistance of high Cr steels. However, such a beneficial S effect is not so remarkable in low Cr steels, indicating that the S effect is related strongly to the Cr content in the steels. However, in case of high Cr ferritic steels containing more than 0.3%Si. the S effect is still less remarkable. These results are probably caused by the difference in the affinity of S for Cr atom and for Si atom. Since S has a strong affinity for Cr, Cr is enriched in the vicinity of the segregated-Si on the specimen surface even after the steam oxidation test for a short time. The enriched Cr layer obstructs the formation of any island-like Fe oxides on the surface because of the easy formation of the passive Cr2O3 oxide layer on this area. On the other hand, Si segregates onto the iron surface faster than S, but a part of the segregated-Si on the surface is replaced by S. Therefore, it is considered that the formation of SiO2 is difficult in the case when the S content is too higher in the steel. As a result, the S effect does not appear so significantly in the Si-containing steels.
  • M Nakai; Y Murata; M Morinaga; R Hashizume; Y Sawaragi
    Mater. Sci. Forum TRANS TECH PUBLICATIONS LTD 426-432 1029 - 1034 0255-5476 2003 
    Microalloying effects of sulfur are investigated systematically on the steam oxidation resistance of austenitic steels and ferritic steels. It is found that the presence of S, about 50ppm, in the steels improves remarkably the steam oxidation resistance of both austenitic steels and high Cr ferritic steels. This result indicates that ferritic steels with excellent steam oxidation resistance can be designed and developed by just leaving S at an impurity level in them without detriment to the mechanical strength. However, the S effect is not so remarkable in low Cr ferritic steels as in high Cr ferritic steels. This fact implies that the S effect is related strongly to the stability of Cr2O3 in high temperature steam conditions.
  • Y Murata; M Morinaga; N Inagaki; M Nakai
    MATERIALS TRANSACTIONS JAPAN INST METALS 43 (5) 1258 - 1259 1345-9678 2002/05 
    Mass loss occurs in Cr2O3 when it is exposed to steam at 923 K for 0.5 Ms or 1.3 Ms. The presence of Satan impurity I eve I of 23 pp in in the oxide suppresses the mass loss by about a half. For example, for the 0.5 Ms exposure, the mass loss is about 0.055% in pure Cr2O3 but about 0.030% in S-doped Cr2O3. This result is related closely to our previous result that the existence of 50 ppm S in high Cr ferritic steels causes a tremendous improvement in the steam oxidation resistance at 923 K.
  • Role of an Impurity Element on Improvement in Steam Oxidation Resistance of High Cr Ferritic Steels
    Y. Murata; M. Morinaga; R. Hashizume; Y. Sawarag; M. Nakai
    Proc. 3rd Int. Conf. on Advances in Materials Technology for Fossil Power Plants, Apr. 2001, Swansea, Wales, UK 367 - 374 2001
  • K Nakatsuka; M Takagi; M Nakai; H Yukawa; M Morinaga
    JAPAN INSTITUTE OF METALS, PROCEEDINGS, VOL 12, (JIMIC-3), PTS 1 AND 2 JAPAN INST METALS 681 - 684 1999 
    Most hydrogen storage compounds consist of hydride forming elements. A, and hydride non-forming elements, B. From the DV-X alpha molecular orbital calculation, it is found that hydrogen interacts more strongly with B elements than A elements in every hydrogen storage compound, despite that there is a larger affinity of A elements for hydrogen than B elements in the binary metal-hydrogen system. Also, it is shown that the A/B compositional ratio of hydrogen storage compounds is understood in terms of a simple parameter, 2 Bo(A-B) / [Bo(A-A)+Bo(B-B)], where the Bo(A-B), Bo(A-A) and the Bo(B-B) are the bond strengths between atoms given in the parentheses. This parameter resembles the ordering energy parameter, Omega(AB) (=V-AB- 1/2(V-AA+V-BB)), which controls the order-disorder phase transformation in alloys.

Books etc

  • チタンの基礎と応用（新家光雄, 池田勝彦, 成島尚之, 中野貴由, 細田秀樹 編著）
    新家光雄; 仲井正昭 (Contributor7.1節 溶解・鋳造)内田老鶴圃 2023/03
  • Novel Structured Metallic and Inorganic Materials (Edited by Y. Setsuhara, T. Kamiya and S. Yamaura)
    M. Niinomi; M. Nakai (Joint work(Chapter 30) Low-Young's-modulus materials for bio-medical applications)Springer 2019
  • Novel Structured Metallic and Inorganic Materials (Edited by Y. Setsuhara, T. Kamiya and S. Yamaura)
    M. Niinomi; M. Nakai (Joint work(Chapter 3) Ti-based biomedical alloys)Springer 2019
  • Novel Structured Metallic and Inorganic Materials (Edited by Y. Setsuhara, T. Kamiya and S. Yamaura)
    M. Nakai; M. Niinomi (Joint work(Chapter 26) Mechanical property of bio-medical materials)Springer 2019
  • Interface Oral Health Science 2016, Innovative Research on Biosis-Abiosis Intelligent Interface (Edited by K. Sasaki, O. Suzuki and N. Takahashi)
    P.F. Santos; M. Niinomi; H.H. Liu; M. Nakai; K. Cho; T. Narushima; K. Ueda; N. Ohtsu; M. Hirano; Y. Itoh (Joint work(Chapter 19) Development and performance of low cost beta-type Ti-based alloys for biomedical applications using Mn additions)Springer 2016/12
  • Advances in Metallic Biomaterials: Processing and Applications
    M. Niinomi; T. Narushima; M. Nakai (Editor)Springer 2015
  • Advances in Metallic Biomaterials: Processing and Applications (Edited by M. Niinomi, T. Narushima and M. Nakai)
    M. Nakai; M. Niinomi (Joint work(Chapter 12) Dental Metallic Materials)Springer 2015
  • Advances in Metallic Biomaterials: Tissues, Materials and Biological Reactions
    M. Niinomi; T. Narushima; M. Nakai (Editor)Springer 2015
  • Interface Oral Health Science 2014-Innovative Research on Biosis-Abiosis Intelligent Interface (Edited by K. Sasaki, O. Suzuki and N. Takahashi)
    M. Nakai; M. Niinomi; K. Cho; K. Narita (Joint work(Chapter 7) Enhancing functionalities of metallic materials by controlling phase stability for use in orthopedic implants)Springer 2014/12
  • バイオマテリアル研究の最前線（成島尚之, 中野貴由編）
    仲井正昭; 新家光雄 (Joint work気孔にモノマー溶液を浸透させ，その場重合させて医療用ポリマーを充填した生体用多孔質チタンの開発―多孔質化と医療用ポリマー充填の両用による金属材料の低ヤング率化と機械的強度維持の可能性―)日本金属学会 2014/10
  • バイオマテリアル研究の最前線 (成島尚之, 中野貴由編)
    仲井正昭; 新家光雄 (Joint work脊椎固定器具用ヤング率可変型β型Ti-Cr合金におけるCr含有量の最適化―応力遮蔽とスプリングバックとを抑制する弾性率自己調整機能―)日本金属学会 2014/10 41-42
  • Advances in Biomaterials Science and Biomedical Applications (Edited by R. Pignatello)
    J.Hieda; M. Niinomi; M. Nakai; K. Cho (Joint work(Chapter 20)Dental materials)InTech 2013/03
  • Technological Advancements in Biomedicine for Healthcare Applications (Edited by J. Wu)
    M. Nakai; M. Niinomi (Joint work(Chapter 22) Recent progress in mechanically biocompatible titanium-based materials)IGI Global 2012/10
  • Integrated Biomaterials for Biomedical technology (Edited by M. Ramalingam, A. Tiwari, S. Ramakrishna and H. Kobayashi)
    M. Nakai; M. Niinomi (Joint work(Chapter 12) Metal-polymer hybrid biomaterials with high mechanical and biological compatibilities)Scrivener Publishing 2012/07
  • Frontiers in Materials Research (Edited by Y. Fujikawa, K. Nakajima and T. Sakurai)
    M. Nakai; M. Niinomi; T. Akahori ((Chapter 14) Mechanically multifunctional properties and microstructure of new beta type titanium alloy, Ti-29Nb-13Ta-4.6Zr, for biomedical applications)Springer 2008/07

Conference Activities & Talks

  • Effect of Mg addition on mechanical and corrosive properties of biodegradable Fe-Mn alloy fabricated by mechanical alloying and spark plasma sintering
    K. Ueki; R. Hirano; M. Nakai
    Biomaterials International 2023  2023/07
  • Wear properties of biomedical titanium alloys with dimple textured surface through laser processing  [Invited]
    Masaaki Nakai; Takeshi Iwasaki; Kosuke Ueki
    Thermec'2023  2023/07
  • Improvement of work-hardening behavior of Co-Cr-W-Ni alloy by adding Mn / Fe for balloon-expandable stents
    Kosuke Ueki; Kyosuke Ueda; Masaaki Nakai; Takayoshi Nakano; Takayuki Narushima
    Thermec'2023  2023/07
  • Heat treatment to fabricate beta-type titanium alloy rod with partially different Young’s modulus for spinal fixation applications
    Masaaki Nakai; Kengo Narita; Mitsuo Niinomi
    World Titanium Conference 2023 (Ti-2023)  2023/06
  • 生体用チタン合金の摩耗特性に及ぼすディンプル型マイクロテクスチャの影響
    仲井正昭; 岩﨑武士; 植木洸輔
    軽金属学会第144回春期大会  2023/05
  • 弾性率の異なるTi合金プレートで固定した家兎大腿骨に形成された仮骨の定量評価
    宮﨑大輔; ノルアイン ビンティ; アブドラー; 山本衛; 植木洸輔; 仲井正昭
    日本金属学会2023年春期（第172回）講演大会  2023/03
  • 骨治癒の進行に及ぼすチタンインプラントプレートの剛性の影響
    ノルアイン ビンティ アブドラー; 宮崎大輔; 山本衛; 植木洸輔; 仲井正昭
    日本金属学会2023年春期（第172回）講演大会  2023/03
  • 生体用Co-Cr-W-Ni合金におけるメカニカルミリング法と放電プラズマ焼結を用いた調和組織形成による機械的特性向上
    植木洸輔; 水谷祐太; 仲井正昭
    日本金属学会2023年春期（第172回）講演大会  2023/03
  • SUS316Lステンレス鋼積層造形板における結晶方位配向と力学的特性に及ぼす造形条件の影響
    佐脇凜; 黒須信吾; 南部智憲; 植木洸輔; 仲井正昭
    日本鋳造工学会関西支部令和4年度秋季支部講演大会  2022/12
  • 窒化真空複合処理による医療用チタン合金の硬化膜の形成
    濱遼; 植木洸輔; 仲井正昭
    日本鋳造工学会関西支部令和4年度秋季支部講演大会  2022/12
  • さらなる低ヤング率を目指した生体用チタン合金開発の取り組み
    仲井正昭
    国際連携を見据えたマグネシウム・チタン若手研究会（軽金属学会国際交流委員会）  2022/11
  • Ti-6Al-4V合金の線形摩擦接合体のcold-dwell疲労特性
    趙艶華; 青木祥宏; 潮田浩作; 藤井英俊; 仲井正昭
    日本金属学会2022年秋期（第171回）講演大会  2022/09
  • 高濃度Taを含有するTi合金インゴット内部のTa濃度分布と局所的ヤング率
    大田尚輝; 植木洸輔; 仲井正昭
    日本金属学会2022年秋期（第171回）講演大会  2022/09
  • 骨治癒時の仮骨形成パターンに及ぼすインプラントプレートの剛性の影響
    ノルアイン ビンティ アブドラ―; 宮崎大輔; 山本衛; 植木洸輔; 仲井 正昭
    日本金属学会2022年秋期（第171回）講演大会  2022/09
  • 生体用Co-Cr-W-Ni合金におけるFe添加が機械的特性および耐食性に与える影響
    肥田輝; 植木洸輔; 上田恭介; 成島尚之; 仲井正昭
    日本金属学会2022年秋期（第171回）講演大会  2022/09
  • Effects of elastic modulus differences between titanium alloys and bone on bone formation during early stage of healing
    Norain Binti Abdullah; Daisuke Miyazaki; Ei Yamamoto; Kosuke Ueki; Masaaki Nakai
    第61回日本生体医工学会大会2022  2022/06
  • Effect of dimple texture on wear behaviors of β-type Ti-Nb-Ta-Zr and (α+β)-type Ti-6Al-4V ELI alloys in contact with zirconia for biomedical applications
    Masaaki Nakai
    2nd International Symposium on Light Alloys and Composite Materials (2nd UHAKS)  2022/03
  • 高濃度Taを含有するTi合金の溶解・凝固特性
    大田尚輝; 植木洸輔; 仲井正昭
    日本金属学会2022年春期（第170回）大会  2022/03
  • 初期治癒段階における骨形成に及ぼすインプラントプレートと骨との弾性率差の影響
    ノルアイン ビンティ アブドラー; 宮崎大輔; 山本衛; 植木洸輔; 仲井正昭
    日本金属学会2022年春期（第170回）大会  2022/03
  • メカニカルアロイングおよび放電プラズマ焼結によって作製したFe-Mn-Mg合金の相変態挙動と機械的および腐食特性
    植木洸輔; 平野涼; 仲井正昭
    日本金属学会2022年春期（第170回）大会  2022/03
  • Effects of titanium plate fixation on callus formation during early stage of bone healing
    Norain Binti Abdullah; Daisuke Miyazaki; Masaaki Nakai; Kosuke Ueki; Ei Yamamoto
    第4回日本金属学会第７分野講演会  2021/12
  • 医療用β型チタン合金の化学組成と力学的機能
    仲井正昭
    日本鉄鋼協会シンポジウム（良好な地球環境を継続的に維持するためのチタンとその合金の開発自主フォーラム）「チタン合金の相変態に関する研究動向」  2021/09
  • ヤング率可変型チタン合金の力学的特性とその改善
    仲井正昭
    軽金属学会第139回秋期大会  2020/11
  • MnおよびSiを添加したステント用Co-Cr合金の微細組織と機械的特性  [Not invited]
    柳原創; 植木洸輔; 上田恭介; 仲井正昭; 中野貴由; 成島尚之
    日本金属学会2020年秋期（第167回）大会  2020/09
  • 航空機用チタン合金摩擦攪拌接合継手の高疲労強度化のための組織制御技術の開発
    仲井正昭; 新家光雄; 藤井英俊; 森貞好昭; 劉恢弘
    大阪大学接合科学研究所第17回産学連携シンポジウム  2020/06
  • 生体用Co-Cr-W-Ni合金における加工熱処理プロセスによるバイモーダル組織形成と機械的特性評価
    平野涼; 植木洸輔; 成島尚之; 仲井正昭
    日本金属学会2020年春期（第166回）大会  2020/03
  • 選択的レーザー溶融法によって作製したTi-6Al-4V合金製六角柱格子構造体の変形挙動の解明  [Not invited]
    金泰可; 仲井正昭; 植木洸輔; 宮本陸; 坂田誠一郎; 京極秀樹
    日本鋳造工学会関西支部令和元年度秋季支部講演大会  2019/11
  • Grain refinement and mechanical properties of Co-Cr-W-Ni alloys used in stents  [Not invited]
    Soh Yanagihara; Kosuke Ueki; Kyosuke Ueda; Masaaki Nakai; Takayoshi Nakano; Takayuki Narushima
    The 4th International Symposium on Creation of Life Innovation Materials for Interdisciplinary and International Researcher Development (iLIM-4)  2019/10
  • ステント用Co-Cr-W-Ni 合金の結晶粒粒微細化と機械的特性  [Not invited]
    柳原創; 植木洸輔; 上田恭介; 仲井正昭; 中野貴由; 成島尚之
    2019年度東北大学金属材料研究所共同研究ワークショップ・日本バイオマテリアル学会東北ブロック講演会「バイオマテリアル研究を牽引する研究者との対話」  2019/10
  • 生体用Co-Cr-W-Ni合金における静的再結晶・低温熱処理プロセスによる強度・延性の向上  [Not invited]
    植木洸輔; 柳原創; 上田恭介; 仲井正昭; 中野貴由; 成島尚之
    日本金属学会2019年秋期（第165回）大会  2019/09
  • Effect of Laser Nitriding Process Repetition on Surface Hardening of Ti-6Al-4V ELI  [Not invited]
    Fatin Nabilah; Binti Sapari; 仲井正昭; 植木洸輔; 瀧口功大; 大津直史
    日本金属学会2019年秋期（第165回）大会  2019/09
  • SLMを用いて作製したTi-6Al-4V合金三次元格子構造体の変形挙動と特性  [Not invited]
    金泰可; 仲井正昭; 植木洸輔; 宮本陸; 坂田誠一郎; 京極秀樹
    日本金属学会2019年秋期（第165回）大会  2019/09
  • Effects of Young's modulus difference of titanium alloys and bone on bone formation  [Not invited]
    Norain Binti Abdullah; 仲井 正昭; 植木洸輔; 川村勇樹; 山本衛; 新家光雄
    日本金属学会2019年秋期（第165回）大会  2019/09
  • Fatigue properties of beta-type Ti-Cr alloy with changeable Young's modulus  [Not invited]
    Masaaki Nakai; Mitsuo Niinomi
    The 14th World Conference on Titanium (Ti-2019)  2019/06
  • Effect of Titanium Plate Fixation on Bone Healing  [Not invited]
    Norain Binti Abdullah; Masaaki Nakai; Yuki Kawamura; Ei Yamamoto; Mitsuo Niinomi
    The 14th World Conference on Titanium (Ti-2019)  2019/06
  • Quantitative relationship between microstructural factors and fatigue life of Ti-5Al-2Sn-2Zr-4Cr-4 Mo (Ti-17) fabricated using a 1500-ton forging simulator  [Not invited]
    M. Niinomi; T. Akahori; M. Nakai; Y. Koizumi; A. Chiba; T. Nakano; T. Kakeshita; Y. Yamabe-Mitarai; S. Kuroda; N. Motohashi; Y. Itsumi; T. Choda
    The 14th World Conference on Titanium (Ti-2019)  2019/06
  • The Deformation Behavior of Oxygen-Modified Ti-29Nb-13Ta-4.6Zr(wt.%)  [Not invited]
    V. Khademi; H.H. Liu; M. Nakai; M. Niinomi; C.J. Boehlert
    The 14th World Conference on Titanium (Ti-2019)  2019/06
  • 画像認識技術を用いたα＋β型チタン合金中におけるβ粒界の自動検出  [Not invited]
    中川暁; 仲井正昭
    軽金属学会第136回春期大会  2019/05
  • 共振式疲労試験法による生体用β型チタン合金の疲労特性の評価  [Not invited]
    長峯昂平; 仲井正昭
    軽金属学会第136回春期大会  2019/05
  • Application of atmospheric-pressure plasma treatment to coat Ti-alloy orthodontic wire with white oxide layer  [Not invited]
    Naho Mitsuishi; Eri Miura-Fujiwara; Motoko Yamada; Tadachika Chiba; Hisashi Sato; Yoshimi Watanabe; Michiko Ito; Seigo Takashima; Masaaki Nakai; Toshikazu Akahori; Masaki Tanaka; Mitsuo Niinomi; Tsutomu Takeuchi
    ISPlasma2019  2019/03
  • SLMを用いて作製したTi-6Al-4V合金三次元格子構造体の特性評価  [Not invited]
    金泰可; 仲井正昭; 坂田誠一郎; 京極秀樹
    日本金属学会2019年春期（第164回）大会  2019/03
  • Effect of titanium plate fixation on bone formation during healing period  [Not invited]
    Norain Binti Abdullah; Masaaki Nakai; Yuki Kawamura; Ei Yamamoto; Mitsuo Niinomi
    日本金属学会2019年春期（第164回）大会  2019/03
  • Improvement of surface and internal strength of β titanium alloy by atmospheric heat treatment  [Not invited]
    Fatin Nabilah; binti Sapari; Masaaki Nakai
    日本金属学会2019年春期（第164回）大会  2019/03
  • 1500トン鍛造シミュレータで作製したTi-17合金の溶体化時効処理後の組織  [Invited]
    仲井正昭
    SIPシンポジウム―大型精密鍛造シミュレータを用いた革新的新鍛造プロセス開発と材料・プロセスデータベース構築  2018/12
  • 選択的レーザー溶融法により作製したインコネル三次元構造体の観察と弾性解析  [Not invited]
    金泰可; 仲井正昭; 坂田誠一郎; 京極秀樹
    日本鋳造工学会関西支部平成30年度秋季支部講演大会  2018/11
  • チタン合金摩擦攪拌接合継手の疲労特性とその熱処理による改善  [Invited]
    仲井正昭
    大阪大学接合科学研究所平成30年度共同研究成果発表会  2018/11
  • 生体用低弾性率チタン合金の特徴と生体組織との整合性  [Invited]
    仲井正昭; 山本衛; 新家光雄
    第45回日本臨床バイオメカニクス学会  2018/11
  • 生体用β型チタン合金の整形外科用インプラントへの応用  [Not invited]
    仲井正昭
    第1回日本金属学会第4分野講演会「金属系バイオマテリアルサイエンスの新展開（Ⅰ）」  2018/10
  • Role of oxygen in titanium alloys for biomedical applications  [Invited]
    Mitsuo Niinomi; Qiang Li; Toshikazu Akahori; Masaaki Nakai; Takayuki Nakano; Deng Pan
    The 9th International Conference on Advanced Materials Processing (ICAMP-9)  2018/09
  • 生体用Co-Cr-W-Ni合金における歪み誘起マルテンサイト変態発生挙動の結晶粒径依存性  [Not invited]
    植木洸輔; 上田恭介; 仲井正昭; 中野貴由; 成島尚之
    日本金属学会2018年秋期（第163回）大会  2018/09
  • 種々の温度にて鍛造した次世代航空機用Ti-17熱処理材のミクロ組織と機械的強度  [Not invited]
    田中沙季; 赤堀俊和; 新家光雄; 仲井正昭
    日本金属学会2018年秋期（第163回）大会  2018/09
  • 種々の温度にて鍛造したTi-17時効材のミクロ組織と力学的特性との関係  [Not invited]
    新家光雄; 赤堀俊和; 仲井正昭; 中野貴由
    日本金属学会2018年秋期（第163回）大会および日本鉄鋼協会第176回秋季講演大会（共同セッション）  2018/09
  • SLMを用いて作製した金属三次元格子構造体の観察と弾性解析  [Not invited]
    金泰可; 仲井正昭; 坂田誠一郎; 山本衛; 京極秀樹
    日本金属学会2018年秋期（第163回）大会  2018/09
  • Influence of Young's modulus difference of titanium alloys on bone healing  [Not invited]
    Norain Binti Abdullah; Masaaki Nakai; Yuki Kawamura; Ei Yamamoto; Mitsuo Niinomi
    日本金属学会2018年秋期（第163回）大会  2018/09
  • White oxide coating of β Ti-alloy orthodontic wire by atmospheric-pressure plasma treatment  [Not invited]
    N. Mitsuishi; E. Miura-Fujiwara; M. Yamada; M. Ito; T. Chiba; H. Sato; M. Nakai; T. Akahori; S. Takashima; Y. Watanabe; T. Takeuchi; M. Niinomi
    15th International Symposium on Functionally Graded Materials (ISFGMs2018)  2018/08
  • Fatigue strength of beta-type Ti-12Cr alloy under solutionized condition for biomedical applications  [Invited]
    M. Nakai; M. Niinomi; H.H. Liu
    THERMEC'2018  2018/07
  • Development of biomedical beta-titanium alloys with deformation-induced changeable elastic modulus  [Invited]
    M. Nakai
    1st International Symposium on Light Alloys and Composite Materials (ISLAC'18)  2018/03
  • 生体用としてのβ型Ti-Nb合金の力学的機能性に及ぼす酸素の影響  [Not invited]
    新家光雄; Qiang Li; Dong Ma; Deng Pan; 仲井正昭; 小泉雄一郎; 魏代修; 千葉晶彦; 赤堀俊和; 中野貴由; 掛下知行
    日本金属学会2018年春期（第162回）大会  2018/03
  • ステント用Co-Cr合金の塑性変形挙動に及ぼす結晶粒径の影響  [Not invited]
    植木洸輔; 上田恭介; 仲井正昭; 中野貴由; 成島尚之
    日本金属学会2018年春期（第162回）大会  2018/03
  • 生体用チタン合金のヤング率制御と合金開発  [Invited]
    仲井正昭; 新家光雄
    日本学術振興会鋳物第24委員会鋳造プロセス分科会第19回会議  2017/12
  • Effect of solution treatment and aging on fatigue strength of friction stir welded Ti-6Al-4V alloy butt joint  [Not invited]
    M. Nakai; M. Niinomi; H.H.Liu; H. Fujii
    3rd International Conference on Friction Based Processes (IOFP2017)  2017/11
  • 航空機用Ti-17合金時効材のミクロ組織と力学的特性  [Not invited]
    新家光雄; 赤堀俊和; 仲井正昭; 小泉雄一郎; 千葉晶彦; 掛下知行
    軽金属学会第133回秋期大会  2017/11
  • 医療用チタン合金間で生じる摩擦摩耗の特徴  [Invited]
    仲井正昭; 新家光雄; 李允碩
    日本真空学会機能薄膜部会 ナノ構造機能創成専門部会 第8回研究会  2017/11
  • Comparison of corrosion behaviors of β-type Ti29Nb13Ta4.6Zr alloys with α and α+β type titanium alloys  [Not invited]
    Burak Dikici; Mitsuo Niinomi; Mehmet Topuz; Hakan Yılmazer; Masaki Nakai
    2nd International Conference on Advanced Engineering Technologies (ICADET 2017)  2017/09
  • 種々の溶体化処理を施したTi-17時効材のミクロ組織と疲労寿命の関係  [Not invited]
    新家光雄; 赤堀俊和; 仲井正昭; 掛下知行
    日本金属学会2017年秋期（第161回）大会および日本鉄鋼協会第174回秋季講演大会（共同セッション）  2017/09
  • 生体用Co-Cr-Mo合金の熱処理による機械的特性変化  [Not invited]
    植木洸輔; 阿部舞; 上田恭介; 仲井正昭; 中野貴由; 成島尚之
    日本金属学会2017年秋期（第161回）大会  2017/09
  • Controlling mechanical property by deformation-induced omega phase in biomedical beta-titanium alloys  [Not invited]
    M. Nakai
    KIM-JIM symposium -Interplay between,phase transformation and deformation in advanced structural materials-  2017/09
  • Development of metallic biomaterials with changeable elastic modulus using deformation-induced phase transformation  [Invited]
    M. Nakai; M. Niinomi
    Japan-Korea International Symposium on Materials Science and Technology 2017 (JKMST2017)  2017/08
  • 生体用弾性率可変型チタン合金の化学組成最適化  [Invited]
    仲井正昭; 新家光雄
    第56回日本生体医工学会大会  2017/05
  • Silver/hydroxyapatite hybrid coatings on Ti‒6Al‒4V surfaces by sol-gel method  [Not invited]
    Burak Dikici; Serap Gungor Koc; Mehmet Topuz; Mitsuo Niinomi; Hakan Yilmazer; Masaaki Nakai
    20th International ESAFORM Conference on Material Forming (ESAFORM2017)  2017/04
  • 種々の溶体化時効処理を施したTi17鍛造材のミクロ組織と機械的特性との関係  [Not invited]
    新家光雄; 赤堀俊和; 仲井正昭; 掛下知行
    日本金属学会2017年春期（第160回）大会および日本鉄鋼協会第173回春季講演大会（共同セッション）  2017/03
  • ステント用Co-Cr合金の低温熱処理および塑性変形に伴う微細組織変化  [Not invited]
    植木洸輔; 仲井正昭; 上田恭介; 成島尚之
    日本金属学会2017年春期（第160回）大会  2017/03
  • Effect of additional elements on microstructures in biomedical beta Ti alloys containing Nb, Ta, Zr and O  [Not invited]
    T. Homma; A. Arafah; M. Nakai; M. Niinomi; H.D. Haley; M; P. Moody
    TMS2017 146th Annual Meeting & Exhibition  2017/02
  • 生体内環境での使用を想定した新たな金属材料の開発  [Invited]
    仲井正昭
    はりま産学交流会11月創造例会  2016/11
  • Preparation and characterization of Hydroxyapatite/Chitosan sol-gel coatings on TiAl4V alloys  [Not invited]
    S.G. Koc; B. Dikici; M. Topuz; H. Yılmazer; I. Ozdemir; M. Niinomi; M. Nakai
    The 6th International Conference on Advanced Materials and Systems (ICAMS2016)  2016/10
  • ラミネートろ紙を用いた銅の抗菌性評価方法  [Not invited]
    翠川裕; 仲井正昭; 新家光雄
    日本銅学会第56回講演大会  2016/10
  • Synthesis and Characterization of Sol-Gel Hydroxyapatite Coatings on the Beta Type Titanium Alloys: The Effect of Sintering Conditions  [Not invited]
    B. Dikici; M. Topuz; S. G. Koc; H. Yilmazer; M. Niinomi; M. Nakai
    3rd International Conference on Advanced Technology & Sciences (ICAT'16)  2016/09
  • 生体用弾性率可変型チタン合金の化学組成と弾性率変化  [Not invited]
    仲井正昭; 新家光雄
    日本実験力学会 2016年度年次講演会  2016/09
  • TNTZ合金における添加元素が時効組織に及ぼす効果  [Not invited]
    本間智之; アイヌル アラファ; 仲井正昭; 新家光雄
    日本金属学会2016年秋期（第159回）大会  2016/09
  • 生体用準安定β型Ti-29Nb-13Ta-4.6Zr合金におけるω相の安定性に及ぼす酸素の特異な影響  [Not invited]
    新家光雄; 赤堀俊和; 仲井正昭
    日本金属学会2016年秋期（第159回）大会  2016/09
  • Improvement of static and dynamic strength of a biomedical beta-type titanium alloy by adding oxygen  [Not invited]
    Mitsuo Niinomi; Masaaki Nakai; Huihong Liu; Shinya Obara
    The 9th Pacific Rim International Conference on Advanced Materials and Processing (PRICM9)  2016/08
  • Solid solution strengthening of Ti by Mg in sputtered film  [Not invited]
    M. Nakai; M. Niinomi; H.H. Liu; Y. Suzuki; K. Cho; J. Nakamura; K. Yoshimi
    The 9th Pacific Rim International Conference on Advanced Materials and Processing (PRICM9)  2016/08
  • Balanced mechanical properties of Co-Cr-Mo alloys processed by high-pressure torsion and subsequent short-time solution treatment and characterization of their microstructures  [Not invited]
    Murat Isik; Mitsuo Niinomi; Huihong Liu; Masaaki Nakai; Ken Cho; Zenji Horita; Takayuki Narushima
    日本金属学会2016年春期（第158回）大会  2016/03
  • Improved mechanical performance by Mo addition in a series of Ti-Mn alloys developed for biomedical applications  [Not invited]
    Pedro Fernandes Santos; Mitsuo Niinomi; Masaaki Nakai; Huihong Liu; Takayuki Narushima; Ken Cho
    日本金属学会2016年春期（第158回）大会  2016/03
  • Influence of solid-solution strengthening in fatigue strength of construct using Ti-29Nb-13Ta-4.6Zr alloys for spinal fixation device  [Not invited]
    Y.-S. Lee; M. Niinomi; M. Nakai; H.H. Liu
    日本金属学会2016年春期（第158回）大会  2016/03
  • チタン中でのマグネシウムの固溶強化能  [Not invited]
    仲井正昭; 新家光雄; 劉恢弘; 鈴木優子; 趙研; 吉見享祐; 中村純也
    日本金属学会2016年春期（第158回）大会  2016/03
  • 酸素添加による生体用β型チタン合金の高耐久化  [Not invited]
    新家光雄; 仲井正昭; 劉恢弘; 趙研; 小原慎也
    日本金属学会2016年春期（第158回）大会  2016/03
  • Investigation on abnormal deformation behaviors of biomedical oxygen-modified Ti-29Nb-13Ta-4.6Zr alloys  [Not invited]
    H.H. Liu; M. Niinomi; M. Nakai; X. Cong; K. Cho; C. Boehlert
    日本金属学会2016年春期（第158回）大会および日本鉄鋼協会第171回春季講演大会（共同セッション）  2016/03
  • サルモネラのH2S産生能を用いて新たな抗菌性検査法開発  [Not invited]
    翠川裕; 仲井正昭; 新家光雄
    第89回日本細菌学会総会  2016/03
  • Effect of heterogeneous α precipitation on mechanical properties of a β-type Ti-Nb-Ta-Zr alloy for biomedical applications  [Invited]
    M. Nakai; M. Niinomi; K. Narita
    24th International Symposium on Processing and Fabrication of Advanced Materials (PFAM XXIV)  2015/12
  • Effect of interstitial element oxygen on wear characteristics of Ti-29Nb-13Ta-4.6Zr alloys for biomedical applications  [Not invited]
    Y.-S. Lee; M. Niinomi; M. Nakai; H.H. Liu
    第14回日本金属学会東北支部研究発表大会  2015/12
  • Abnormal deformation behaviors of biomedical oxygen-added Ti-29Nb-13Ta-4.6Zr alloys  [Not invited]
    H.H Liu; M. Niinomi; M. Nakai; X. Cong
    第14回日本金属学会東北支部研究発表大会  2015/12
  • 食中毒菌サルモネラを用いた銅の抗菌性評価方法  [Not invited]
    翠川裕; 新家光雄; 仲井正昭
    日本銅学会第55回講演大会  2015/11
  • 新規インプラント導入と添付文書策定の問題点  [Not invited]
    織部一弥; 長谷川和宏; 成田健吾; 仲井正昭; 高久田和夫; 新家光雄
    第24 回日本脊椎インストゥルメンテーション学会  2015/11
  • 電気化学処理によるチタンおよびチタン合金への抗菌性と硬組織適合性の同時付与  [Not invited]
    堤祐介; 島袋将弥; 仲井正昭; 蘆田茉希; 陳鵬; 土居壽; 新家光雄; 塙隆夫
    第37回日本バイオマテリアル学会大会  2015/11
  • Wear properties of solid-solution-strengthened Ti-Nb-Ta-Zr-O alloys  [Not invited]
    Y.-S. Lee; M. Niinomi; M. Nakai; H.H. Liu
    第37回日本バイオマテリアル学会大会  2015/11
  • Abnormal deformation behaviors in oxygen-added Ti-29Nb-13Ta-4.6Zr alloys  [Not invited]
    H.H. Liu; M. Niinomi; M. Nakai; X. Cong
    第37回日本バイオマテリアル学会大会  2015/11
  • 高耐久性弾性率可変型チタン合金製脊椎固定器具の開発  [Not invited]
    仲井正昭; 新家光雄; 劉恢弘; 成田健吾; 祖山均; ?桑脩
    第37回日本バイオマテリアル学会大会  2015/11
  • 弾性率可変型チタン合金の開発  [Invited]
    仲井正昭; 新家光雄
    第42回日本臨床バイオメカニクス学会  2015/11
  • O含有量の異なるTi-29Nb-13Ta-4.6Zr (mass%) 合金の時効析出挙動に及ぼす添加元素の効果  [Not invited]
    アイヌル アラファ; 仲井正昭; 新家光雄; 本間智之
    軽金属学会第129回秋期大会  2015/11
  • 非平衡Ti-Mg合金の力学的性能  [Not invited]
    鈴木優子; 新家光雄; 仲井正昭; 劉恢弘; 趙研; 吉見享祐; 中村純也
    軽金属学会第129回秋期大会  2015/11
  • 生体用β型チタン合金の耐久性に及ぼす侵入型軽元素の影響  [Not invited]
    小原慎也; 新家光雄; 仲井正昭; 劉恢弘, 趙研
    軽金属学会第129回秋期大会  2015/11
  • Ti-6Al-4V合金摩擦攪拌接合継手におけるミクロ組織と力学的特性  [Not invited]
    石田悠; 新家光雄; 仲井正昭; 劉恢弘; 藤井英俊; 森貞好昭
    軽金属学会第129回秋期大会  2015/11
  • Mechanical performance of a series of novel Ti-Mn alloys with Mo addition designed as a biomaterial  [Not invited]
    P.F. Santos; M. Niinomi; H.H. Liu; M. Nakai; K. Cho
    軽金属学会第129回秋期大会  2015/11
  • Influence of solid-solution strengthening in wear characteristics of Ti-29Nb-13Ta-4.6Zr alloys for biomedical applications  [Not invited]
    Y.-S. Lee; M. Niinomi; M. Nakai; H.H. Liu
    軽金属学会第129回秋期大会  2015/11
  • Elucidation of deformation behaviors in biomedical metastable beta-type titanium alloys with oxygen addition  [Not invited]
    H.H. Liu; M. Niinomi; M. Nakai; X. Cong
    軽金属学会第129回秋期大会  2015/11
  • Mechanical properties of Co-Cr-Mo alloy processed using high-pressure torsion processing and a subsequent short-time solution treatment  [Not invited]
    M. Isik; M. Niinomi; H.H. Liu; M. Nakai; K. Cho; Z. Horita
    第130回東北大学金属材料研究所講演会  2015/11
  • Wear properties of solid-solution-strengthened TNTZ alloys with high oxygen content  [Not invited]
    Y.-S. Lee; M. Niinomi; M. Nakai; H.H. Liu
    第130回東北大学金属材料研究所講演会  2015/11
  • 非平衡プロセスを用いて作製した軽量Ti-Mg合金の力学的特性  [Not invited]
    鈴木優子; 新家光雄; 仲井正昭; 劉恢弘; 趙研; 吉見享祐; 中村純也
    第130回東北大学金属材料研究所講演会  2015/11
  • 摩擦攪拌接合を施したTi-6Al-4V合金におけるミクロ組織と力学的特性  [Not invited]
    石田悠; 新家光雄; 仲井正昭; 劉恢弘; 藤井英俊; 森貞好昭
    第130回東北大学金属材料研究所講演会  2015/11
  • 侵入型軽元素の添加による生体用β型チタン合金の疲労強度の改善  [Not invited]
    小原慎也; 新家光雄; 仲井正昭; 劉恢弘, 趙研
    第130回東北大学金属材料研究所講演会  2015/11
  • サルモネラ硫化水素産生を用いた新抗菌性検査  [Not invited]
    翠川裕; 仲井正昭; 新家光雄
    第68回日本細菌学会関西支部総会・学術講演会  2015/11
  • 酸素添加した生体用β型Ti-29Nb-13Ta-4.6Zr合金における特異変形挙動の解明  [Not invited]
    劉恢弘; 新家光雄; 仲井正昭; 叢欣
    日本歯科理工学会平成27年度秋期第66回学術講演会  2015/10
  • Improving mechanical properties of Co-Cr-Mo alloys by microstructural control via high-pressure torsion and short-time solution treatment  [Not invited]
    M. Isik; M. Niinomi; H.H. Liu; M. Nakai; K. Cho; Z. Horita
    日本歯科理工学会平成27年度秋期第66回学術講演会  2015/10
  • Ti-Mg合金薄膜におけるMg濃度とリン酸カルシウム形成能との関係  [Not invited]
    稗田純子; 新家光雄; 仲井正昭; 趙研
    精密工学会2015年度秋季大会  2015/09
  • 侵入型軽元素による生体用β型チタン合金の高耐久化  [Not invited]
    小原慎也; 新家光雄; 仲井正昭; 劉恢弘, 趙研
    日本金属学会2015年秋期（第157回）大会  2015/09
  • マグネトロンスパッタリング法を用いた軽量Ti-Mg合金の作製およびその機械的硬さの評価  [Not invited]
    鈴木優子; 新家光雄; 仲井正昭; 劉恢弘; 趙研; 吉見享祐; 中村純也
    日本金属学会2015年秋期（第157回）大会  2015/09
  • Microstructural evolution and mechanical properties of Co-Cr-Mo alloys subjected to high pressure torsion and short-time solution treatment  [Not invited]
    M. Isik; M. Niinomi; H.H. Liu; M. Nakai; K. Cho; Z. Horita
    日本金属学会2015年秋期（第157回）大会  2015/09
  • Analysis of deformation behaviors of beta-type biomedical Ti-29Nb-13Ta-4.6Zr alloy with oxygen addition  [Not invited]
    H.H. Liu; M. Niinomi; M. Nakai; X. Cong; K. Cho
    日本金属学会2015年秋期（第157回）大会  2015/09
  • 摩擦攪拌接合を施したTi-6Al-4V合金の力学的特性  [Not invited]
    石田悠; 新家光雄; 仲井正昭; 劉恢弘; 藤井英俊; 森貞好昭
    日本金属学会2015年秋期（第157回）大会および日本鉄鋼協会第170回秋季講演大会（共同セッション）  2015/09
  • Mechanical performance and microstructures of low cost Ti-Mn-Mo alloys for biomedical applications  [Not invited]
    Pedro Fernandes Santos; Mitsuo Niinomi; Huihong Liu; Masaaki Nakai; Ken Cho
    日本金属学会2015年秋期（第157回）大会および日本鉄鋼協会第170回秋季講演大会（共同セッション）  2015/09
  • 弾性率可変型Ti-12Cr合金の疲労特性  [Not invited]
    仲井正昭; 新家光雄; 劉恢弘; 塚原真宏; 遠所茂夫; 三坂佳孝
    日本金属学会2015年秋期（第157回）大会および日本鉄鋼協会第170回秋季講演大会（共同セッション）  2015/09
  • 熱処理および表面改質処理を施した生体用Ti-12Cr合金の力学的特性の変化  [Not invited]
    丹羽謙太郎; 赤堀俊和; 新家光雄; 仲井正昭
    日本金属学会2015年秋期（第157回）大会  2015/09
  • 溶液プロセスでTNTZ表面に形成したナノ構造酸化物層の生体活性化と引っ張り強度試験  [Not invited]
    高橋慧; 武末江莉; 稗田純子; 生駒俊之; 岡田清; 松下伸広; 黒田健介; 趙研; 仲井正昭; 新家光雄
    特異構造金属・無機融合高機能材料開発共同研究プロジェクト平成27年度生体・医療材料開発分野分科会  2015/08
  • 電気化学的表面処理によるチタン合金への抗菌性・硬組織適合性の同時付与  [Not invited]
    堤祐介; 島袋将弥; 蘆田茉希; 陳鵬; 土居壽; 塙隆夫; 仲井正昭; 新家光雄
    特異構造金属・無機融合高機能材料開発共同研究プロジェクト平成27年度生体・医療材料開発分野分科会  2015/08
  • 生体用α+β型およびβ型チタン合金の摩耗挙動の違い  [Not invited]
    仲井正昭; 新家光雄; 劉恢弘; 李允碩
    特異構造金属・無機融合高機能材料開発共同研究プロジェクト平成27年度生体・医療材料開発分野分科会  2015/08
  • Bending springback of biomedical beta-type titanium alloys for spinal fixation applications  [Not invited]
    M. Nakai; M. Niinomi; K. Cho; H.H. Liu; K. Narita
    Biomaterials International 2015  2015/06
  • Effect of oxygen solute on deformation behavior of a β-type Ti-Nb-Ta-Zr alloy  [Not invited]
    M. Nakai; M. Niinomi; H.H. Liu; X. Cong
    The 6th International Symposium on Advanced Materials Development and Integration of Novel Structured Metallic and Inorganic Materials (AMDI-6)  2015/06
  • 新たな生体用チタン合金の開発と脊椎固定器具への応用  [Invited]
    仲井正昭
    チタノミックス研究会平成27年度講演会  2015/06
  • 銅をモデルとしてサルモネラ硫化水素産生を用いた新抗菌性検査法  [Not invited]
    翠川裕; 仲井正昭; 新家光雄
    日本食品衛生学会第109回学術講演会  2015/05
  • 機械的表面改質処理を施した生体用チタン合金のミクロ組織と機械的強度  [Not invited]
    赤堀俊和; 仲井正昭; 新家光雄
    軽金属学会第128回春期大会  2015/05
  • Ti-29Nb-13Ta-4.6Zr合金の時効硬化挙動に及ぼすO添加の効果  [Not invited]
    アイヌルアラファ; 又吉勇介; 仲井正昭; 新家光雄; 本間智之
    軽金属学会第128回春期大会  2015/05
  • マグネトロンスパッタリング法を用いて作製したTi-Mg合金の機械的硬さの評価  [Not invited]
    鈴木優子; 新家光雄; 趙研; 仲井正昭; 劉恢弘
    軽金属学会第128回春期大会  2015/05
  • 酸素添加による生体用Ti-29Nb-13Ta-4.6Zr合金の疲労強度の改善  [Not invited]
    小原慎也; 新家光雄; 趙研; 仲井正昭; 劉恢弘
    軽金属学会第128回春期大会  2015/05
  • 摩擦攪拌接合を施したTi-6Al-4V合金におけるミクロ組織と引張特性  [Not invited]
    石田悠; 新家光雄; 仲井正昭; 趙研; 劉恢弘; 藤井英俊; 森貞好昭
    軽金属学会第128回春期大会  2015/05
  • Mechanical performance of Ti-Mn-Mo alloys for biomedical applications  [Not invited]
    P.F. Santos; M. Niinomi; K. Cho; M. Nakai; H.H. Liu
    軽金属学会第128回春期大会  2015/05
  • Wear characteristics of Ti-29Nb-13Ta-4.6Zr alloys having high oxygen content  [Not invited]
    Y.-S. Lee; M. Niinomi; M. Nakai; K. Cho; K. Narita
    軽金属学会第128回春期大会  2015/05
  • Optimization on chemical composition of Ti-Cr-O alloys for achieving significantly changeable Young's modulus and good mechanical properties for spinal fixation applications  [Not invited]
    H.H. Liu; M. Niinomi; M. Nakai; K. Cho; K. Narita
    軽金属学会第128回春期大会  2015/05
  • Osteoblast cell behavior on biomedical β-type titanium alloys  [Not invited]
    H. Yilmazer; M. Niinomi; K. Cho; M. Nakai; H.H. Liu; M. Sen; H. Shiku; T.Matsue
    軽金属学会第128回春期大会  2015/05
  • 生体用低コストβ型Ti-Mn合金の長期的な力学および生物学的生体適合性  [Not invited]
    趙研; 新家光雄; 仲井正昭; 劉恢弘; P.F. Santos; A.M. Liens; 池田勝彦
    軽金属学会第128回春期大会  2015/05
  • β型Ti-Nb-Ta-Zr合金の変形挙動に及ぼす固溶酸素の影響  [Not invited]
    仲井正昭; 新家光雄; 趙研; 劉恢弘, 叢欣
    軽金属学会第128回春期大会  2015/05
  • 脊椎固定器具用チタン合金の開発とその実用化に向けて  [Invited]
    仲井正昭; 新家光雄; 成田健吾
    日本材料学会・疲労部門委員会および生体医療材料部門委員会合同公開委員会  2015/05
  • Mechanical properties of low-cost β-type Ti-Mn alloys for biomedical applications fabricated by metal injection molding  [Not invited]
    P.F. Santos; M. Niinomi; K. Cho; M. Nakai; H.H. Liu; Y. Itoh; M. Ikeda
    粉体粉末冶金協会平成27年度春季大会（第115回講演大会）  2015/05
  • 大気中およびリンゲル液中における生体用チタン合金間の摩耗特性  [Not invited]
    仲井正昭; 新家光雄; 成田健吾; 趙研; 劉恢弘; 李允碩
    粉体粉末冶金協会平成27年度春季大会（第115回講演大会）  2015/05
  • In situ synchrotron X-ray diffraction of stress-induced martensitic transformation in NiTi and metastable beta Ti-24Nb-X alloys  [Not invited]
    L. Heraud; P. Castany; M. Niinomi; M. Nakai; H.H. Liu; K. Cho; T. Gloriant
    第129回東北大学金属材料研究所講演会  2015/05
  • Ti-6Al-4V合金摩擦攪拌接合継手の力学的特性  [Not invited]
    石田悠; 新家光雄; 仲井正昭; 劉恢弘; 藤井英俊; 森貞好昭
    第129回東北大学金属材料研究所講演会  2015/05
  • β型Ti-29Nb-13Ta-4.6Zr合金の疲労強度に及ぼす酸素添加の影響  [Not invited]
    小原慎也; 新家光雄; 仲井正昭; 劉恢弘, 趙研
    第129回東北大学金属材料研究所講演会  2015/05
  • マグネトロンスパッタリング法を用いて作製したTi-Mg合金の機械的硬さに及ぼすMg含有量の影響  [Not invited]
    鈴木優子; 新家光雄; 仲井正昭; 劉恢弘; 趙研; 吉見享祐; 中村純也
    第129回東北大学金属材料研究所講演会  2015/05
  • Controlling phase transformation and grain refinement of Co-Cr-Mo alloy for enhancing its mechanical properties using a high-pressure torsion processing  [Not invited]
    M. Isik; M. Niinomi; H.H. Liu; M. Nakai; K. Cho; Z. Horita
    第129回東北大学金属材料研究所講演会  2015/05
  • Mechanical properties of newly developed β-type Ti-Mn-Mo alloys for biomedical applications  [Not invited]
    P.F. Santos; M. Niinomi; K. Cho; H. Liu; M. Nakai
    第129回東北大学金属材料研究所講演会  2015/05
  • Enhanced biocompatibility of biomedical β-type titanium alloys subjected to severe plastic deformation  [Not invited]
    H. Yilmazer; M. Niinomi; K. Cho; M. Nakai; H.H. Liu
    第129回東北大学金属材料研究所講演会  2015/05
  • β-type titanium alloy possessing remarkably changeable Young's modulus and good mechanical biocompatibility for spinal fixation surgery  [Not invited]
    Huihong Liu; Mitsuo Niinomi; Masaaki Nakai; Ken Cho; Kengo Narita
    第129回東北大学金属材料研究所講演会  2015/05
  • Formation and hardening behavior of L10-type ordered beta prime phase in as-solutionized dental Ag-Pd-Au-Cu alloys  [Not invited]
    H.H. Liu; M. Niinomi; M. Nakai; K. Cho; H. Fukui
    日本歯科理工学会平成27年度春期第65回学術講演会  2015/04
  • Osteoblast attachment on nanostructured beta-type titanium alloys subjected to severe plastic deformation  [Not invited]
    H. Yilmazer; M. Niinomi; K. Cho; M. Nakai; H.H. Liu; Y. Todaka; D. Burak; M. Sen; H. Shiku; T. Matsue
    日本歯科理工学会平成27年度春期第65回学術講演会  2015/04
  • Evolution of microstructure and enhancement of mechanical properties of Co-Cr-Mo alloys by high-pressure torsion processing  [Not invited]
    M. Isik; M. Niinomi; K. Cho; M. Nakai; H.H. Liu; Z. Horita
    日本歯科理工学会平成27年度春期第65回学術講演会  2015/04
  • 変形機構制御によるMo添加β型Ti-Mn系合金の強度−延性バランスの改善  [Not invited]
    日本金属学会2015年春秋期（第156回）大会および日本鉄鋼協会第169回春季講演大会（共同セッション）  2015
  • 高周波マグネトロンスパッタリング法を用いたバルクTi-Mg合金の作製  [Not invited]
    日本金属学会2015年春期（第156回）大会  2015
  • 生体用β型チタン合金の疲労強度に及ぼす酸素添加の影響  [Not invited]
    日本金属学会2015年春期（第156回）大会  2015
  • 摩擦攪拌接合したTi-6Al-4V合金における接合部の硬さとミクロ組織  [Not invited]
    日本金属学会2015年春期（第156回）大会  2015
  • 生体用β型チタン合金の無析出帯および粒界α相が力学的特性に与える影響  [Not invited]
    日本金属学会2015年春期（第156回）大会  2015
  • Cellular behavior of nanostructured β-type Ti-29Nb-13Ta-4.6Zr through severe plastic deformation  [Not invited]
    日本金属学会2015年春期（第156回）大会  2015
  • Improvement of mechanical properties of Co-Cr-Mo alloys by microstructural control through high-pressure torsion processing  [Not invited]
    日本金属学会2015年春期（第156回）大会  2015
  • Mechanical properties of new Ti-Mn-Mo alloys for use in biomedical applications  [Not invited]
    日本金属学会2015年春期（第156回）大会  2015
  • Frictional wear behavior of Ti-29Nb-13Ta-4.6Zr alloys with different amount of oxygen for biomedical applications  [Not invited]
    日本金属学会2015年春期（第156回）大会  2015
  • Remarkably changeable Young's modulus with good mechanical biocompatibility obtained in beta-type titanium alloys for spinal fixation applications  [Not invited]
    日本金属学会2015年春期（第156回）大会  2015
  • 脊椎外科におけるインプラント治療と金属材料  [Not invited]
    日本金属学会2015年春期（第156回）大会  2015
  • 固溶酸素を利用した生体用β型Ti-Cr合金の機能改善  [Not invited]
    日本金属学会チタン製造プロセスと材料機能研究会第1回講演会  2015
  • 脊椎疾患の治療に用いられるインプラント材料の開発  [Not invited]
    日本材料学会第38回生体・医療材料部門委員会  2015
  • レーザー積層造形法を用いて作製したTi/ZrおよびTNTZ/Zr複合材の開発  [Not invited]
    特異構造金属・無機融合高機能材料開発共同研究プロジェクト平成26年度生体・医療材料開発分野分科会  2015
  • TNTZ合金上でのバイオアクティブ界面形成とIn-vitroおよびIn-vivo評価  [Not invited]
    特異構造金属・無機融合高機能材料開発共同研究プロジェクト平成26年度生体・医療材料開発分野分科会  2015
  • マイクロアーク酸化処理による抗菌性チタン表面の形成  [Not invited]
    特異構造金属・無機融合高機能材料開発共同研究プロジェクト平成26年度生体・医療材料開発分野分科会  2015
  • 低弾性率チタン合金を用いた脊椎固定器具の開発に向けて  [Not invited]
    特異構造金属・無機融合高機能材料開発共同研究プロジェクト平成26年度生体・医療材料開発分野分科会  2015
  • A novel β-type titanium alloy with changeable Young's modulus and large elongation-to-failure for spinal fixation devices  [Not invited]
    第13回日本金属学会東北支部研究発表大会  2014
  • 摩擦攪拌接合を施した航空機用チタン合金の疲労特性  [Not invited]
    大阪大学接合科学研究所東京セミナー「摩擦発熱現象を利用した低温プロセスによる接合/改質技術の高度化」  2014
  • Ti-29Nb-13Ta-4.6Zr (wt.%) 合金の時効処理挙動に及ぼすO添加の効果  [Not invited]
    日本金属学会・日本鉄鋼協会北陸信越支部平成26年度連合講演会  2014
  • Unique mechanical behavior of Ti-29Nb-13Ta-4.6Zr alloy containing oxygen  [Not invited]
    第128回東北大学金属材料研究所講演会  2014
  • Controlling microstructure of Co-Cr-Mo alloy for improving its mechanical biocompability through high-pressure torsion processing  [Not invited]
    第128回東北大学金属材料研究所講演会  2014
  • Microstructures and compressive behaviour of low-cost β-type Ti-Mn alloys produced by metal injection moulding  [Not invited]
    第128回東北大学金属材料研究所講演会  2014
  • Wear characteristics of Ti-29Nb-13Ta-4.6Zr alloys with different amount of interstitial element oxygen  [Not invited]
    第128回東北大学金属材料研究所講演会  2014
  • 低コスト生体用β型Ti-Mn合金の微細組織および疲労特性の影響  [Not invited]
    第128回東北大学金属材料研究所講演会  2014
  • A novel β-type titanium alloy with changeable Young's modulus and good ductility for spinal fixation devices  [Not invited]
    第128回東北大学金属材料研究所講演会  2014
  • Microstructures and hardness of Ti/Zr and TNTZ/Zr composite materials fabricated by selective laser melting process  [Not invited]
    The 5th International Symposium on Ad-vanced Materials Development and Inte-gration of Novel Structured Metallic and Inorganic Materials (AMDI-5) conjunction with 6th IBB Frontier Symposium  2014
  • Development for a spinal fixation rod with low-rigidity and high-durability  [Not invited]
    The 5th International Symposium on Ad-vanced Materials Development and Inte-gration of Novel Structured Metallic and Inorganic Materials (AMDI-5) conjunction with 6th IBB Frontier Symposium  2014
  • Nanostructured β-type titanium alloys: Mechanical and biological biocompatibility  [Not invited]
    Innovative Materials and Structure Technologies Metallurgical Engineering Conference (METECH'14)  2014
  • 高圧ねじり加工を用いたナノ組織化によるβ型チタン合金の高生物学的生体適合性化  [Not invited]
    第36回日本バイオマテリアル学会大会  2014
  • 脊椎固定器具用チタン合金の微細組織と曲げ特性  [Not invited]
    第36回日本バイオマテリアル学会大会  2014
  • 低コストβ型Ti-Mn-Mo合金の微細組織および力学的特性に及ぼすMoの影響  [Not invited]
    軽金属学会第127回秋期大会  2014
  • 生体用β型チタン合金製脊椎固定器具の耐久性向上に及ぼすキャビテーションピーニングの効果  [Not invited]
    軽金属学会第127回秋期大会  2014
  • Effect of polar extract of cocoa peels inhibitor on mechanical properties and microstructure of mild steel exposed in hydrocloric acid  [Not invited]
    The 3rd International Conference on Sustainable Technology Development (ICSTD2014)  2014
  • 医療用チタン合金の弾性率制御  [Not invited]
    日本金属学会・日本鉄鋼協会中国四国支部第120回金属物性研究会  2014
  • Evaluation of long-term mechanical and biological biocompatibility of low-cost β-type Ti-Mn alloys for biomedical applications  [Not invited]
    Materials Science and Technology 2014 Conference and Exhibition (MS&T'14)  2014
  • Development of low-cost high-strength β-type alloys using a metal injection molding  [Not invited]
    Materials Science and Technology 2014 Conference and Exhibition (MS&T'14)  2014
  • Strengthening behaviors of low-precious Ag-Pd-Au-Zn alloys for dental applications  [Not invited]
    Materials Science and Technology 2014 Conference and Exhibition (MS&T'14)  2014
  • 低弾性率β型チタン合金の実用化に向けた取り組み  [Not invited]
    東北大学金属材料研究所ワークショップおよび日本バイオマテリアル学会東北地域講演会「産学官連携による金属系バイオマテリアルの研究開発の最前線」  2014
  • Improvement of mechanical properties of biomedical Co-Cr-Mo alloy through microstructural control using a high-pressure torsion processing  [Not invited]
    日本歯科理工学会平成26年度秋期第64回学術講演会  2014
  • 金属粉末射出成形法により作製した低コストTi-Mn合金のミクロ組織および力学的特性  [Not invited]
    日本歯科理工学会平成26年度秋期第64回学術講演会  2014
  • Changeable Young's modulus with good ductility achieved in a β-type titanium alloy for spinal fixation applications  [Not invited]
    日本金属学会2014年秋期（第155回）大会および日本鉄鋼協会第168回秋季講演大会（共同セッション）  2014
  • キャビテーションピーニングを施したTi-29Nb-13Ta-4.6Zr合金製脊椎固定器具の耐久性  [Not invited]
    日本金属学会2014年秋期（第155回）大会および日本鉄鋼協会第168回秋季講演大会（共同セッション）  2014
  • レーザ積層造形法により作製したTi/ZrおよびTNTZ/Zr複合材の組織  [Not invited]
    日本金属学会2014年秋期（第155回）大会  2014
  • キャビテーションピーニング処理によるβ型チタン合金製脊椎固定器具の耐久性改善  [Not invited]
    日本金属学会2014年秋期（第155回）大会  2014
  • Deformation behavior of Ti-29Nb-13Ta-4.6Zr alloy containing oxygen  [Not invited]
    日本金属学会2014年秋期（第155回）大会  2014
  • Improvement of mechanical biocompatibility of Co-Cr-Mo alloy by grain refinement and controlling of microstructure using a high-pressure torsion processing  [Not invited]
    日本金属学会2014年秋期（第155回）大会  2014
  • Mechanical properties, microstructures and biocompatibility of low-cost β-type Ti-Mn alloys fabricated by CCLM and MIM methods  [Not invited]
    日本金属学会2014年秋期（第155回）大会  2014
  • Sliding wear behavior of Ti-29Nb-13Ta-4.6Zr alloys with different oxygen contents for biomedical applications  [Not invited]
    日本金属学会2014年秋期（第155回）大会  2014
  • 金属粉末射出成形法を用いて作製した低コストβ型Ti-Mn合金の冷間圧延による高強度化  [Not invited]
    日本金属学会2014年秋期（第155回）大会  2014
  • 表面硬化処理を施した生体用β型チタン合金製脊椎固定器具の圧縮疲労強度  [Not invited]
    日本機械学会2014年度年次大会  2014
  • Frictional wear behavior of Ti-29Nb-13Ta-4.6Zr alloys with different oxygen contents for biomedical applications  [Not invited]
    9th International Workshop on Biomaterials in Interface Science-Innovative Research for Biosis-Abiosis Intelligent Interface Summer Seminar 2014-  2014
  • Low-cost Ti-Mn alloys for use as biomaterials and its mechanical properties  [Not invited]
    材料フェスタ in 仙台  2014
  • Changeable Young's modulus with good ductility in a β-type Ti-Cr alloy used for spinal fixation devices  [Not invited]
    材料フェスタ in 仙台  2014
  • Deformation-induced phase transformations in β-type biomedical titanium alloys  [Not invited]
    International Conference on Martensitic Transformations 2014 (ICOMAT-2014)  2014
  • Effects of cavitation peening on mechanical properties of spinal rods prepared using titanium alloys  [Not invited]
    東北大学大学院工学研究科表面力学設計研究会  2014
  • Mechanical properties of newly developed low cost titanium alloys subjected to microstructural control for next generation aircrafts  [Not invited]
    AeroMat 2014 Conference & Exposition  2014
  • 金属粉末射出成形を用いて作製した低コスト高強度β型Ti-Mn合金における冷間圧延による飛躍的な機械的強度の向上  [Not invited]
    第127回東北大学金属材料研究所講演会  2014
  • Mechanical Biocompatibility of biomedical β-type titanium alloy subjected to high-pressure torsion after aging treatment  [Not invited]
    第127回東北大学金属材料研究所講演会  2014
  • Mechanical behaviour and microstructure of low-cost β-type Ti-Mn alloys produced by metal injection molding and cold crucible levitation melting methods  [Not invited]
    第127回東北大学金属材料研究所講演会  2014
  • Improvement of mechanical biocompability of Co-Cr-Mo alloy using a high-pressure torsion processing  [Not invited]
    第127回東北大学金属材料研究所講演会  2014
  • Changeable Young's modulus with good ductility in β-type titanium alloys for spinal fixation devices  [Not invited]
    第127回東北大学金属材料研究所講演会  2014
  • Sliding wear behavior of Ti64/TNTZ combination for biomedical applications  [Not invited]
    第127回東北大学金属材料研究所講演会  2014
  • キャビテーションピーニングによるTi-6Al-4V ELI合金製脊椎固定器具の耐久性向上  [Not invited]
    ショットピーニング技術協会平成26年度学術講演会  2014
  • 酸素添加Ti-29Nb-13Ta-4.6Zr合金の力学的特性  [Not invited]
    軽金属学会第126回春期大会  2014
  • 浮揚溶解法および金属粉末射出成型法を用いて作製した低コストβ型Ti-Mn合金の力学的特性と微細組織  [Not invited]
    軽金属学会第126回春期大会  2014
  • Cr添加によるβ型Ti-Nb-Ta-Zr合金の弾性率自己調整機能化  [Not invited]
    軽金属学会第126回春期大会  2014
  • Ti-Mg合金におけるMg濃度と擬似体液へのMgイオンの溶出量との関係  [Not invited]
    日本歯科理工学会平成26年度春期第63回学術講演会  2014
  • 高圧ねじり加工を用いた微細組織制御による生体用Co-Cr-Mo合金の力学的特性の向上  [Not invited]
    日本歯科理工学会平成26年度春期第63回学術講演会  2014
  • Characterization of sliding friction-induced subsurface deformation of Ti-29Nb-13Ta-4.6Zr alloys for biomedical applications  [Not invited]
    日本金属学会2014年春期（第154回）大会および日本鉄鋼協会第167回春季講演大会（共同セッション）  2014
  • 金属粉末射出成形を用いて作製したβ型Ti-Mn合金の力学的特性に冷間圧延が及ぼす影響  [Not invited]
    日本金属学会2014年春期（第154回）大会および日本鉄鋼協会第167回春季講演大会（共同セッション）  2014
  • レーザー積層造形法により作製したCo-33Cr-5Mo-0.4N合金の疲労特性におよぼす造形方向の影響  [Not invited]
    日本金属学会2014年春期（第154回）大会  2014
  • Comparison of mechanical properties of low-cost β-type Ti-xMn alloys for biomedical applications fabricated by CCLM and MIM methods  [Not invited]
    日本金属学会2014年春期（第154回）大会  2014
  • Fatigue strength of β-type Ti-29Nb-13Ta-4.6Zr through high-pressure torsion after aging treatment  [Not invited]
    日本金属学会2014年春期（第154回）大会  2014
  • Changeable Young's modulus with twinning-induced plasticity in β-type titanium alloys for spinal fixture  [Not invited]
    日本金属学会2014年春期（第154回）大会  2014
  • 生体用β型チタン合金上に作製したハイドロキシアパタイト膜の擬生体環境を考慮した密着性評価  [Not invited]
    日本金属学会2014年春期（第154回）大会  2014
  • Ti-29Nb-13Ta-4.6Zr合金の弾性率自己調整機能化  [Not invited]
    日本金属学会2014年春期（第154回）大会  2014
  • 金属材料の力学的生体機能化  [Not invited]
    日本金属学会2014年春期（第154回）大会  2014
  • Microstructural Analysis of Biomedical Co-Cr-Mo Alloy subjected to High-Pressure Torsion Processing  [Not invited]
    2013 Annual Meeting of Excellent Graduate Schools for "Materials Integration Center" and "Materials Science Center" in conjunction with International Workshop on Advanced Materials Synthesis Process and Nanostructure  2014
  • Effect of subsurface deformation on sliding wear behavior of Ti-29Nb-13Ta-4.6Zr alloys for biomedical applications  [Not invited]
    2013 Annual Meeting of Excellent Graduate Schools for "Materials Integration Center" and "Materials Science Center" in conjunction with International Workshop on Advanced Materials Synthesis Process and Nanostructure  2014
  • 生体用ヤング率可変型チタン合金  [Not invited]
    特異構造金属・無機融合高機能材料開発共同研究プロジェクト第4回6大学6研究所連携プロジェクト公開討論会  2014
  • Fatigue behaviors of nanostructured β-type titanium alloys through high-pressure torsion  [Not invited]
    11th International Fatigue Congress (Fatigue2014)  2014
  • 硬組織適合性改善に向けた生体用β型チタン合金のハイドロキシアパタイト修飾  [Not invited]
    「生体材料のための金属表面処理技術」をテーマとしたミニ研究会  2014
  • Mechanical properties of biomedical β-type titanium alloy with yttrium oxide particles formed by yttrium addition  [Not invited]
    TMS2014 143rd Annual Meeting & Exhibition  2014
  • Difference of wear behavior between Ti-29Nb-13Ta-4.6Zr alloy and Ti-6Al-4V ELI alloy for biomedical applications  [Not invited]
    TMS2014 143rd Annual Meeting & Exhibition  2014
  • Fatigue characteristics and microstructures of laser welded and non-laser welded low cost Ti-4.5Al-2.5Cr-1.2Fe-0.1C for next generation aircrafts  [Not invited]
    TMS2014 143rd Annual Meeting & Exhibition  2014
  • Endurance of low-modulus beta-type titanium alloys for spinal fixation rods  [Not invited]
    TMS2014 143rd Annual Meeting & Exhibition  2014
  • Wear properties of interfaces composed of combinations of two-type titanium alloys for biomedical applications  [Not invited]
    The 5th International Symposium for Interface Oral Health Science  2014
  • Nanostructure and mechanical biocompatibility of β-type titanium alloys subjected to high-pressure torsion after aging treatmen  [Not invited]
    日本金属学会第12回東北支部研究発表大会  2014
  • Improvement of mechanical properties of Co-Cr-Mo alloy using a high pressure torsion  [Not invited]
    日本金属学会第12回東北支部研究発表大会  2014
  • Relationship between microstructures and mechanical properties of metal injection molded Ti-Mn alloys  [Not invited]
    日本金属学会第12回東北支部研究発表大会  2014
  • Influence of oxygen on changeable Young's modulus in oxygen added β-type Ti-10Cr alloy for spinal fixture  [Not invited]
    日本金属学会第12回東北支部研究発表大会  2014
  • Roles of subsurface deformation and strain localization in wear behavior of Ti-29Nb-13Ta-4.6Zr alloy for biomedical applications  [Not invited]
    日本金属学会第12回東北支部研究発表大会  2014
  • In-vitroおよびIn-vivo試験による低コストβ型Ti-Mn合金の生体適合性評価  [Not invited]
    日本金属学会第12回東北支部研究発表大会  2014
  • 生体用β型チタン合金上に作製したナノ微細構造膜と医療用高分子との密着性評価  [Not invited]
    日本金属学会第12回東北支部研究発表大会  2014
  • ナノチューブ構造を有するTNTZ表面への電解析出法によるハイドロキシアパタイトの均一コーティング  [Not invited]
    特異構造金属・無機融合高機能材料開発共同研究プロジェクト平成25年度生体・医療材料開発分野分科会  2014
  • 表面微細構造をもつTi-29Nb-13Ta-4.6Zr合金のセグメント化ポリウレタンによる修飾  [Not invited]
    特異構造金属・無機融合高機能材料開発共同研究プロジェクト平成25年度生体・医療材料開発分野分科会  2014
  • Ti-Nb-Ta-Zr合金製ロッドを用いた脊椎固定器具の圧縮疲労特性とその改善  [Not invited]
    特異構造金属・無機融合高機能材料開発共同研究プロジェクト平成25年度生体・医療材料開発分野分科会  2014
  • Investigation of biocompatibility of high strength low-cost β-type Ti-Mn alloys for biomedical applications  [Not invited]
    International Symposium on EcoTopia Science'13 (ISETS'13)  2013
  • Enhancement of mechanical biocompatibility of titanium alloys for load bearing implant devices with relation to elastic modulus  [Not invited]
    International Symposium on EcoTopia Science'13 (ISETS'13)  2013
  • Electrolytic deposition of hydroxyapatite on nanotubular Ti-29Nb-13Ta-4.6Zr oxide layer  [Not invited]
    Advanced Materials Development and Integration of Novel Structured Metallic and Inorganic Materials (AMDI4)  2013
  • Microstructure and mechanical properties of friction stir welded high-workability titanium alloys  [Not invited]
    Advanced Materials Development and Integration of Novel Structured Metallic and Inorganic Materials (AMDI4)  2013
  • In-situ corrosion monitoring of various metallic biomaterials in simulated body fluid  [Not invited]
    Advanced Materials Development and Integration of Novel Structured Metallic and Inorganic Materials (AMDI4)  2013
  • Compressive fatigue property of spinal fixation device with implant rods made of a beta titanium alloy for biomedical applications  [Not invited]
    Advanced Materials Development and Integration of Novel Structured Metallic and Inorganic Materials (AMDI4)  2013
  • Improvement of adhesive strength between Ti-29Nb-13Ta-4.6Zr alloy with Anodic oxide nanostructures and segmented polyurethane coating  [Not invited]
    Advanced Materials Development and Integration of Novel Structured Metallic and Inorganic Materials (AMDI4)  2013
  • Comparison of fatigue properties between laser-welded and friction-stir-welded Ti-4.5Al-2.5Cr-1.2Fe-0.1C alloy joints for aerospace applications  [Not invited]
    Advanced Materials Development and Integration of Novel Structured Metallic and Inorganic Materials (AMDI4)  2013
  • 陽極酸化による微細構造をもつβ型チタン合金上に作製した医療用高分子膜の密着強度  [Not invited]
    第23回日本MRS年次大会  2013
  • Wear properties of Ti-6Al-4V ELI/TNTZ combination for spinal implants  [Not invited]
    THERMEC'2013  2013
  • Mechanical and biological biocompatibility of newly developed beta-type Ti-Mn alloys for biomedical applications  [Not invited]
    THERMEC'2013  2013
  • Biomedical polymer surface modification of beta-type titanium alloy for implants through anodic oxide nanostructures  [Not invited]
    THERMEC'2013  2013
  • Relationship between heterogeneous microstructure and fatigue strength of Ti-Nb-Ta-Zr alloy subjected to aging treatments for biomedical materials  [Not invited]
    THERMEC'2013  2013
  • Optimization of Mo content in beta-type Ti-Mo alloys for obtaining larger changeable Young's modulus during deformation for use in spinal fixation applications  [Not invited]
    THERMEC'2013  2013
  • Formation of bio-functional surface layer and its bonding strength in low modulus beta-type titanium alloy for biomedical applications  [Not invited]
    THERMEC'2013  2013
  • 高生物学的生体適合性を有する生体用チタン合金の開発  [Not invited]
    第86回表面技術協会関東支支部若手講演会  2013
  • Investigation of relationship between microstructures and mechanical properties of Ti-Mn alloys fabricated by metal injection molding for biomedical applications  [Not invited]
    第126回東北大学金属材料研究所講演会  2013
  • 擬似生体環境および生体内での金属溶出に着目した新規生体用β型Ti-Mn合金の生体適合性評価  [Not invited]
    第126回東北大学金属材料研究所講演会  2013
  • 疑似体液浸漬によるTi-xMg合金薄膜の硬組織適合性評価  [Not invited]
    第126回東北大学金属材料研究所講演会  2013
  • 生体用β型チタン合金の表面形状制御とハイドロキシアパタイト膜の密着性評価  [Not invited]
    第126回東北大学金属材料研究所講演会  2013
  • Affecting factors on deformation-induced ω-phase transformation in oxygen added β-type Ti-10Cr alloys for spinal fixation applications  [Not invited]
    第126回東北大学金属材料研究所講演会  2013
  • Frictional wear characteristics of Ti64/TNTZ combination for spinal fixation devices  [Not invited]
    第126回東北大学金属材料研究所講演会  2013
  • Microstructure evaluation of biomedical β-type titanium alloys having dual phase through high-pressure torsion after aging treatment  [Not invited]
    第126回東北大学金属材料研究所講演会  2013
  • レーザー積層造形法により作製した高クロム高窒素含有Co-Cr-Mo合金の疲労特性  [Not invited]
    粉体粉末冶金協会平成25年度秋季大会（第112回講演大会）  2013
  • 表面形状制御による生体用β型チタン合金へのハイドロキシアパタイト膜の密着性改善  [Not invited]
    第35回日本バイオマテリアル学会大会  2013
  • 生体用β型チタン−マンガン合金の細胞試験および動物試験に基づいた生体適合性評価  [Not invited]
    第35回日本バイオマテリアル学会大会  2013
  • Ti-Mg合金における疑似体液への各種金属イオンの溶出量  [Not invited]
    第35回日本バイオマテリアル学会大会  2013
  • Effect of oxygen on changeable Young's modulus in β-type Ti-10Cr-O alloys for spinal fixture  [Not invited]
    第35回日本バイオマテリアル学会大会  2013
  • 弾性率自己調整金属製脊椎固定ロッドの曲げ特性  [Not invited]
    第35回日本バイオマテリアル学会大会  2013
  • Wear behavior of Ti64/TNTZ combination under dry sliding conditions  [Not invited]
    軽金属学会第125回秋期大会  2013
  • 弾性率自己調整Ti-Mo合金のミクロ組織と力学的特性  [Not invited]
    軽金属学会第125回秋期大会  2013
  • Microstructures and mechanical properties of Ti-Mn alloys for biomedical applications produced by metal injection molding and cold crucible levitation melting  [Not invited]
    日本機械学会 機械材料・材料加工部門 第21回機械材料・材料加工技術講演会 (M&P2013)  2013
  • ナノ微細構造を利用したTi-29Nb-13Ta-4.6Zr合金と医療用高分子膜との密着性改善  [Not invited]
    日本機械学会 機械材料・材料加工部門 第21回機械材料・材料加工技術講演会 (M&P2013)  2013
  • Effects of high-pressure torsion on corrosion behaviors of β-type titanium alloy in simulated body fluid  [Not invited]
    日本機械学会 機械材料・材料加工部門 第21回機械材料・材料加工技術講演会 (M&P2013)  2013
  • Microstructure and fatigue property of friction stir welded Ti-4.5Al-2.5Cr-1.2Fe-0.1C alloy for aerospace applications  [Not invited]
    1st International Joint Symposium on Joining and Welding -Friction Based Welding and Processing- (IJS-JW2013)  2013
  • Mechanical properties, microstructures and biocompatibility of low-cost beta-type Ti-Mn alloys for biomedical applications  [Not invited]
    Materials Science & Technology 2013 Conference & Exhibition (MS&T'13)  2013
  • Optimization of Cr and O contents in beta-type Ti-Cr-O alloys for obtaining both larger changeable Young's modulus during deformation and higher strength for use in spinal fixation applications  [Not invited]
    Materials Science & Technology 2013 Conference & Exhibition (MS&T'13)  2013
  • 高圧ねじり加工による生体用Co-Cr-Mo合金の微細組織制御  [Not invited]
    平成25年度秋期第62回日本歯科理工学会学術講演会  2013
  • 高温溶体化処理を施した銀パラジウム金銅合金における銅の濃度と微細組織および力学的特性との関係  [Not invited]
    平成25年度秋期第62回日本歯科理工学会学術講演会  2013
  • Investigation of mechanical biocompatibility of low-cost β-type Ti-Mn alloys for biomedical applications fabricated by metal injection molding  [Not invited]
    XII Brazilian MRS Meeting  2013
  • Improvement of mechanical strength of β-type Ti alloys through microstructural control using a high pressure torsion  [Not invited]
    XII Brazilian MRS Meeting  2013
  • Development of Ti-Zr based alloys with changeable Young's modulus for spinal fixation applications  [Not invited]
    XII Brazilian MRS Meeting  2013
  • Low modulus titanium alloys for fabricating rods for spinal fixation device  [Not invited]
    XII Brazilian MRS Meeting  2013
  • Influence of oxygen on deformation-induced changeable Young's modulus in β-type Ti-10Cr alloy  [Not invited]
    日本金属学会2013年秋期（第153回）大会および日本鉄鋼協会第166回秋季講演大会（共同セッション）  2013
  • Corrosion behavior of Ti-Cr alloys for biomedical applications  [Not invited]
    日本金属学会2013年秋期（第153回）大会  2013
  • ゾルゲル法により作製したハイドロキシアパタイト膜の密着性における生体用β型チタン合金の表面形状の影響  [Not invited]
    日本金属学会2013年秋期（第153回）大会  2013
  • Relationship between mechanical properties and microstructure of low-cost β-type Ti-Mn alloys for biomedical applications  [Not invited]
    日本金属学会2013年秋期（第153回）大会  2013
  • Characterization of subsurface deformation during dry sliding wear of new titanium TNTZ for biomedical applications  [Not invited]
    日本金属学会2013年秋期（第153回）大会  2013
  • 生体用低コストβ型Ti-Mn合金の動物試験による骨形成能評価および擬似体液中でのMnイオンの溶出量評価  [Not invited]
    日本金属学会2013年秋期（第153回）大会  2013
  • 擬似体液浸漬試験によるチタン-マグネシウム合金のハイドロキシアパタイト形成能の評価  [Not invited]
    日本金属学会2013年秋期（第153回）大会  2013
  • 大気中および疑似生体内環境中における生体用β型チタン合金製脊椎固定器具の圧縮疲労特性  [Not invited]
    日本金属学会2013年秋期（第153回）大会  2013
  • 脊椎固定用Ti-12Cr合金ロッドの曲げ特性  [Not invited]
    日本金属学会2013年秋期（第153回）大会  2013
  • Nano-structural control of β-type titanium alloys through severe plastic deformation  [Not invited]
    Advanced Materials World Congress (AMWC 2013)  2013
  • Severe subsurface deformation of TNTZ alloys under dry sliding wear condition  [Not invited]
    8th International Workshop on Biomaterials in Biosis-Abiosis Intelligent Interface Science (Innovative Research for Biosis-Abiosis Intelligent Interface Summer Seminar 2013)  2013
  • 次世代医療用チタン合金の開発と脊椎固定器具への応用  [Not invited]
    第1回東北大学メディカルサイエンス・シンポジウム  2013
  • Deformation induced changeable Young's modulus in ternary Ti-Cr-O alloys for spinal fixation applications  [Not invited]
    The 8th Pacific Rim International Conference on Advanced Materials and Processing (PRICM 8)  2013
  • Mechanical properties of low-cost beta-type Ti-Mn alloys fabricated by metal injection molding  [Not invited]
    The 8th Pacific Rim International Conference on Advanced Materials and Processing (PRICM 8)  2013
  • Microstructural control and mechanical properties of low cost titanium alloy for next generation aircraft  [Not invited]
    The 8th Pacific Rim International Conference on Advanced Materials and Processing (PRICM 8)  2013
  • Mechanical properties of Ti-12Cr alloy with self-tunable Young's modulus for use in spinal fixation devices  [Not invited]
    The 8th Pacific Rim International Conference on Advanced Materials and Processing (PRICM 8)  2013
  • Effect of aging treatment on corrosion susceptibilities of biomedical nanostructured β-type titanium alloys through severe plastic deformation  [Not invited]
    9th National Conference on Nanoscience and Nanotechnology (NanoTR-9)  2013
  • Development of mechanically biocompatible titanium alloys for fabricating biomedical implants  [Not invited]
    The 2nd International GIGAKU Conference in Nagaoka (IGCN2013)  2013
  • 各種表面処理を施したβ型チタン合金へのハイドロキシアパタイト膜の密着性評価  [Not invited]
    粉体粉末冶金協会平成25年度春季大会（第111回講演大会）  2013
  • 応力誘起ω相変態を利用した脊椎固定器具用チタン合金の機能化  [Not invited]
    粉体粉末冶金協会平成25年度春季大会（第111回講演大会）  2013
  • DCマグネトロンスパッタリング法により作製したTi-Mg膜における生理食塩水へのTiおよびMgの溶出量  [Not invited]
    第125回東北大学金属材料研究所講演会  2013
  • 高圧ねじり加工を用いた析出相の微細化による生体用β型チタン合金の力学的生体適合性の向上  [Not invited]
    第125回東北大学金属材料研究所講演会  2013
  • ゾルゲル法により生体用β型チタン合金上に作製したハイドロキシアパタイト膜の密着強度  [Not invited]
    第125回東北大学金属材料研究所講演会  2013
  • Microstructural evaluation of biomedical β-type titanium alloys through high-pressure torsion by X-ray line profile analysis  [Not invited]
    第125回東北大学金属材料研究所講演会  2013
  • Microstructures and mechanical properties of low-cost β-type Ti-Mn alloys fabricated by metal injection molding for biomedical applications  [Not invited]
    第125回東北大学金属材料研究所講演会  2013
  • Deformation induced changeable Young's modulus with high strength in β-type Ti-Cr-O alloys for spinal fixation applications  [Not invited]
    第125回東北大学金属材料研究所講演会  2013
  • Dry sliding wear of Ti-29Nb-13Ta-4.6Zr alloys with different amounts of interstitial element oxygen  [Not invited]
    第125回東北大学金属材料研究所講演会  2013
  • 変形誘起相変態を利用した生体用チタン合金の高機能化  [Not invited]
    第125回東北大学金属材料研究所講演会  2013
  • 生体用β型チタン合金の表面形状とゾルゲル法により作製したハイドロキシアパタイト膜の密着強度との関係  [Not invited]
    軽金属学会第124回春期大会  2013
  • 次世代航空機用α+β型チタン合金の疲労特性に及ぼす摩擦攪拌接合の影響  [Not invited]
    軽金属学会第124回春期大会  2013
  • Development of changeable Young's modulus with good mechanical properties in β-type Ti-Cr-O alloys  [Not invited]
    2nd International Congress on Advanced Materials (AM2013)  2013
  • Advances in development of titanium alloys for spinal fixation applications  [Not invited]
    2nd International Congress on Advanced Materials (AM2013)  2013
  • Changeable Young's modulus induced by deformation in biomedical Ti-Cr-O alloys for spinal fixation applications  [Not invited]
    日本金属学会2013年春期（第152回）大会および日本鉄鋼協会第165回春季講演大会（共同セッション）  2013
  • Ti-6Al-4V合金の疲労特性に及ぼす加工熱処理の影響  [Not invited]
    日本金属学会2013年春期（第152回）大会および日本鉄鋼協会第165回春季講演大会（共同セッション）  2013
  • 金属射出成形法を用いて作製した低コストβ型Ti-Mn合金の力学的生体適合性評価  [Not invited]
    日本金属学会2013年春期（第152回）大会  2013
  • 非平衡プロセスによるチタン-マグネシウム合金の作製と生理食塩水への溶出量評価  [Not invited]
    日本金属学会2013年春期（第152回）大会  2013
  • Microstructure evaluation of biomedical β-type titanium alloys through high-pressure torsion by X-ray diffraction line profile analysis  [Not invited]
    日本金属学会2013年春期（第152回）大会  2013
  • Frictional wear characteristics of Ti-29Nb-13Ta-4.6Zr alloys with different amount of interstitial element oxygen for spinal implants  [Not invited]
    日本金属学会2013年春期（第152回）大会  2013
  • 生体用β型チタン合金の脊椎固定用器具への応用  [Not invited]
    日本金属学会2013年春期（第152回）大会  2013
  • 摩擦攪拌接合を施した次世代航空機用α+β型チタン合金の疲労特性  [Not invited]
    日本金属学会2013年春期（第152回）大会  2013
  • Effect of Cr and O contents on Young's moduli of Ti-Cr-O alloys before and after deformation  [Not invited]
    Excellent Graduate Schools 2012 Annual Meeting & Japan-Russia Workshop on Advanced Materials Synthesis Process and Nanostructure  2013
  • Frictional wear behavior of Ti-29Nb-13Ta-4.6Zr alloys with different amount of interstitial element oxygen  [Not invited]
    Excellent Graduate Schools 2012 Annual Meeting & Japan-Russia Workshop on Advanced Materials Synthesis Process and Nanostructure  2013
  • Development of mechanical biocompatibility of low-modulus beta-type titanium alloy by introducing ultrafine-grain structure through high-pressure torsion  [Not invited]
    TMS2013 142nd Annual Meeting & Exhibition  2013
  • Research and development of low-cost titanium alloys for biomedical applications  [Not invited]
    TMS2013 142nd Annual Meeting & Exhibition  2013
  • Effect of microstructural control by severe plastic deformation on mechanical behavior of β-type titanium alloys  [Not invited]
    第11回日本金属学会東北支部研究発表大会  2012
  • 生体用β型チタン合金における希土類金属添加による酸化物析出とその力学的特性への影響  [Not invited]
    第11回日本金属学会東北支部研究発表大会  2012
  • Recently developed titanium alloys for spinal fixation applications  [Not invited]
    21th International Symposium on Processing and Fabrication of Advanced Materials (PFAM XXI)  2012
  • Improvement of mechanical strength of titanium alloys by microstructural refinement down to nano-size through high pressure torsion  [Not invited]
    21th International Symposium on Processing and Fabrication of Advanced Materials (PFAM XXI)  2012
  • Microstructural evaluation of β-type Ti-29Nb-13Ta-4.6Zr through high-pressure torsion after cold rolling and aging treatment  [Not invited]
    日本機械学会 機械材料・材料加工部門 第20回機械材料・材料加工技術講演会 (M&P2012)  2012
  • Self-adjustment of Young's modulus due to deformation in biomedical Ti-Cr alloys with high oxygen content  [Not invited]
    日本機械学会 機械材料・材料加工部門 第20回機械材料・材料加工技術講演会 (M&P2012)  2012
  • 高圧ねじり加工を用いた微細組織制御による生体用Ti-29Nb-13Ta-4.6Zr合金の力学的生体適合性向上  [Not invited]
    日本機械学会 機械材料・材料加工部門 第20回機械材料・材料加工技術講演会 (M&P2012)  2012
  • Wear behavior of Ti-29Nb-13Ta-4.6Zr alloys with different amount of interstitial oxygen for spinal implants  [Not invited]
    日本機械学会 機械材料・材料加工部門 第20回機械材料・材料加工技術講演会 (M&P2012)  2012
  • フッ化物溶液に浸漬したTi-Nb-Ta-Zr合金の表面分析  [Not invited]
    日本バイオマテリアル学会シンポジウム2012  2012
  • 表面改質処理を施したβ型チタン合金のミクロ組織と力学的特性の関係  [Not invited]
    日本バイオマテリアル学会シンポジウム2012  2012
  • 成犬下顎骨モデルにおける生体用β型Ti-29Nb-13Ta-4.6Zr合金の検討〜歯科用インプラント材料への臨床応用を目指して〜  [Not invited]
    日本バイオマテリアル学会シンポジウム2012  2012
  • Deformation induced changeable Young's modulus in biomedical Ti-Cr alloys with high oxygen content  [Not invited]
    日本バイオマテリアル学会シンポジウム2012  2012
  • Changeable Young's modulus in modified Ti-29Nb-13Ta-4.6Zr by Cr addition  [Not invited]
    日本バイオマテリアル学会シンポジウム2012  2012
  • 熱処理による歯科用Ag-20Pd-12Au-14.5Cu合金のミクロ組織の変化と硬化の関係  [Not invited]
    日本バイオマテリアル学会シンポジウム2012  2012
  • 生体用Ti-Nb-Ta-Zr合金のミクロ偏析が力学的特性に及ぼす影響  [Not invited]
    日本バイオマテリアル学会シンポジウム2012  2012
  • 生体用高分子被覆β型チタン合金の開発とその接着性評価  [Not invited]
    日本バイオマテリアル学会シンポジウム2012  2012
  • 弾性率自己調整Ti-12Cr合金の力学的特性  [Not invited]
    日本バイオマテリアル学会シンポジウム2012  2012
  • Mechanical performance of α+β type titanium alloy subjected to friction stir welding for next-generation air crafts  [Not invited]
    Materials Science Week 2012 (MSW2012)  2012
  • Wear resistances of Ti-29Nb-13Ta-4.6Zr alloys with different contents of interstitial element, oxygen for spinal implants  [Not invited]
    Materials Science Week 2012 (MSW2012)  2012
  • Changeable Young's modulus induced by deformation in biomedical Ti-Cr alloys with high oxygen content  [Not invited]
    Materials Science Week 2012 (MSW2012)  2012
  • Improvement of adhesive strength between medical polymer and anodic oxidized beta-type titanium alloy  [Not invited]
    Materials Science Week 2012 (MSW2012)  2012
  • 表面形状制御生体用β型チタン合金への医療用ポリマーの密着性評価  [Not invited]
    軽金属学会第123回秋期大会  2012
  • 摩擦攪拌接合を施した次世代航空機用α+β型チタン合金の微細組織と機械的特性の関係  [Not invited]
    軽金属学会第123回秋期大会  2012
  • Wear properties of Ti-29Nb-13Ta-4.6Zr alloys with interstitial element oxygen for biomedical applications  [Not invited]
    軽金属学会第123回秋期大会  2012
  • 脊椎固定用Ti-12Cr合金のミクロ組織と力学的特性  [Not invited]
    軽金属学会第123回秋期大会  2012
  • Optimization of chemical composition of biomedical Ti-Cr alloys with self-tunable Young's modulus  [Not invited]
    The 5th International Symposium on Designing, Processing and Properties of Advanced Engineering Materials (ISAEM-2012) & the 3rd International Symposium on Advanced Materials Development and Integration of Novel Structural Metallic and Inorganic Materi・・・  2012
  • Self-organized Ti?Nb?Ta?Zr?O mixed oxide nanotubes array and its applications  [Not invited]
    The 5th International Symposium on Designing, Processing and Properties of Advanced Engineering Materials (ISAEM-2012) & the 3rd International Symposium on Advanced Materials Development and Integration of Novel Structural Metallic and Inorganic Materi・・・  2012 
    The 5th International Symposium on Designing, Processing and Properties of Advanced Engineering Materials (ISAEM-2012) & the 3rd International Symposium on Advanced Materials Development and Integration of Novel Structural Metallic and Inorganic Materials (AMDI-3)
  • Investigation of relationship between alloying elements and HAp formability for beta-type Ti-29Nb-13Ta-4.6Zr alloy through alkali treatment process  [Not invited]
    The 5th International Symposium on Designing, Processing and Properties of Advanced Engineering Materials (ISAEM-2012) & the 3rd International Symposium on Advanced Materials Development and Integration of Novel Structural Metallic and Inorganic Materi・・・  2012
  • Modified Ti-29Nb-13Ta-4.6Zr for wide applications in biomedical fields  [Not invited]
    The 5th International Symposium on Designing, Processing and Properties of Advanced Engineering Materials (ISAEM-2012) & the 3rd International Symposium on Advanced Materials Development and Integration of Novel Structural Metallic and Inorganic Materi・・・  2012
  • Effect of oxide particles formed through addition of rare-earth metal on mechanical properties of biomedical β-type titanium alloy  [Not invited]
    The 5th International Symposium on Designing, Processing and Properties of Advanced Engineering Materials (ISAEM-2012) & the 3rd International Symposium on Advanced Materials Development and Integration of Novel Structural Metallic and Inorganic Materi・・・  2012
  • Aging behavior of biomedical beta Ti-Nb-Ta-Zr alloy with homogeneous and inhomogeneous compositional distribution  [Not invited]
    The 5th International Symposium on Designing, Processing and Properties of Advanced Engineering Materials (ISAEM-2012) & the 3rd International Symposium on Advanced Materials Development and Integration of Novel Structural Metallic and Inorganic Materi・・・  2012
  • Corrosion resistance of Ti-29Nb-13Ta-4.6Zr alloy in a fluoride-containing solution  [Not invited]
    24th Symposium and Annual Meeting of International Society for Ceramics in Medicine (ISCM) (Bioceramics 24)  2012
  • フッ化物溶液中でのTi-Nb-Ta-Zr合金の電気化学腐食挙動  [Not invited]
    平成24年度秋期第60回日本歯科理工学会学術講演会  2012
  • アルカリ処理による生体用β型チタン合金のハイドロキシアパタイト被覆における合金元素の影響  [Not invited]
    平成24年度秋期第60回日本歯科理工学会学術講演会  2012
  • 時効処理を施したAg-20Pd-12Au-14.5Cu合金におけるミクロ組織と硬化  [Not invited]
    平成24年度秋期第60回日本歯科理工学会学術講演会  2012
  • Enhancing biological biocompatibility of low modulus β-type titanium alloy through bioactive ceramic and bio-polymer surface modification  [Not invited]
    15th International Conference on Advances in Materials and Processing Technologies (AMPT2012)  2012
  • Fabrication of β-type titanium alloy with hard-tissue compatibility through HAp deposition by MOCVD method  [Not invited]
    International Union of Materials Research Societies & International Conference on Electronic Materials 2012 (IUMRS-ICEM 2012)  2012
  • Young's modulus change via deformation-induced phase transformation in biomedical Ti-Cr alloys with a high oxygen content  [Not invited]
    日本金属学会2012年秋期（第151回）大会  2012
  • 表面処理を施した生体用β型チタン合金の表面形状とHAp膜密着性への影響  [Not invited]
    日本金属学会2012年秋期（第151回）大会  2012
  • 高圧ねじり加工を用いた生体用β型チタン合金の力学的生体適合性向上  [Not invited]
    日本金属学会2012年秋期（第151回）大会  2012
  • 陽極酸化による生体用β型チタン合金の表面形状制御と密着力評価  [Not invited]
    日本金属学会2012年秋期（第151回）大会  2012
  • 歯科用Ag-20Pd-12Au-xCu合金における高温溶体化処理による析出相β'とその析出過程  [Not invited]
    日本金属学会2012年秋期（第151回）大会  2012
  • Aging behavior of TiNb24Zr2 alloy with superelasticity  [Not invited]
    日本金属学会2012年秋期（第151回）大会  2012
  • 生体用β型チタン合金に存在するミクロ偏析と力学的特性との関係  [Not invited]
    日本金属学会2012年秋期（第151回）大会  2012
  • 粉末冶金法により作製した歯科用コバルトクロム合金の窒素含有量と機械的性質  [Not invited]
    日本金属学会2012年秋期（第151回）大会（公募シンポジウム）  2012
  • 次世代航空機用α+β型チタン合金の微細組織および機械的特性に及ぼす摩擦攪拌接合の影響  [Not invited]
    日本鉄鋼協会第164回秋季講演大会（共同セッション）  2012
  • Relationship between surface morphology of biomedical β-type titanium alloy and adhesiveness of hydroxyapatite films  [Not invited]
    International Workshop on Biomaterials in Biosis-Abiosis Intelligent Interface Science-Innovation Research for Biosis-Abiosis Intelligent Interface Summer Seminar 2012-  2012
  • Comparison of fatigue strength of a biomedical β titanium alloy added with pure rare earth and rare earth oxides  [Not invited]
    The 8th International Forum on Advanced Material Science and Technology (IFAMST-8)  2012
  • Development of novel titanium alloys with changeable Young's modulus for spinal fixation rods applications  [Not invited]
    9th World Biomaterials Congress (9th WBC)  2012
  • Enhancing biocompatibility of a β-type titanium alloy by HAp film coating by MOCVD and evaluation of its mechanical biocompatibility  [Not invited]
    9th World Biomaterials Congress (9th WBC)  2012
  • Ti-Cr alloys with changeable Young's modulus for spinal fixation devices  [Not invited]
    9th World Biomaterials Congress (9th WBC)  2012
  • 陽極酸化による生体用低弾性率β型チタン合金の表面形状制御  [Not invited]
    第123回東北大学金属材料研究所講演会  2012
  • 摩擦攪拌接合による結晶粒微細化処理を施した生体用β型チタン合金の力学的特性  [Not invited]
    第123回東北大学金属材料研究所講演会  2012
  • The effects of interstitial content on the tensile properties of Ti-29Nb-13Ta-4.6Zr  [Not invited]
    第123回東北大学金属材料研究所講演会  2012
  • 表面形状制御による医療用高分子/Ti-29Nb-13Ta-4.6Zr合金の密着性向上  [Not invited]
    軽金属学会第122回春期大会  2012
  • 表面粗さを制御した生体用β型チタン合金へのMOCVD-HAp膜の密着性評価  [Not invited]
    軽金属学会第122回春期大会  2012
  • 次世代航空機用α+β型チタン合金薄板の加工熱処理による力学的異方性の改善  [Not invited]
    軽金属学会第122回春期大会  2012
  • 高温溶体化処理を施したAg-20Pd-12Au-14.5Cu合金におけるβ'相生成メカニズム  [Not invited]
    平成24年度春期(第59回)日本歯科理工学会学術講演会  2012
  • 摩擦攪拌接合を施したチタン合金の微細組織および機械的特性  [Not invited]
    溶接学会平成24年度春季全国大会  2012
  • 生体用ヤング率自己調整型チタン合金の開発  [Not invited]
    日本鉄鋼協会第163回春季講演大会  2012
  • 摩擦攪拌接合を施した生体用β型チタン合金の微細組織と力学的性質  [Not invited]
    日本金属学会2012年春期（第150回）大会  2012
  • Mechanical functionalization of β-type Ti-29Nb-13Ta-4.6Zr through severe plastic deformation after aging treatment  [Not invited]
    日本金属学会2012年春期（第150回）大会  2012
  • Relationship between deformation-induced product and Young's modulus in metastable β-type Ti-Cr and Ti-Mo alloys for spinal fixation applications  [Not invited]
    日本金属学会2012年春期（第150回）大会  2012
  • 希土類金属添加生体用β型チタン合金における酸化物粒子析出と力学的特性  [Not invited]
    日本金属学会2012年春期（第150回）大会  2012
  • 長時間均質化処理を施した生体用β型チタン合金のミクロ組織と力学的特性  [Not invited]
    日本金属学会2012年春期（第150回）大会  2012
  • Influence of interstitial oxygen content on tensile properties of hot rolled Ti-29Nb-13Ta-4.6Zr  [Not invited]
    日本金属学会2012年春期（第150回）大会  2012
  • Precipitation process of β' phase and unique hardening behavior of as-solutionized Ag-20Pd-12Au-xCu alloys  [Not invited]
    平成23年度東北大学グローバルCOEプログラム「材料インテグレーション国際教育研究拠点」若手研究者研究報告会  2012
  • Tensile properties of Ti-29Nb-13Ta-4.6Zr with high oxygen content for biomedical applications  [Not invited]
    平成23年度東北大学グローバルCOEプログラム「材料インテグレーション国際教育研究拠点」若手研究者研究報告会  2012
  • Young's modulus change due to deformation in biomedical Ti-Cr alloys with a high oxygen content  [Not invited]
    平成23年度東北大学グローバルCOEプログラム「材料インテグレーション国際教育研究拠点」若手研究者研究報告会  2012
  • Effect of Mo content on deformation-induced phase transformation and mechanical twinning in Ti-Mo alloys for spinal fixation applications  [Not invited]
    平成23年度東北大学グローバルCOEプログラム「材料インテグレーション国際教育研究拠点」若手研究者研究報告会  2012
  • Improvement of mechanical biocompatibilities of β-type Ti-29Nb-13Ta-4.6Zr by controlling precipitated phases through high-pressure torsion after aging treatment  [Not invited]
    平成23年度東北大学グローバルCOEプログラム「材料インテグレーション国際教育研究拠点」若手研究者研究報告会  2012
  • Mechanical and adhesive properties of hydroxyapatite films pepared on Ti-29Nb-13Ta-4.6Zr alloy  [Not invited]
    International Symposium of GCOE: Materials Integration  2011
  • Increase of hardness and the precipitation of β' phase in as-solutionized Ag-Pd-Au-Cu alloy system  [Not invited]
    International Symposium of GCOE: Materials Integration  2011
  • Microstructure and mechanical properties of a biomedical β-type titanium alloy subjected to severe plastic deformation after aging treatment  [Not invited]
    International Symposium of GCOE: Materials Integration  2011
  • Difference of microstructure and fatigue properties between forged and rolled Ti-6Al-4V  [Not invited]
    International Symposium of GCOE: Materials Integration  2011
  • Young's modulus changeable β-type binary Ti-Cr alloys for spinal fixation applications  [Not invited]
    International Symposium of GCOE: Materials Integration  2011
  • Development of porous titanium filled with poly-L-lactic acid by modified in-situ polymerization technique  [Not invited]
    Fray International Symposium  2011
  • Mechanically bio-functional titanium alloys for substituting failed hard tissue  [Not invited]
    Fray International Symposium  2011
  • 酸素捕集型レアアース金属添加による生体用β型チタン合金の酸化物粒子分散強化  [Not invited]
    第122回東北大学金属材料研究所講演会  2011
  • 溶体化処理を施した歯科用銀パラジウム金銅合金中の析出物と硬化挙動の関係  [Not invited]
    第122回東北大学金属材料研究所講演会  2011
  • Effect of interstitial element oxygen on tensile properties of Ti-29Nb-13Ta-4.6Zr  [Not invited]
    第122回東北大学金属材料研究所講演会  2011
  • Mechanical functionalization of a biomedical β-type titanium alloy through severe plastic deformation combined with aging treatment  [Not invited]
    第122回東北大学金属材料研究所講演会  2011
  • Young's modulus change due to deformation in Ti-Mo alloys for spinal fixation devices  [Not invited]
    第122回東北大学金属材料研究所講演会  2011
  • 結晶粒微細化処理を施したTi-29Nb-13Ta-4.6Zr 合金の力学的特性  [Not invited]
    第122回東北大学金属材料研究所講演会  2011
  • MAOおよび化学処理によるTNTZ 合金のリン酸カルシウム形成促進  [Not invited]
    第33回日本バイオマテリアル学会大会  2011
  • MOCVD法によるTNTZ表面へのHAp膜の合成と生体適合性評価  [Not invited]
    第33回日本バイオマテリアル学会大会  2011
  • 生体用チタン合金の弾性率自己調整機能化  [Not invited]
    第33回日本バイオマテリアル学会大会  2011
  • 希土類金属の添加による生体用β型チタン合金の酸化物粒子分散強化  [Not invited]
    軽金属学会第121回秋期大会  2011
  • 生体用Ti-29Nb-13Ta-4.6Zr合金の結晶粒微細化と力学的特性  [Not invited]
    軽金属学会第121回秋期大会  2011
  • Effect of deformation-induced phase on mechanical properties of Ti-Mo alloys for spinal fixation devices  [Not invited]
    軽金属学会第121回秋期大会  2011
  • Effect of high-pressure torsion on microstructures and mechanical properties of biomedical β-type Ti-29Nb-13Ta-4.6Zr after aging treatment  [Not invited]
    軽金属学会第121回秋期大会  2011
  • MOCVD法によるTi-29Nb-13Ta-4.6Zr表面へのハイドロキシアパタイト膜の合成と生体適合性評価  [Not invited]
    軽金属学会第121回秋期大会  2011
  • ミクロ偏析を有する生体用Ti-29Nb-13Ta-4.6Zr合金の力学的特性  [Not invited]
    軽金属学会第121回秋期大会  2011
  • 歯科鋳造用 Au-Ag-Pd-Cu 合金の熱処理による耐食性の変化  [Not invited]
    日本金属学会2011年秋期（第149回）大会  2011
  • 生体用β型チタン合金へのMOCVD法によるHAp膜の合成と密着性評価  [Not invited]
    日本金属学会2011年秋期（第149回）大会  2011
  • Mechanical biocompatibility of metastable Ti-30Zr-(Cr, Mo) alloys with deformation-induced phase transformation  [Not invited]
    日本金属学会2011年秋期（第149回）大会  2011
  • 生体用β型チタン合金への希土類金属添加が力学的強度におよぼす影響  [Not invited]
    日本金属学会2011年秋期（第149回）大会  2011
  • ベンディング後の脊椎固定用インプラントロッドの経時形状回復特性  [Not invited]
    日本金属学会2011年秋期（第149回）大会  2011
  • 歯科用Ag-Pd-Au-xCu合金における高温溶体化処理によるL10型規則相(β')と硬化挙動  [Not invited]
    日本金属学会2011年秋期（第149回）大会  2011
  • Effect of Mo content on Young's modulus changeability of binary Ti-Mo alloys for spinal fixture  [Not invited]
    日本金属学会2011年秋期（第149回）大会  2011
  • 冷間スウェージング加工を施した生体用β型チタン合金の機械的性質およびヤング率に及ぼす結晶粒微細化の影響  [Not invited]
    日本金属学会2011年秋期（第149回）大会  2011
  • 次世代航空機用α+β型チタン合金薄板の力学的異方性に及ぼす加工熱処理の影響  [Not invited]
    日本金属学会2011年秋期（第149回）大会  2011
  • Mechanical properties of Ti-29Nb-13Ta-4.6Zr with high oxygen content for biomedical applications  [Not invited]
    日本金属学会2011年秋期（第149回）大会  2011
  • Microstructure of Ti-29Nb-13Ta-4.6Zr subjected to high-pressure torsion after aging treatment  [Not invited]
    日本金属学会2011年秋期（第149回）大会  2011
  • 生体用高分子/Ti-29Nb-13Ta-4.6Zr 合金界面における接着性の改善  [Not invited]
    日本金属学会2011年秋期（第149回）大会  2011
  • 生体用β型Ti-29Nb-13Ta-4.6Zr合金のミクロ組織および力学的特性に及ぼすミクロ偏析の影響  [Not invited]
    日本金属学会2011年秋期（第149回）大会  2011
  • Heterogeneous grain refinement of biomedical Ti-29Nb-13Ta-4.6Zr alloy through high-pressure torsion  [Not invited]
    The 3rd International Conference on UltraFine Grained and Nano-Structured Materials (UFGNSM 2011)  2011
  • Titanium alloys with improved mechanical biocompatibilities for spinal rods  [Not invited]
    The 3rd International Conference on UltraFine Grained and Nano-Structured Materials (UFGNSM 2011)  2011
  • 表面粗さ制御によるTNTZ合金上へのMOCVD-HAp膜の高密着化  [Not invited]
    粉体粉末冶金協会平成23年度秋季大会（第108回講演大会）  2011
  • ポーラスチタン/生分解性高分子コンポジット材料の作製と力学的特性評価  [Not invited]
    粉体粉末冶金協会平成23年度秋季大会（第108回講演大会）  2011
  • 生体用β型チタン合金/高分子接着性へのシランカップリング剤官能基の影響  [Not invited]
    平成23年度秋期（第58回）日本歯科理工学会学術講演会  2011
  • 歯科用Ag-Pd-Cu-Au合金におけるL10型規則相と特異硬化  [Not invited]
    平成23年度秋期（第58回）日本歯科理工学会学術講演会  2011
  • Young's modulus changeable biomedical titanium alloy for preventing stress shielding and spring-back  [Not invited]
    Materials Science and Technology 2011 Conference and Exhibition (MS&T'11)  2011
  • 応力誘起相変態を利用した生体用チタン合金の弾性率自己調整機能化  [Not invited]
    東北大学金属材料研究所ワークショップおよび日本バイオマテリアル学会東北地域講演会「次世代金属系バイオマテリアル開発の新たな展開」  2011
  • 次世代航空機用α+β型チタン合金薄板のミクロ組織および力学的特性に及ぼす熱間圧延温度の影響  [Not invited]
    日本鉄鋼協会第162回秋季講演大会  2011
  • セラミックス粒子添加による生体用β型チタン合金の力学的特性の向上  [Not invited]
    日本鉄鋼協会第162回秋季講演大会  2011
  • Development of new Ti-Mo alloys with changeable Young's modulus for spinal fixture devices  [Not invited]
    International Conference on Advanced Technology in Experimental Mechanics 2011 (ATEM'11)  2011
  • Relationship between Cu content and unique hardening behavior in as-solutionized Ag-Pd-Au-xCu alloys at high temperature  [Not invited]
    International Conference on Advanced Technology in Experimental Mechanics 2011 (ATEM'11)  2011
  • Effects of thermo-mechanical treatments on fatigue properties of Ti-6Al-4V  [Not invited]
    International Conference on Advanced Technology in Experimental Mechanics 2011 (ATEM'11)  2011
  • Development of thermomechanical treatment for improving fatigue strength and maintaining low Young's modulus in biomedical Ti-29Nb-13Ta-4.6Zr alloy by optimizing ω phase precipitation  [Not invited]
    International Conference on Advanced Technology in Experimental Mechanics 2011 (ATEM'11)  2011
  • Mechanical performances of biomedical beta-type titanium alloy through heat treatment and severe plastic deformation  [Not invited]
    Materials and Processes for Medical Devices (MPMD) 2011 Conference and Exposition  2011
  • Young's modulus change due to deformation-induced phase transformation in beta-type titanium alloys for biomedical applications  [Not invited]
    Materials and Processes for Medical Devices (MPMD) 2011 Conference and Exposition  2011
  • Unique hardening behavior of dental Ag-Pd-Au-Cu alloy by precipitation of L10-type ordered phase  [Not invited]
    The 6th International Workshop on Nano-, Bio- and Amorphous Materials  2011
  • Bending properties of β titanium alloys for biomedical applications  [Not invited]
    The 6th International Workshop on Nano-, Bio- and Amorphous Materials  2011
  • Unordinaly effect of oxygen on mechanical behavior of a beta-type titanium alloy for biomedical applications  [Not invited]
    THERMEC'2011  2011
  • Young's modulus changeable titanium alloys for orthopaedic applications  [Not invited]
    THERMEC'2011  2011
  • 次世代航空機用α+β型Ti-4.5Al-2.5Cr-1.2Fe-0.1C合金におけるミクロ組織および力学的特性に及ぼすレーザー溶接の影響  [Not invited]
    溶接学会東北支部第23回溶接・接合研究会  2011
  • Improvement of hard-tissue compatibility of Ti-29Nb-13Ta-4.6Zr alloy by micro-arc oxidation treatment  [Not invited]
    The 3rd International Symposium on Surface and Interface of Biomaterials (SIB2011)  2011
  • Effect of surface roughness on fabrication of hydroxyapatite film on β-type titanium alloy by MOCVD process  [Not invited]
    The 5th International Conference on the Science and Technology for Advanced Ceramics (STAC5) and The 2nd International Conference on Advanced Materials Development and Integration of Novel Structured Metallic and Inorganic Materials (AMDI2)  2011
  • Biocompatible β-type titanium alloy with hydroxyapatite surface prepared by MOCVD method  [Not invited]
    The 5th International Conference on the Science and Technology for Advanced Ceramics (STAC5) and The 2nd International Conference on Advanced Materials Development and Integration of Novel Structured Metallic and Inorganic Materials (AMDI2)  2011
  • Development of biomedical Ti-Cr alloys with changeable Young's modulus via deformation-induced transformation  [Not invited]
    The 12th World Conference on Titanium (Ti-2011)  2011
  • Development of new titanium alloys with changeable Young's modulus for spinal fixation application  [Not invited]
    The 12th World Conference on Titanium (Ti-2011)  2011
  • Improvement in fatigue strength with maintaining Young's modulus low by controlling ω-phase precipitation in β-type Ti-Nb-Ta-Zr alloy  [Not invited]
    The 12th World Conference on Titanium (Ti-2011)  2011
  • Dependence of silane coupling agent on shear bonding strength between titanium alloy and segmented polyurethane after immersion in water  [Not invited]
    International Dental Materials Congress 2011 (IDMC2011)  2011
  • Unique hardening behavior of dental Ag-Pd-Au-Cu alloys with different Cu contents through solution treatment  [Not invited]
    International Dental Materials Congress 2011 (IDMC2011)  2011
  • 歯科用Ag-Pd-Au-Cu合金のミクロ組織と耐食性  [Not invited]
    第121回東北大学金属材料研究所講演会  2011
  • ホウ素あるいはイットリウムの微量添加による生体用β型チタン合金の力学的生体適合性の改善  [Not invited]
    第121回東北大学金属材料研究所講演会  2011
  • MOCVD法によるHAp膜合成に及ぼす生体用β型チタン合金の表面粗さの影響  [Not invited]
    第121回東北大学金属材料研究所講演会  2011
  • スウェージング加工を施したTi-29Nb-13Ta-4.6Zr合金の力学的特性に及ぼす結晶粒微細化の影響  [Not invited]
    第121回東北大学金属材料研究所講演会  2011
  • 次世代航空機用α+β型チタン合金冷延材のミクロ組織および力学的特性に及ぼす熱間圧延の影響  [Not invited]
    第121回東北大学金属材料研究所講演会  2011
  • レーザー溶接した次世代航空機用α+β型チタン合金の力学的特性とミクロ組織  [Not invited]
    軽金属学会第120回春期大会  2011
  • レアアース酸化物分散強化生体用β型チタン合金の力学的生体適合性  [Not invited]
    軽金属学会第120回春期大会  2011
  • MOCVD法による生体用β型チタン合金表面へのHAp膜合成に及ぼす表面粗さの影響  [Not invited]
    軽金属学会第120回春期大会  2011
  • 生体用β型チタン合金の機械的特性に及ぼす結晶粒サイズの影響  [Not invited]
    軽金属学会第120回春期大会  2011
  • 脊椎固定用ヤング率可変型チタン合金の開発  [Not invited]
    軽金属学会第120回春期大会  2011
  • Effect of microstructure on fatigue properties of Ti-6Al-4V  [Not invited]
    日本鉄鋼協会第161回春季講演大会  2011
  • 次世代航空機用α+β型チタン合金の力学的特性およびミクロ組織に及ぼすレーザー溶接の影響  [Not invited]
    日本鉄鋼協会第161回春季講演大会  2011
  • ヤング率自己適応型生体用チタン合金の開発  [Not invited]
    日本鉄鋼協会第161回春季講演大会  2011
  • Effect of deformation-induced phase transformation on mechanical biocompatibility of Ti-30Zr-(Cr, Mo) alloys  [Not invited]
    加工プロセスによる材料新機能発現第176委員会 第18回研究会「今後の研究・開発の新展開に向けて」  2011
  • 冷間スウェージング加工および冷間溝ロール圧延加工後に時効処理を施した生体用β型チタン合金の力学的特性  [Not invited]
    加工プロセスによる材料新機能発現第176委員会 第18回研究会「今後の研究・開発の新展開に向けて」  2011
  • Effect of deformation-induced phase transformation on mechanical biocompatibility of metastable Ti-30Zr-(Cr, Mo) alloys  [Not invited]
    平成22年度東北大学グローバルCOEプログラム「材料インテグレーション国際教育研究拠点」若手研究者研究報告会  2011
  • Effect of deformation-induced transformation on mechanical properties of Ti-Mo alloys for biomedical applications  [Not invited]
    平成22年度東北大学グローバルCOEプログラム「材料インテグレーション国際教育研究拠点」若手研究者研究報告会  2011
  • Effect of HPT processing on microstructure of a biomedical beta-type aged Ti-29Nb-13Ta-4.6Zr alloy  [Not invited]
    平成22年度東北大学グローバルCOEプログラム「材料インテグレーション国際教育研究拠点」若手研究者研究報告会  2011
  • Acicular and ellipsoidal α phase in a biomedical β type titanium alloy subjected to thermo-mechanical treatment  [Not invited]
    平成22年度東北大学グローバルCOEプログラム「材料インテグレーション国際教育研究拠点」若手研究者研究報告会  2011
  • L10 type-ordered phase (β') precipitated in as-solutionized Ag-Pd-Au-Cu system alloys  [Not invited]
    平成22年度東北大学グローバルCOEプログラム「材料インテグレーション国際教育研究拠点」若手研究者研究報告会  2011
  • Microstructure and fatigue properties of forged and rolled Ti-6Al-4V  [Not invited]
    平成22年度東北大学グローバルCOEプログラム「材料インテグレーション国際教育研究拠点」若手研究者研究報告会  2011
  • 弾性率が変化する新しい生体用チタン合金の開発  [Not invited]
    平成22年度医工学研究科研究科発表会  2011
  • Improvement of mechanical strength of a β-type titanium alloy for biomedical applications with keeping Young's modulus low by adding a small amount of TiB2 or Y2O3  [Not invited]
    19th International Symposium on Processing and Fabrication of Advanced Materials (PFAM XIX)  2011
  • Relationship between mechanical properties and precipitated α phases in a biomedical β type titanium alloy subjected to thermo-mechanical treatment  [Not invited]
    Tohoku-Harvard GCOE Program Research Student Workshop  2011
  • β型チタン合金の機能性に及ぼす酸素の影響  [Not invited]
    日本金属学会 機能性チタン合金研究会第3回講演会「チタン合金のユビキタス化に向けての合金元素の役割」  2010
  • イントリンシック構造のプロセスデザイン  [Not invited]
    加工プロセスによる材料新機能発現第176委員会 第17回研究会「シンプルアロイデザインに向けたイントリンシックナノ材料科学」  2010
  • Change in microstructure of biomedical β-type Ti-29Nb-13Ta-4.6Zr through high-pressure torsion  [Not invited]
    7th Materials Science School for Young Scientists (KINKEN-WAKATE 2010)  2010
  • Microstructures and mechanical properties of Ti-Cr alloys for spinal fixture devices  [Not invited]
    7th Materials Science School for Young Scientists (KINKEN-WAKATE 2010)  2010
  • Mechanical properties of metastable Ti alloys with high-Zr content for biomedical applications  [Not invited]
    7th Materials Science School for Young Scientists (KINKEN-WAKATE 2010)  2010
  • Effect of constitutional phases on unique hardening behavior of dental Ag-Pd-Cu-Au alloys  [Not invited]
    7th Materials Science School for Young Scientists (KINKEN-WAKATE 2010)  2010
  • Heterogeneous α phase precipitation due to micro segregation along vortical structure in biomedical β-type Ti-Nb-Ta-Zr alloy  [Not invited]
    7th Materials Science School for Young Scientists (KINKEN-WAKATE 2010)  2010
  • 生体用Ti-10Cr-X系合金の微細組織と力学的特性に及ぼす応力誘起相変態の影響  [Not invited]
    第32回日本バイオマテリアル学会大会  2010
  • Microstructures and mechanical properties of Ti alloys with high-Zr content for biomedical applications  [Not invited]
    第32回日本バイオマテリアル学会大会  2010
  • TNTZ製脊椎固定用インプラントロッドの力学的特性の改善  [Not invited]
    第32回日本バイオマテリアル学会大会  2010
  • 高強度・高ヤング率Ti-Fe-Cu系合金の設計と均質化処理の影響  [Not invited]
    第120回東北大学金属材料研究所講演会  2010
  • 生体用Ti-10Cr-X系合金の微細組織と力学的特性  [Not invited]
    第120回東北大学金属材料研究所講演会  2010
  • Effect of deformation-induced products on mechanical properties of Ti-Cr alloys for spinal fixture devices  [Not invited]
    第120回東北大学金属材料研究所講演会  2010
  • Microstructures and mechanical properties of metastable Ti alloys with high-Zr content for biomedical applications  [Not invited]
    第120回東北大学金属材料研究所講演会  2010
  • シランカップリング処理によるTi-29Nb-13Ta-4.6Zr合金とセグメント化ポリウレタン複合材料の創出  [Not invited]
    第120回東北大学金属材料研究所講演会  2010
  • スウェージング加工および時効処理を施した生体用β型チタン合金の機械的性質とミクロ偏析の関係  [Not invited]
    第120回東北大学金属材料研究所講演会  2010
  • 次世代航空機用チタン合金の機械的特性に及ぼすレーザー溶接の影響  [Not invited]
    第120回東北大学金属材料研究所講演会  2010
  • 歯科用銀パラジウム金銅合金における溶体化処理後の冷却速度によるミクロ組織と硬さの変化  [Not invited]
    第120回東北大学金属材料研究所講演会  2010
  • 生体用Ti-29Nb-13Ta-4.6Zr合金の力学的特性に及ぼす固溶酸素の影響  [Not invited]
    軽金属学会第119回秋期大会  2010
  • 脊椎固定器具用Ti-Cr合金の力学的特性に及ぼす加工誘起相の影響  [Not invited]
    軽金属学会第119回秋期大会  2010
  • 次世代航空機用α+β型チタン合金溶接材における力学的特性およびミクロ組織の関係  [Not invited]
    軽金属学会第119回秋期大会  2010
  • 高強度・高弾性率Ti-Fe-Cu系合金の設計と力学的特性評価  [Not invited]
    軽金属学会第119回秋期大会  2010
  • Recent development of high mechanical bio-functional metallic biomaterials  [Not invited]
    15th International Metallurgy and Materials Congress (IMMC2010)  2010
  • Effect of high-pressure torsion process on microstructure and mechanical properties of biomedical β-type titanium alloys  [Not invited]
    15th International Metallurgy and Materials Congress (IMMC2010)  2010
  • Negative thermal expansion of cold rolled Ti-29Nb-13Ta-4.6Zr alloy  [Not invited]
    The 1th Joint Workshop on Advanced Materials Research & Application (JWAMRA-1) Dalian University of Technology-Tohoku University  2010
  • Effect of TiB2 or Y2O3 additions on mechanical biofunctionality of Ti-29Nb-13Ta-4.6Zr for biomedical applications  [Not invited]
    Materials Science and Technology 2010 Conference and Exhibition (MS&T'10)  2010
  • シランカップリング処理によるTi-29Nb-13Ta-4.6Zr合金とセグメント化ポリウレタンとの接着性の改善  [Not invited]
    平成22年度秋期（第56回）日本歯科理工学会学術講演会  2010
  • 歯科用銀パラジウム金銅合金における溶体化処理時の冷却速度と特異硬化との関係  [Not invited]
    平成22年度秋期（第56回）日本歯科理工学会学術講演会  2010
  • 高強度・高弾性率Ti-Fe-Cu系合金のミクロ組織と力学的特性  [Not invited]
    日本金属学会2010年秋期(第147回)大会  2010
  • 次世代航空機用α+β型チタン合金溶接材のミクロ組織と力学的特性  [Not invited]
    日本金属学会2010年秋期(第147回)大会  2010
  • Effect of deformation-induced phase on mechanical properties of Ti-xCr alloys for biomedical applications  [Not invited]
    日本金属学会2010年秋期(第147回)大会  2010
  • Effect of severe plastic deformation on microstructure and mechanical properties of β-type Ti-29Nb-13Ta-4.6Zr through high-pressure torsion  [Not invited]
    日本金属学会2010年秋期(第147回)大会  2010
  • Mechanical properties of Ti-30Zr-X (Mo, Cr) alloys for biomedical application  [Not invited]
    日本金属学会2010年秋期(第147回)大会  2010
  • 冷間スウェージング加工後に時効処理を施したTi-29Nb-13Ta-4.6Zr合金の微細組織と力学的特性  [Not invited]
    日本金属学会2010年秋期(第147回)大会  2010
  • 硬質粒子を分散させたTi-29Nb-13Ta-4.6Zr合金のヤング率と疲労強度  [Not invited]
    日本金属学会2010年秋期(第147回)大会  2010
  • 歯科用銀パラジウム金銅合金のミクロ組織と硬さに及ぼす溶体化処理時の冷却速度の影響  [Not invited]
    日本金属学会2010年秋期(第147回)大会  2010
  • 骨再建デバイス用金属系バイオマテリアルの力学的生体機能化  [Not invited]
    日本機械学会2010年度年次大会  2010
  • Change in microstructure and mechanical properties of β-type Ti-29Nb-13Ta-4.6Zr by high-pressure torsion  [Not invited]
    日本機械学会2010年度年次大会  2010
  • Microstructures and mechanical properties of Ti-x binary alloys for biomedical applications  [Not invited]
    日本機械学会2010年度年次大会  2010
  • 加工熱処理によるTi-29Nb-13Ta-4.6Zr合金製ロッドの疲労特性の改善  [Not invited]
    日本機械学会2010年度年次大会  2010
  • チタンへの生体活性ハイブリッド材料コーティング  [Not invited]
    東北大学金属材料研究所ワークショップおよび日本バイオマテリアル学会東北地域講演会「金属系バイオマテリアルの力学的および生物学的生体機能性の付与−骨機能再建・再生マテリアルの創製に向けて−」  2010
  • 生体用α+βおよびβ型チタン合金の疲労強度とミクロ組織の関係  [Not invited]
    東北大学金属材料研究所ワークショップおよび日本バイオマテリアル学会東北地域講演会「金属系バイオマテリアルの力学的および生物学的生体機能性の付与−骨機能再建・再生マテリアルの創製に向けて−」  2010
  • 脊椎固定器具用チタン合金の開発  [Not invited]
    東北大学金属材料研究所ワークショップおよび日本バイオマテリアル学会東北地域講演会「金属系バイオマテリアルの力学的および生物学的生体機能性の付与−骨機能再建・再生マテリアルの創製に向けて−」  2010
  • Aging behavior of β-type Ti-37Nb-3Zr with super-elasticity  [Not invited]
    インターフェイス遠刈田セミナー  2010
  • Effect of Cu content on unique hardening behavior of dental Ag-Pd-Au-Cu system alloy subjected to solution treatment  [Not invited]
    The 7th Pacific Rim International Conference on Advanced Materials and Processing (PRICM 7)  2010
  • Effect of Y2O3 on mechanical properties of Ti-29Nb-13Ta-4.6Zr for biomedical applications  [Not invited]
    The 7th Pacific Rim International Conference on Advanced Materials and Processing (PRICM 7)  2010
  • Effect of oxygen addition on isothermal omega phase stability in Ti-29Nb-13Ta-4.6Zr  [Not invited]
    The 7th Pacific Rim International Conference on Advanced Materials and Processing (PRICM 7)  2010
  • Improvement of mechanical performance and biocompatibility of spinal implant rod made of beta-type Ti-Nb-Ta-Zr alloy  [Not invited]
    The 7th Pacific Rim International Conference on Advanced Materials and Processing (PRICM 7)  2010
  • Negative thermal expansion induced by cold deformation of β-type Ti-alloys  [Not invited]
    3rd international conference & 7th international workshop on Auxetics and related systems  2010
  • Microstructural control of new Ti-Fe-Nb-Zr alloys for biomedical applications  [Not invited]
    第119回東北大学金属材料研究所講演会  2010
  • シランカップリング剤を用いたTi-29Nb-13Ta-4.6Zr合金への生体機能性の付与  [Not invited]
    第119回東北大学金属材料研究所講演会  2010
  • 次世代航空機用チタン合金圧延・鍛造材におけるミクロ組織と力学機能  [Not invited]
    第119回東北大学金属材料研究所講演会  2010
  • 高強度・高弾性率Ti-Fe-Cu系合金の開発  [Not invited]
    第119回東北大学金属材料研究所講演会  2010
  • 生体用Ti-30Nb-xTa-5Zr系合金の応力誘起α"相変態と弾性率の関係  [Not invited]
    第119回東北大学金属材料研究所講演会  2010
  • 応力誘起相変態を利用した生体用Ti-Nb-Ta-Zr系合金の低弾性率化  [Not invited]
    軽金属学会第118回春期大会  2010
  • 次世代航空機用α+β型チタン合金のミクロ組織および力学的特性の関係  [Not invited]
    軽金属学会第118回春期大会  2010
  • 冷間圧延を施したTi-30Zr-xMo (x=5, 6) 合金のミクロ組織および機械的特性  [Not invited]
    軽金属学会第118回春期大会  2010
  • Effect of High-pressure torsion on microstructures and mechanical properties of biomedical β-type titanium alloy  [Not invited]
    軽金属学会第118回春期大会  2010
  • Development of new β-type Ti-Mn alloys with ultra-high strength  [Not invited]
    軽金属学会第118回春期大会  2010
  • 加工熱処理を施したTi-29Nb-13Ta-4.6Zr合金製ロッドの微細組織と疲労特性  [Not invited]
    軽金属学会第118回春期大会  2010
  • Improvement in fatigue property of Ti-29Nb-13Ta-4.6Zr through omega phase precipitation  [Not invited]
    The 1st Workshop on Biomaterials and Applications  2010
  • Research and Development of Low Modulus Titanium Alloys for Implant Applications  [Not invited]
    The 1st Workshop on Biomaterials and Applications  2010
  • 歯科鋳造用金銀パラジウム合金の銅濃度によるアノード分極挙動  [Not invited]
    平成22年度春期(第55回)日本歯科理工学会学術講演会  2010
  • 熱処理プロセスによる歯科精密鋳造Ti-29Nb-13Ta-4.6Zr合金の高力学機能化  [Not invited]
    平成22年度春期(第55回)日本歯科理工学会学術講演会  2010
  • 固溶体化処理による歯科用金銀パラジウム銅合金の特異硬化とミクロ組織の関係  [Not invited]
    平成22年度春期(第55回)日本歯科理工学会学術講演会  2010
  • 各種プロセスによる（Ti, Zr）系金属バイオマテリアルの高力学機能化  [Not invited]
    日本金属学会2010年春期（第146回）大会  2010
  • Design of Low cost Ti-Fe Based Alloys for Biomedical Applications  [Not invited]
    日本金属学会2010年春期（第146回）大会  2010
  • Changes in Microstructures and Mechanical Properties of Ti-29Nb-13Ta-4.6Zr through Severe Plastic Deformation  [Not invited]
    日本金属学会2010年春期（第146回）大会  2010
  • 溶体化処理した歯科用金パラジウム銀銅合金圧延材および急冷凝固材の硬化挙動の変化  [Not invited]
    日本金属学会2010年春期（第146回）大会  2010
  • TiB2およびY2O3微量添加によるTi-29Nb-13Ta-4.6Zr合金の疲労強度改善  [Not invited]
    日本金属学会2010年春期（第146回）大会  2010
  • 冷間加工後に熱処理を施したTi-29Nb-13Ta-4.6Zr合金の微細組織  [Not invited]
    日本金属学会2010年春期（第146回）大会  2010
  • Microstructures and mechanical properties of Ti-30Zr-xMo alloys  [Not invited]
    日本金属学会2010年春期（第146回）大会  2010
  • Mechanical properties of Ti-29Nb-13Ta-4.6Zr with high oxygen content for biomedical applications  [Not invited]
    日本金属学会2010年春期（第146回）大会  2010
  • 局所弾性率上昇型低弾性率チタン合金の開発  [Not invited]
    日本金属学会2010年春期（第146回）大会  2010
  • 患者のために安全で合併症の少ない脊椎固定用インプラント材料の開発  [Not invited]
    第2回博士博・Doctor EXPO'10  2010
  • Effect of oxygen on phase precipitation and mechanical functionality in Ti-29Nb-13Ta-4.6Zr  [Not invited]
    TMS2010 139th annual meeting & exhibition  2010
  • Effect of severe plastic deformation and thermo-mechanical treatments on microstructures and mechanical properties of β-type titanium alloys for biomedical applications  [Not invited]
    18th International Symposium on Processing and Fabrication of Advanced Materials (PFAM XVIII)  2009
  • Mechanical properties of new titanium alloys for spinal fixture application  [Not invited]
    18th International Symposium on Processing and Fabrication of Advanced Materials (PFAM XVIII)  2009
  • Improvement in fatigue properties of spinal implant rod made of Ti-29Nb-13Ta-4.6Zr alloy by cold working and subsequent heat treatments  [Not invited]
    18th International Symposium on Processing and Fabrication of Advanced Materials (PFAM XVIII)  2009
  • Effect of rare earth oxides on mechanical properties of Ti-29Nb-13Ta-4.6Zr alloy for biomedical applications  [Not invited]
    18th International Symposium on Processing and Fabrication of Advanced Materials (PFAM XVIII)  2009
  • Effect of interstitial elements on mechanical performances of Ti-Nb-Ta-Zr alloy for biomedical applications  [Not invited]
    18th International Symposium on Processing and Fabrication of Advanced Materials (PFAM XVIII)  2009
  • Mechanical performances of biomedical (Ti, Zr) system alloys through thermo-mechanical treatments  [Not invited]
    18th International Symposium on Processing and Fabrication of Advanced Materials (PFAM XVIII)  2009
  • Fabrication of calcium phosphate ceramic film on Ti-29Nb-13Ta-4.6Zr using MOCVD technique  [Not invited]
    18th International Symposium on Processing and Fabrication of Advanced Materials (PFAM XVIII)  2009
  • Fatigue properties of dental restorative alloys  [Not invited]
    18th International Symposium on Processing and Fabrication of Advanced Materials (PFAM XVIII)  2009
  • Improvement in fatigue strength of Ti-29Nb-13Ta-4.6Zr alloy by optimizing omega phase precipitation  [Not invited]
    18th International Symposium on Processing and Fabrication of Advanced Materials (PFAM XVIII)  2009
  • Towards developing ubiquitous titanium alloys  [Not invited]
    18th International Symposium on Processing and Fabrication of Advanced Materials (PFAM XVIII)  2009
  • TiB2微量添加によるTi-29Nb-13Ta-4.6Zr合金の疲労強度改善  [Not invited]
    第8回日本金属学会東北支部研究発表大会  2009
  • モノマー含浸重合法により作製した多孔質チタン/生分解性ポリマー複合体の引張および圧縮特性  [Not invited]
    第8回日本金属学会東北支部研究発表大会  2009
  • Relationship between Harding Behavior and Microstructure of Dental Ag-Pd-Cu-Au Alloys with Various Cu/Ag Ratios  [Not invited]
    6th Materials Science School for Young Scientists (KINKEN-WAKATE 2009)  2009
  • Relationship between Mechanical Functionalization and Microstructure of Ti-29Nb-13Ta-Zr through Severe Plastic Deformation  [Not invited]
    6th Materials Science School for Young Scientists (KINKEN-WAKATE 2009)  2009
  • Mechanical properties of Ti-30Zr-xMo alloys for spinal fixture application  [Not invited]
    6th Materials Science School for Young Scientists (KINKEN-WAKATE 2009)  2009
  • TiB2を微量添加したTi-29Nb-13Ta-4.6Zr合金の力学的特性評価  [Not invited]
    第118回東北大学金属材料研究所講演会  2009
  • 表面改質処理を施したZr-20Nb合金の摩擦摩耗特性  [Not invited]
    第118回東北大学金属材料研究所講演会  2009
  • 次世代航空機用α+β型チタン合金のミクロ組織変化と高力学機能化  [Not invited]
    第118回東北大学金属材料研究所講演会  2009
  • Development of Ti-30Zr-xMo alloys for spinal fixture application  [Not invited]
    第118回東北大学金属材料研究所講演会  2009
  • Development of mechanical properties of β-type biomedical titanium alloys by controlling microstructures through HPT processing  [Not invited]
    第118回東北大学金属材料研究所講演会  2009
  • Effect of Cu content on hardening behavior of dental Ag-Pd-Cu-Au system alloy fabricated by liquid rapid solidification method  [Not invited]
    第118回東北大学金属材料研究所講演会  2009
  • 脊椎固定用低弾性率チタン合金製ロッドの曲げ特性  [Not invited]
    第118回東北大学金属材料研究所講演会  2009
  • レアアース微量添加によるTi-29Nb-13Ta-4.6Zr合金の疲労強度改善  [Not invited]
    第31回日本バイオマテリアル学会大会  2009
  • Ti-29Nb-13Ta-4.6Zr合金へのMOCVD法によるリン酸カルシウム膜合成と生体適合性評価  [Not invited]
    第31回日本バイオマテリアル学会大会  2009
  • モノマー含浸重合法による多孔質純チタン/生分解性ポリマー複合体の作製と評価  [Not invited]
    第31回日本バイオマテリアル学会大会  2009
  • 金属系バイオマテリアルの骨類似弾性率化  [Not invited]
    第31回日本バイオマテリアル学会大会  2009
  • Ti-29Nb-13Ta-4.6Zr合金の力学的特性に及ぼすBおよび希土類微量元素の影響  [Not invited]
    軽金属学会第117回秋期大会  2009
  • ω相を利用した生体用チタン合金の高力学機能化  [Not invited]
    軽金属学会第117回秋期大会  2009
  • 脊椎固定器具用新チタン合金の開発  [Not invited]
    軽金属学会第117回秋期大会  2009
  • Ti-29Nb-13Ta-4.6Zr合金のミクロ組織と力学的特性に及ぼす強加工および後熱処理の影響  [Not invited]
    軽金属学会第117回秋期大会  2009
  • 短時間時効処理による歯科鋳造用Ti-29Nb-13Ta-4.6Zr合金の高力学機能化  [Not invited]
    軽金属学会第117回秋期大会  2009
  • MOCVD法を用いたTi-29Nb-13Ta-4.6Zr合金へのハイドロキシアパタイト層合成  [Not invited]
    粉体粉末冶金協会平成21年度秋季大会  2009
  • ω相を利用した生体用Ti-29Nb-13Ta-4.6Zr合金の疲労特性の改善  [Not invited]
    粉体粉末冶金協会平成21年度秋季大会  2009
  • Medical polymer filling into porous titanium fabricated by powder metallurgy and its mechanical functionality  [Not invited]
    EURO PM2009  2009
  • Development of new titanium alloys for spinal fixture rods  [Not invited]
    Interdisciplinary Science of Nanomaterials  2009
  • Effects of severe plastic deformation combined with thermo-mechanical treatments on microstructures and mechanical properties of biomedical β-type titanium alloys  [Not invited]
    Interdisciplinary Science of Nanomaterials  2009
  • 次世代航空機用 α+β 型チタン合金のミクロ組織と高力学機能化  [Not invited]
    日本金属学会2009年秋期（第145回）大会  2009
  • シランカップリング剤を用いたTi−PCL/TCP スキャフォールドの作製と生体適合性評価  [Not invited]
    日本金属学会2009年秋期（第145回）大会  2009
  • 冷間加工および熱処理を用いた脊椎固定用Ti-29Nb-13Ta-4.6Zr製インプラントロッドの力学的特性の改善  [Not invited]
    日本金属学会2009年秋期（第145回）大会  2009
  • MOCVD法を用いて作製したリン酸カルシウム膜合成Ti-29Nb-13Ta-4.6Zr合金の生体適合性評価  [Not invited]
    日本金属学会2009年秋期（第145回）大会  2009
  • Ti-29Nb-13Ta-4.6Zr合金の特異な熱膨張特性の解析  [Not invited]
    日本金属学会2009年秋期（第145回）大会  2009
  • Mechanical properties of Ti-30Zr-xMo alloys for spinal fixture  [Not invited]
    日本金属学会2009年秋期（第145回）大会  2009
  • Effect of oxygen on mechanical performances of Ti-Nb-Ta-Zr alloy for biomedical applications  [Not invited]
    日本金属学会2009年秋期（第145回）大会  2009
  • 大気酸化処理を施した生体用Zr-Nb系合金の摩擦摩耗特性  [Not invited]
    日本金属学会2009年秋期（第145回）大会  2009
  • 種々のプロセスにて作製されたTNTZ合金のミクロ組織と力学的特性  [Not invited]
    日本金属学会2009年秋期（第145回）大会  2009
  • 溶体化処理を施した歯科用銀パラジウム銅金合金の機械的性質  [Not invited]
    日本機械学会2009年度年次大会  2009
  • 生体用Ti-29Nb-13Ta-4.6Zr合金の機械的特性に及ぼすレアアース酸化物の影響  [Not invited]
    日本機械学会2009年度年次大会  2009
  • 酸素含有量の異なる生体用Ti-29Nb-13Ta-4.6Zr合金の機械的性質  [Not invited]
    日本機械学会2009年度年次大会  2009
  • Bending fatigue and spring back properties of implant rods made of β-type titanium alloy for spinal fixture  [Not invited]
    THERMEC’2009  2009
  • Mechanical performances of newly developed titanium and zirconium system alloys for biomedical applications  [Not invited]
    THERMEC’2009  2009
  • Anomalous characteristics of Ti-29Nb-13Ta-4.6Zr alloy for biomedical applications  [Not invited]
    THERMEC’2009  2009
  • Improvement in fatigue strength of Ti-29Nb-13Ta-4.6Zr alloy with keeping low modulus for biomedical applications  [Not invited]
    Materials and Processes for Medical Devices (MPMD) 2009 Conference and Exposition  2009
  • Improvement in mechanical properties of spinal implant rod made of Ti-29Nb-13Ta-4.6Zr  [Not invited]
    Nano/Amorphous Materials and Interface Science Symposium  2009
  • Mechanical Performances of Biomedical Ti and Zr System Alloys through Thermomechanical Treatments  [Not invited]
    Nano/Amorphous Materials and Interface Science Symposium  2009
  • 医療用ポリマーを含浸した多孔質チタンの開発  [Not invited]
    日本バイオマテリアル学会東北地域講演会/東北大学金属材料研究所共同研究ワークショップ「金属系バイオマテリアルの生体機能化−バイオメタルサイエンスの創成に向けて−」  2009
  • Improvement in mechanical properties of implant rod made of biomedical beta type titanium alloy for spinal fusion  [Not invited]
    The third International Conference on Processing, Manufacturing of Advanced Materials (ICAM?3)  2009
  • Improvement in mechanical functionality of biomedical Ti-29Nb-3Ta-4.6Zr with keeping its Young's modulus low  [Not invited]
    The third International Conference on Processing, Manufacturing of Advanced Materials (ICAM?3)  2009
  • Improvement in mechanical properties of dental precision cast Ti-29Nb-13Ta-4.6Zr by microstructural control  [Not invited]
    International Conference on Materials for Advanced Technologies (ICMAT 2009)  2009
  • β型チタン合金のミクロ組織と力学的特性に及ぼす強加工熱処理プロセスの影響  [Not invited]
    軽金属学会第116回春期大会  2009
  • 歯科鋳造用Ti-29Nb-13Ta-4.6Zr合金のミクロ組織制御と高力学機能化  [Not invited]
    軽金属学会第116回春期大会  2009
  • 冷間圧延を施したTi-29Nb-13Ta-4.6Zr合金の集合組織と特異な熱膨張特性  [Not invited]
    軽金属学会第116回春期大会  2009
  • 生体用β型チタン合金製脊椎固定用ロッドの力学的特性に及ぼす冷間加工および熱処理の影響  [Not invited]
    軽金属学会第116回春期大会  2009
  • Effects of severe plastic deformation on microstructure and mechanical properties of biomedical β-type titanium alloy  [Not invited]
    第117回東北大学金属材料研究所講演会  2009
  • 表面改質処理を施した生体用Zr-Nb系合金の機械的性質と摩擦摩耗特性  [Not invited]
    第117回東北大学金属材料研究所講演会  2009
  • Effect of microstructure on mechanical properties of dental Ag-20Pd-14.5Cu-12Au alloy  [Not invited]
    第117回東北大学金属材料研究所講演会  2009
  • MOCVD 法によるTi-29Nb-13Ta-4.6Zr 合金表面へのリン酸カルシウムコーティング膜の作製  [Not invited]
    第117回東北大学金属材料研究所講演会  2009
  • Effects of trace B and Y additions on mechanical properties of Ti-29Nb-13Ta-4.6Zr alloy for biomedical applications  [Not invited]
    第117回東北大学金属材料研究所講演会  2009
  • 歯科精密鋳造したTi-29Nb-13Ta-4.6Zr合金の高力学機能化  [Not invited]
    第117回東北大学金属材料研究所講演会  2009
  • Design and mechanical properties of new titanium alloys for spinal fixture  [Not invited]
    第117回東北大学金属材料研究所講演会  2009
  • Mechanical properties of Ti-29Nb-13Ta-4.6Zr-xO alloy for biomedical applications  [Not invited]
    第117回東北大学金属材料研究所講演会  2009
  • モノマー含浸・重合法による多孔質純チタン/生分解性ポリマー複合体の作製  [Not invited]
    第117回東北大学金属材料研究所講演会  2009
  • 凝固法による市販12%金銀パラジウム合金のミクロ組織の変化  [Not invited]
    平成21年度春期(第53回)日本歯科理工学会学術講演会  2009
  • New β-titanium alloys for biomedical applications  [Not invited]
    日本金属学会春期（第144回）大会 Kim-Jim シンポジウム  2009
  • モノマー含浸・重合法を応用した多孔質純チタンと生分解性ポリマーの複合化  [Not invited]
    日本金属学会春期（第144回）大会  2009
  • 脊椎固定用Ti-29Nb-13Ta-4.6Zr合金製インプラントロッドの曲げ成形性および曲げ疲労特性  [Not invited]
    日本金属学会春期（第144回）大会  2009
  • 加工熱処理プロセスによる生体用β型チタン合金の力学機能性の改善  [Not invited]
    日本金属学会春期（第144回）大会  2009
  • 生体用Zr-Nb系合金の機械的性質と酸化挙動  [Not invited]
    日本金属学会春期（第144回）大会  2009
  • Effects of Mn content on Young's moduli and tensile properties of binary Ti-Mn system alloys for biomedical applications  [Not invited]
    日本金属学会春期（第144回）大会  2009
  • 熱処理プロセスによる歯科鋳造Ti-29Nb-13Ta-4.6Zr合金の高力学機能化  [Not invited]
    日本金属学会春期（第144回）大会  2009
  • B,Y微量添加がTi-29Nb-13Ta-4.6Zr合金の力学的特性に及ぼす影響  [Not invited]
    日本金属学会春期（第144回）大会  2009
  • Ti-29Nb-13Ta-4.6Zr合金へのMOCVD法によるリン酸カルシウム膜合成と生体適合性  [Not invited]
    日本金属学会春期（第144回）大会  2009
  • ω相析出の最適化による低弾性率Ti-29Nb-13Ta-4.6Zr合金の機械的性質の改善  [Not invited]
    日本金属学会春期（第144回）大会  2009
  • Development of Ti-xMn Alloys for Biomedical Applications  [Not invited]
    東北大学グローバルCOEプログラム「材料インテグレーション国際教育研究拠点」若手研究者研究報告会  2009
  • Improvement of mechanical properties of spinal implant rod made of Ti-29Nb-13Ta-4.6Zr alloy by cord working and subsequent heat treatments  [Not invited]
    東北大学グローバルCOEプログラム「材料インテグレーション国際教育研究拠点」若手研究者研究報告会  2009
  • Development of Ti-30Zr-xMo alloys for spinal fixture  [Not invited]
    東北大学グローバルCOEプログラム「材料インテグレーション国際教育研究拠点」若手研究者研究報告会  2009
  • Mechanical Functionalization of Biomedical β Type Titanium Alloys Through Severe Plastic Deformation  [Not invited]
    東北大学グローバルCOEプログラム「材料インテグレーション国際教育研究拠点」若手研究者研究報告会  2009
  • Relationship Between Mechanical Properties and Microstructure of Dental Ag-20Pd-14.5Cu-12 Au Alloy  [Not invited]
    東北大学グローバルCOEプログラム「材料インテグレーション国際教育研究拠点」若手研究者研究報告会  2009
  • Mechanical properties of cast Ti-29Nb-13Ta-4.6Zr alloy subjected to various heat treatments for dental use  [Not invited]
    WPI-AIMR annual workshop  2009
  • Mechanical properties of rod-shaped Ti-29Nb-13Ta-4.6Zr alloy for spinal fixation devises  [Not invited]
    WPI-AIMR annual workshop  2009
  • Effect of heat treatment on mechanical performance of implant rods made of Ti-29Nb-13Ta-4.6Zr alloy for spinal fixture  [Not invited]
    NTU-Tohoku Research Student Workshop on Materials Integration for Health, Energy & Better Environment  2009
  • 生体用チタンおよびジルコニウム系合金の力学的機能性  [Not invited]
    日本機械学会第21回バイオエンジニアリング講演会  2009
  • Effect of silane coupling treatment on mechanical properties of biomedical titanium/polymer composite  [Not invited]
    17th international symposium on processing and fabrication of advanced materials (PFAM XVII)  2008
  • Mechanical biocompatibility of low-modulus beta-type Ti-29Nb-13Ta-4.6Zr in biomedical applications  [Not invited]
    17th international symposium on processing and fabrication of advanced materials (PFAM XVII)  2008
  • Ti-Nb-Ta-Zr系合金の力学的特性に及ぼす強加工熱処理の影響  [Not invited]
    日本鉄鋼協会チタンフォーラム第1回研究発表会/日本金属学会機能性チタン合金研究会第1回講演会  2008
  • Bending properties of implant rods made of Ti-29Nb-13Ta-4.6Zr alloy for spinal fusion  [Not invited]
    5th Materials Science School for Young Scientists (KINKEN-WAKATE 2008)  2008
  • Development of new ubiquitous type titanium alloys for biomedical applications  [Not invited]
    5th Materials Science School for Young Scientists (KINKEN-WAKATE 2008)  2008
  • 生体用低ヤング率Ti-Nb-Ta-Zr系合金におけるω相析出を利用した力学的機能の改善  [Not invited]
    第7回日本金属学会東北支部研究発表大会  2008
  • Anisotropic thermal expansion of plastically deformed beta-type Ti-29Nb-13Ta-4.6Zr alloy  [Not invited]
    第7回日本金属学会東北支部研究発表大会  2008
  • 歯科用銀パラジウム銅金合金のミクロ組織と力学的特性との関係  [Not invited]
    第7回日本金属学会東北支部研究発表大会  2008
  • Development of new ubiquitous type Ti-xMn alloys for biomedical applications  [Not invited]
    第7回日本金属学会東北支部研究発表大会  2008
  • 低弾性率β型チタン合金製脊椎固定用ロッドの力学的生体適合性  [Not invited]
    第116回東北大学金属材料研究所講演会  2008
  • Relationships between alloying elements and HAp formability for Ti-Nb-Ta-Zr system alloy through alkali treatment process  [Not invited]
    第116回東北大学金属材料研究所講演会  2008
  • Anisotropic characteristics of cold rolled β-type titanium alloy  [Not invited]
    第116回東北大学金属材料研究所講演会  2008
  • Relationship between mechanical properties and microstructure of dental Ag-20Pd-14.5Cu-12Au alloy  [Not invited]
    4th international symposium on designing, processing and properties of advanced engineering materials (ISAEM-2008)  2008
  • Mechanical performance of Ti-29Nb-13Ta-4.6Zr applied to spinal implant rod  [Not invited]
    4th international symposium on designing, processing and properties of advanced engineering materials (ISAEM-2008)  2008
  • Anisotropic thermal expansion and microstructure of cold-rolled Ti-29Nb-13Ta-4.6Zr alloy  [Not invited]
    4th international symposium on designing, processing and properties of advanced engineering materials (ISAEM-2008)  2008
  • Thermomechanical treatments for creating superelastic functionality in Ti-29Nb-13Ta-4.6Zr for biomedical applications  [Not invited]
    4th international symposium on designing, processing and properties of advanced engineering materials (ISAEM-2008)  2008
  • 骨折固定モデルを用いた低弾性β型チタン合金の骨吸収抑制能評価  [Not invited]
    日本バイオマテリアル学会シンポジウム2008  2008
  • 低弾性率β型チタン合金の脊椎固定用ロッドへの応用と機械的性質  [Not invited]
    日本バイオマテリアル学会シンポジウム2008  2008
  • Effect of alloying elements on HAp formability of Ti-Nb-Ta-Zr system alloy through alkali treatment process  [Not invited]
    日本バイオマテリアル学会シンポジウム2008  2008
  • Ti-29Nb-13Ta-4.6Zr合金の時効析出および力学的特性に及ぼす酸素添加の影響  [Not invited]
    軽金属学会第115回秋期大会  2008
  • 冷間加工短時間熱処理によるTi-29Nb-13Ta-4.6Zr合金の機械的性質の改善  [Not invited]
    軽金属学会第115回秋期大会  2008
  • Ti-29Nb-13Ta-4.6Zr合金製脊椎固定用ロッドの力学的生体適合性  [Not invited]
    軽金属学会第115回秋期大会  2008
  • Ti-Nb-Ta-Zr系合金の力学的特性に及ぼす強加工および熱処理の影響  [Not invited]
    軽金属学会第115回秋期大会  2008
  • Ti-Ta alloys for biomedical applications  [Not invited]
    The 6th Korea-China symposium on biomaterials and nano-biotechnology  2008
  • Change in mechanical functionality of biomedical Ti-29Nb-13Ta-4.6Zr system alloy through severe working and heat treatment  [Not invited]
    The Korean Institute of Metals and Materials 2008 Fall Conference  2008
  • Mechanical properties of implant rods made of Ti-29Nb-13Ta-4.6Zr for spinal fixture  [Not invited]
    Materials Science and Technology 2008 conference and exhibition (MS&T'08)  2008
  • Improvement in mechanical functionality of porous titanium by biopolymer filling  [Not invited]
    Materials Science and Technology 2008 conference and exhibition (MS&T'08)  2008
  • 生体用ジルコニム・ニオブ系合金の力学的生体親和性  [Not invited]
    日本金属学会秋期（第143回）大会  2008
  • 熱処理した歯科用銀パラジウム銅金合金液体急冷凝固材のミクロ組織と機械的性質  [Not invited]
    日本金属学会秋期（第143回）大会  2008
  • 冷間圧延したTi-29Nb-13Ta-4.6Zr合金の熱膨張特性とミクロ組織の温度依存性  [Not invited]
    日本金属学会秋期（第143回）大会  2008
  • Ti-29Nb-13Ta-4.6Zr合金の冷間圧延単時間時効処理によるω相析出と力学的特性  [Not invited]
    日本金属学会秋期（第143回）大会  2008
  • Ti-29Nb-13Ta-4.6Zr合金の脊椎固定用ロッドへの応用と機械的性質の評価  [Not invited]
    日本金属学会秋期（第143回）大会  2008
  • 生体用Ti-29Nb-13Ta-4.6Zr合金のミクロ組織および力学的特性に及ぼす酸素添加の影響  [Not invited]
    日本金属学会秋期（第143回）大会  2008
  • 液体急冷凝固法により作製された歯科用金銀パラジウム合金の力学的特性の変化  [Not invited]
    平成20年度秋期(第52回)日本歯科理工学会学術講演会  2008
  • 生体用Ti系およびZr系合金の高力学機能化  [Not invited]
    日本バイオマテリアル学会東北地域講演会/東北大学金属材料研究所共同研究ワークショップ「若手バイオマテリアル研究者の研究・開発動向」  2008
  • Mechanical biocompatibility of metallic rods made of low modulus titanium alloy for spinal fixture  [Not invited]
    The 3rd international symposium on nano-bio and amorphous materials  2008
  • Improvement of mechanical biofunctionality of porous titanium by filling medical polymer  [Not invited]
    2nd PNU-IMR joint workshop on advanced and bio materials  2008
  • Evaluation of Ti-29Nb-13Ta-4.6Zr as new spinal implants  [Not invited]
    8th world biomaterials congress (WBC)  2008
  • Mechanical reliability of beta-type titanium alloy, Ti-29Nb-13Ta-4.6Zr, for biomedical applications  [Not invited]
    8th world biomaterials congress (WBC)  2008
  • Titanium alloys composed of nontoxic- and allergy-free elements with high mechanical biocompatibility  [Not invited]
    8th world biomaterials congress (WBC)  2008
  • Effective utilization of space between particles in porous titanium for improving mechanical properties and biofunctionalities using medical polymer filling technique  [Not invited]
    8th world biomaterials congress (WBC)  2008
  • 低弾性率β型チタン合金製脊椎固定用ロッドの機械特性とミクロ組織  [Not invited]
    第115回東北大学金属材料研究所講演会  2008
  • Anomalous thermal expansion behavior of cold rolled biomedical beta-type titanium alloy  [Not invited]
    第115回東北大学金属材料研究所講演会  2008
  • 歯科用低カラット貴金属合金の特異硬化メカニズム  [Not invited]
    第115回東北大学金属材料研究所講演会  2008
  • 医療用高分子を充填した多孔質純チタンの力学的特性に及ぼすシランカップリング処理の影響  [Not invited]
    軽金属学会第114回春期大会  2008
  • アルカリ処理プロセスによる生体用チタン合金へのHAp形成能に及ぼすNb, TaおよびZrの影響  [Not invited]
    軽金属学会第114回春期大会  2008
  • 単純加工短時間時効によるTi-29Nb-13Ta-4.6Zr合金の機械的性質の改善  [Not invited]
    軽金属学会第114回春期大会  2008
  • Ti-29Nb-13Ta-4.6Zr合金製脊椎固定用インプラントロッドのミクロ組織と機械的性質  [Not invited]
    軽金属学会第114回春期大会  2008
  • 歯科用低カラット貴金属合金の特異硬化機構とミクロ組織の関係  [Not invited]
    平成20年度春期(第51回)日本歯科理工学会学術講演会  2008
  • 表面硬化処理を施した生体用β型チタン合金の摩擦摩耗と力学的特性の変化  [Not invited]
    生体−バイオマテリアル高機能インターフェイス科学推進事業（大学間連携研究、東北大学-九州大学）第4回高機能インターフェイス科学カンファレンス  2008
  • 冷間圧延したTi-29Nb-13Ta-4.6Zr合金の熱膨張特性の方位依存性  [Not invited]
    日本金属学会春期（第142回）大会  2008
  • 強加工短時間時効による微細ω相析出を用いたTi-29Nb-13Ta-4.6Zr合金の機械的性質の改善  [Not invited]
    日本金属学会春期（第142回）大会  2008
  • Ti-29Nb-13Ta-4.6Zr合金製脊椎固定用インプラントロッドの機械的性質の評価  [Not invited]
    日本金属学会春期（第142回）大会  2008
  • 医療用高分子を充填した生体用多孔質純チタンの引張および圧縮特性  [Not invited]
    日本金属学会春期（第142回）大会  2008
  • アルカリ溶液処理による高生体適合性金属材料表面へのＨＡｐコーティング  [Not invited]
    日本金属学会春期（第142回）大会  2008
  • Mechanical properties of spinal fixture implant rods made of Ti-29Nb-13Ta-4.6Zr alloy subjected to various heat treatments  [Not invited]
    東北大学グローバルCOEプログラム「材料インテグレーション国際教育研究拠点」若手研究者研究報告会  2008
  • 生体用β型チタン合金の力学機能性の改善  [Not invited]
    日本バイオマテリアル学会東北地域講演会/東北大学金属材料研究所共同研究ワークショップ「バイオマテリアルと再生医療」  2007
  • Characteristics of implanting rods made of Ti-29Nb-13Ta-4.6Zr alloy for spinal fixture  [Not invited]
    4th Materials Science School for Young Scientists (KINKEN-WAKATE 2007)  2007
  • Mechanical reliability of low rigidity titanium alloy for biomedical applications through thermo-mechanical treatments  [Not invited]
    1st asian biomaterials congress (ABMC)  2007
  • Fatigue life and applicability of multi functionally low modulus beta type Ti-29Nb-13Ta-4.6Zr alloy for biomedical applications  [Not invited]
    2nd international conference on mechanics of biomaterials & tissues  2007
  • Plain and fretting fatigue strength of dental low-noble alloys with different microstructures  [Not invited]
    2nd international conference on mechanics of biomaterials & tissues  2007
  • モノマー含浸・重合による多孔質純チタン/ポリメタクリル酸メチル複合体の作製と力学的特性評価  [Not invited]
    第29回日本バイオマテリアル学会大会  2007
  • β安定化元素量を変化させたチタン合金のHAp形成能  [Not invited]
    第29回日本バイオマテリアル学会大会  2007
  • 伸びを改善した歯科鋳造用Co-Cr合金の創製  [Not invited]
    第29回日本バイオマテリアル学会大会  2007
  • 冷間圧延したTi-29Nb-13Ta-4.6Zr合金の熱膨張特性  [Not invited]
    軽金属学会第113回秋期大会  2007
  • 生体用多孔質純チタン/医療用高分子複合体の諸特性  [Not invited]
    軽金属学会第113回秋期大会  2007
  • 種々の加工プロセスにて作製されたTNTZ合金の力学的特性  [Not invited]
    軽金属学会第113回秋期大会  2007
  • NbおよびO添加量を変化させたTi-Nb-Ta-Zr-O系合金の力学的機能性  [Not invited]
    軽金属学会第113回秋期大会  2007
  • Ti-Nb-Ta-Zr系合金のHAp形成能に及ぼす添加元素の影響  [Not invited]
    軽金属学会第113回秋期大会  2007
  • 冷間圧延により制御された生体用β型チタン合金の熱物性  [Not invited]
    第114回東北大学金属材料研究所講演会  2007
  • 整形外科用低弾性率チタン合金製ロッドの機械的性質と生体適合性  [Not invited]
    第114回東北大学金属材料研究所講演会  2007
  • Mechanical behaviors of Ti-29Nb-13Ta-4.6Zr-XO for biomedical applications subjected to cold working and various heat treatments  [Not invited]
    The 6th Pacific Rim International Conference on Advanced Materials and Processing (PRICM6)  2007
  • Hard-ceramic layer formed on Ti-29Nb-13Ta-4.6Zr and Ti-6Al-4V ELI during gas nitriding  [Not invited]
    The 6th Pacific Rim International Conference on Advanced Materials and Processing (PRICM6)  2007
  • Change in tensile and fatigue properties of biomedical Ti-29Nb-13Ta-4.6Zr alloy fabricated by various processings  [Not invited]
    The 6th Pacific Rim International Conference on Advanced Materials and Processing (PRICM6)  2007
  • Development of Porous Titanium Filled with Medical Polymer for Biomedical Applications  [Not invited]
    Iran's 1st international Conference on Biomaterials  2007
  • 生体用多孔質純チタンの引張特性に及ぼす医療用高分子充填の影響  [Not invited]
    粉体粉末冶金協会平成19年度秋季大会  2007
  • モノマー含浸・重合による医療用ポリマー複合型多孔質チタン材料の開発  [Not invited]
    生体−バイオマテリアル高機能インターフェイス科学推進事業（大学間連携研究）第2回高機能インターフェイス科学カンファレンス  2007
  • 生体用Ti-29Nb-13Ta-4.6Zr合金の表面解析と生体機能分子固定化処理  [Not invited]
    表面技術協会第116回講演大会  2007
  • Ti-29Nb-13Ta-4.6Zr合金の表面酸化物組成  [Not invited]
    日本金属学会秋期（第141回）大会  2007
  • アルカリ処理したTi-Nb-Ta-Zr系合金および同合金構成元素のHAp形成能  [Not invited]
    日本金属学会秋期（第141回）大会  2007
  • 医療用高分子を充填した生体用多孔質純チタンの力学的特性  [Not invited]
    日本金属学会秋期（第141回）大会  2007
  • NbおよびO添加量を変化させたTi-Nb-Ta-Zr-O系合金の弾性変形挙動  [Not invited]
    日本金属学会秋期（第141回）大会  2007
  • ガス窒化処理を施した生体用β型チタン合金の疲労強度と表面硬化層  [Not invited]
    日本金属学会秋期（第141回）大会  2007
  • Effect of small change in chemical composition on superelastic behavior of TNTZ for biomedical applications  [Not invited]
    Materials and Processes for Medical Devices (MPMD) 2007 Conference and Exposition  2007
  • Fretting fatigue characteristics and microstructures of dental low noble Ag-Pd-Cu-Au-Zn alloy  [Not invited]
    International Conference on Advanced Technology in Experimental Mechanics 2007 (ATEM'07)  2007
  • Mechanical properties of porous titanium filled with polymethylmethacrylate for biomedical applications  [Not invited]
    International Conference on Advanced Technology in Experimental Mechanics 2007 (ATEM'07)  2007
  • Mechanical performance of biomedical β-Type titanium alloy subjected to surface hardening treatment  [Not invited]
    International Conference on Advanced Technology in Experimental Mechanics 2007 (ATEM'07)  2007
  • Improvement in Mechanical Properties of Porous Titanium by Biomedical Polymer Filling  [Not invited]
    5th International Conference on Porous Metals and Metallic Foams (MetFoam2007)  2007
  • Ti-29Nb-13Ta-4.6Zr合金の特異な熱膨張特性  [Not invited]
    日本金属学会秋期（第141回）大会  2007
  • Highly mechanical functionalization of Ti-Nb-Ta-Zr system alloy for bone reconstruction devices through thermo-mechanical treatments  [Not invited]
    Symposium on the nano particle and highly-functional interface science  2007
  • Development of titanium alloy for mouthpiece of brass instrument and its precision casting process  [Not invited]
    The 11th World Conference on Titanium (Ti-2007)  2007
  • Wear resistance and mechanical properties of biomedical β-type Ti-Nb-Ta-Zr system alloy subjected to gas nitriding process  [Not invited]
    The 11th World Conference on Titanium (Ti-2007)  2007
  • Evaluation of Ti-Nb-Ta-Zr as new medical implants  [Not invited]
    The 11th World Conference on Titanium (Ti-2007)  2007
  • Development of Fabrication Process of Porous Titanium and Polymethylmethacrylate (PMMA) Composite Biomaterial  [Not invited]
    The 11th World Conference on Titanium (Ti-2007)  2007
  • 多孔質純チタンの力学的性質に及ぼす医療用高分子充填の影響  [Not invited]
    軽金属学会第112回春期大会  2007
  • アルカリ処理による生体用α,α＋βおよびβ型チタン合金のHApコーティングと形成能  [Not invited]
    軽金属学会第112回春期大会  2007
  • 生体用多孔質純チタン/医療用高分子複合体の力学的特性  [Not invited]
    第113回東北大学金属材料研究所講演会  2007
  • 生体用β型Ti-Nb-Ta-Zr系合金の変形挙動  [Not invited]
    第113回東北大学金属材料研究所講演会  2007
  • アルカリ処理したTi-Nb-Ta-Zr 系合金のHAp コーティングと生成能  [Not invited]
    日本金属学会春期(第140回)大会  2007
  • チタン合金製金管楽器用マウスピースの特性  [Not invited]
    日本金属学会春期(第140回)大会  2007
  • 歯科用低貴金属合金のフレッティング疲労特性と破壊メカニズム  [Not invited]
    日本金属学会春期(第140回)大会  2007
  • Nb 添加量を微量変化させた Ti-Nb-Ta-Zr 系合金の弾性変形挙動  [Not invited]
    日本金属学会春期(第140回)大会  2007
  • 医療用高分子を充填した生体用多孔質純チタンの開発  [Not invited]
    日本金属学会春期(第140回)大会  2007
  • Mechanically Multifunctional Properties and Microstructure of New Beta Type Titanium Alloy, Ti-29Nb-13Ta-4.6Zr, for Biomedical Applications  [Not invited]
    IMR Workshop on Advanced Materials  2007
  • 生体用Ti-Nb-Ta-Zr系β型チタン合金の物理的特性に及ぼす加工および熱処理の影響  [Not invited]
    日本金属学会春期(第140回)大会  2007
  • Mechanical properties of α+βtype titanium alloys fabricated by metal injection molding with targeting biomedical applications  [Not invited]
    TMS2007 136th annual meeting & exhibition  2007
  • Formability of hydroxyapatite on beta type Ti-Nb-Ta-Zr alloy for biomedical applications through alkaline treatment process  [Not invited]
    The 3rd international symposium on advanced ceramics (ISAC-3)  2006
  • 表面硬化処理を施した生体用β型チタン合金のミクロ組織と力学的特性  [Not invited]
    第112回東北大学金属材料研究所講演会  2006
  • 多孔質純チタンと医療用高分子の複合化プロセスの最適化  [Not invited]
    第112回東北大学金属材料研究所講演会  2006
  • 多孔質純チタンとポリメタクリル酸メチルの複合化技術の開発  [Not invited]
    第28回日本バイオマテリアル学会大会  2006
  • Improvement in wear resistance of beta type titanium alloy for biomedical applications by surface coating of hard layer  [Not invited]
    15th international symposium on processing and fabrication of advanced materials (PFAM XV)/Materials science and technology 2006 conference and exhibition (MS&T'06)  2006
  • Frictional wear characteristics of biomedical Ti-29Nb-13Ta-4.6Zr alloy with various microstructures in air and simulated body fluid  [Not invited]
    The 4th Korea-China symposium on biomaterials and nano-biotechnology  2006
  • Notch fatigue strength and microstructure of Ti-29Nb-13Ta-4.6Zr for biomedical applications  [Not invited]
    The 2nd Korea-Japan joint workshop on biomedical materials  2006
  • Ti-29Nb-13Ta-4.6Zr-XO(X=0.1, 0.2, 0.4 mass%)合金の時効析出と機械的性質  [Not invited]
    日本金属学会秋期(第139回)大会  2006
  • 生体β型チタン合金の力学的特性と生体親和性  [Not invited]
    第111回東北大学金属材料研究所講演会  2006
  • High fatigue strength of Ti-12Cr rod as spinal fixation devices  [Not invited]
    M. Nakai; M. Niinomi; H.H. Liu; K. Narita; O. Takakuwa; H. Soyama
    THERMEC'2016

MISC

  • 共振式平面曲げ疲労試験法による生体用β型チタン合金の疲労特性の評価
    仲井正昭  チタン  69-  238  -241  2021/07
  • 高濃度の固溶酸素を含有したβ型Ti-Nab-Ta-Zr系合金の変形挙動
    仲井正昭; 新家光雄  軽金属学会研究部会報告書No.77「チタンの準安定相・析出相研究部会報告書」  46  -54  2020/10
  • （LMコラム）研究者としての原点回帰
    仲井正昭  軽金属  70-  572  2020
  • （年間レビュー）チタンおよびチタン合金
    仲井正昭; 上田正人; 小林千悟  軽金属  69-  (8)  435  -437  2019/08  [Refereed][Invited]
  • （国際会議便り）第14回チタン世界会議に参加して
    仲井正昭  軽金属  69-  603  -604  2019
  • （年間レビュー）チタンおよびチタン合金
    仲井正昭; 上田正人; 小林千悟  軽金属  68-  (8)  444  -447  2018/08  [Refereed][Invited]
  • 仲井正昭; 上田正人; 小林千悟  軽金属  67-  (8)  401  -404  2017/08  [Refereed][Invited]
  • 新家光雄; 仲井正昭  軽金属  67-  (7)  307  -314  2017/07  [Refereed][Invited]
  • 赤堀 俊和; 新家 光雄; 仲井 正昭  名城大学総合研究所紀要  (21)  145  -148  2016
  • 赤堀 俊和; 新家 光雄; 仲井 正昭  名城大学総合研究所紀要  (20)  241  -244  2015
  • J. Hieda; M. Niinomi; M. Nakai; K. Cho; T. Mohri; T. Hanawa  Materials Science Forum  783-786-  1261  -1264  2014
  • 赤堀 俊和; 新家 光雄; 仲井 正昭  名城大学総合研究所紀要  (17)  91  -94  2012
  • 加工誘起オメガ相変態を利用した新しい脊椎固定用チタン合金の開発
    仲井正昭  チタン,日本チタン協会  60-  (4)  309  2012
  • 第12回チタン世界会議報告書
    仲井正昭  軽金属  61-  583  -584  2011
  • β型Ti-Nb-Ta-Zr系合金中の等温オメガ相安定性に及ぼす酸素添加の影響
    仲井正昭  チタン,日本チタン協会  59-  (4)  307  2011
  • 局所弾性率上昇型脊椎固定用チタン合金製ロッドの開発プロジェクトの概要
    仲井正昭; 新家光雄; 織部一弥; 宮本吾郎; 石本卓也  軽金属 軽金属学会  60-  (7)  342  -344  2010
  • 生体機能化多孔質チタンの開発
    仲井正昭; 新家光雄; 赤堀俊和; 堤 晴美; 大西 隆  チタン  57-  (2)  25  -32  2009
  • 仲井正昭  まてりあ,日本金属学会  46-  (9)  630  -630  2007/09
  • 学会印象記（第11回チタン世界会議（JIMIC5））
    仲井正昭  バイオマテリアル―生体材料―  25-  343  -345  2007
  • 高クロムフェライト鋼の熱処理条件とその耐高温水蒸気酸化性に対する硫黄の有効性
    仲井正昭; 村田純教; 森永正彦  日本学術振興会 耐熱金属材料第123委員会研究報告  44-  (3)  277  -283  2003
  • 不純物Sの微量残存による高Crフェライト系耐熱鋼の耐水蒸気酸化性の改善
    村田純教; 森永正彦; 仲井正昭; 橋詰良吉; 椹木義淳  日本学術振興会 耐熱金属材料第123委員会研究報告  41-  (3)  473  -479  2000

Industrial Property Rights

  • 特許第6621196号:β型強化チタン合金、β型強化チタン合金の製造方法  
    塚原真宏, 遠所茂夫, 三坂佳孝, 仲井正昭, 新家光雄, 成田健吾
  • 特開2019-88203:銀耐性菌又は銀感受性菌の判定方法、及び銀耐性菌又は銀感受性菌の判定キット  2019/06/13
    翠川裕, 月井真郁賀, 仲井 正昭
  • 特許第6406875号:抗菌性検査方法  
    翠川裕, 西野彩水, 仲井正昭, 新家光雄  
    特開2014-239677
  • Spinal Fixation Rod Made of Titanium Alloy
    US 8,425,567 B2
  • 疲労強度に優れた低弾性率の脊椎固定用チタン合金製ロッドの製造方法
    特許第5584898号
  • Spinal Fixation Rod Made of Titanium Alloy
    US 9,034,017 B2

Awards & Honors

  • 2020 軽金属学会第19回軽金属躍進賞
  • 2019 大阪大学接合科学研究所2019年度接合科学共同利用・共同研究賞
  • 2014 第36回日本バイオマテリアル学会大会ハイライト講演
  • 2013 Excellent Graduate Schools 2012 Annual Meeting & Japan-Russia Workshop on Advanced Materials Synthesis Process and Nanostructure Poster Presentation Award
  • 2013 日本歯科理工学会第60回学術講演会発表優秀賞
  • 2013 第125回東北大学金属材料研究所講演会優秀ポスター賞
  • 2012 トーキン科学技術振興財団第22回研究奨励賞
     JPN
  • 2012 日本金属学会第60回論文賞（工業材料部門）
  • 2012 日本鉄鋼協会平成24年度研究奨励賞
  • 2011 International Dental Materials Congress 2011 (IDMC2011) Young Investigator Award
     JPN
  • 2011 東北大学グローバルCOEプログラム「材料インテグレーション国際教育研究拠点」平成22年度若手研究者研究報告会 優秀ポスター賞
  • 2011 日本鉄鋼協会第162回秋季講演大会学生ポスターセッション努力賞
  • 2011 日本金属学会第15回若手講演論文賞
  • 2011 International Symposium of GCOE: Materials Integration Outstanding Poster Presentation for Young Scientists
  • 2010 本多記念会第50回原田研究奨励賞
  • 2010 軽金属学会第28回軽金属奨励賞
  • 2009 東北大学グローバルCOEプログラム「材料インテグレーション国際教育研究拠点」若手研究者研究報告会優秀ポスター賞
  • 2009 日本金属学会春期（第144回）大会優秀ポスター賞
  • 2009 日本歯科理工学会学術講演会発表優秀賞
  • 2009 18th International Symposium on Processing and Fabrication of Advanced Materials (PFAM XVIII) Best poster award
  • 2009 日本金属学会第19回奨励賞（工業材料部門）
     JPN
  • 2008 日本金属学会春期（第142回）大会優秀ポスター賞
  • 2008 第115回東北大学金属材料研究所講演会優秀ポスター賞
  • 2008 第7回日本金属学会東北支部研究発表大会奨励賞（ポスター部門）
  • 2008 5th Materials Science School for Young Scientists (KINKEN-WAKATE 2008) Best poster award
  • 2007 The 11th World Conference on Titanium (Ti-2007) Best poster presentation
     JPN
  • 2007 日本金属学会春期（第140回）大会優秀ポスター賞
  • 2007 第113回東北大学金属材料研究所講演会最優秀ポスター賞
  • 2007 The 11th World Conference on Titanium (Ti-2007) Best poster presentation
  • 2007 第114回東北大学金属材料研究所講演会優秀ポスター賞
  • 2006 第112回東北大学金属材料研究所講演会優秀ポスター賞

Research Grants & Projects

  • 日本学術振興会：科学研究費助成事業 基盤研究(C)
    Date (from‐to) : 2023/04 -2026/03 
    Author : 仲井 正昭
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2021/07 -2024/03 
    Author : 大津 直史
     
    本研究課題では、研究実施者らが発見した「レーザー照射による空気中での金属表面窒化現象」の機序解明を通じて、当該技術の産業への応用可能性を探ることを目的としている。この指針に沿い、令和３年度は、レーザー照射に伴う空気中窒化現象の機序解明に重点を置き研究をおこなった。具体的には、種々金属材料表面に、同一条件（プロセス条件）でレーザ照射をおこない、その表面に形成した皮膜を分析して比較することで、皮膜形成に及ぼす金属材料物性の影響を調べた。 金属材料としては、空気中窒化現象がすでに確認できているチタン材料の他に、ジルコニウム、純鉄および銅を選択した。これら表面に、チタン材料で窒化皮膜形成が確認されている条件にてレーザー照射をおこない、その後に形成した表面皮膜を、Ｘ線光電子分光法、走査型電子顕微鏡、Ｘ線回折法にて調べた。加えて、レーザー照射時に発生するプラズマも分光解析した。 チタン材料の他に、ジルコニウム表面にも、膜厚マイクロの窒化皮膜が形成し、この皮膜は窒化ジルコニウムであることが明らかとなった。純鉄表面にも窒化皮膜は形成したが、その皮膜膜厚は１マイクロ以下と薄く、さらに窒素の含有量は数at％程度でありチタンやジルコニウムと比較して著しく低かった。銅の表面には皮膜形成は全く認められず、窒素の侵入は観察できなかった。 電子顕微鏡像およびプラズマ解析結果から考察すると、チタンおよびジルコニウムでは、レーザー照射に伴い高温プラズマが発生し、これにより金属表面が溶融し、窒化物形成に至ったことがわかった。純鉄でも、高温プラズマの発生および溶融の痕跡が見られたが、表面には窒素が放出された痕跡（脱気の跡）が観察され、このことが窒素の低濃度化の要因になったと推察された。また銅については、溶融の痕跡が小さかった。空気中での窒化皮膜形成は、表面の溶融および窒素の取り込みが重要要素であることがわかった。
  • 難接合材料の逆活用した接合／分離統合技術の確立
    科学技術振興機構：未来社会創造事業
    Date (from‐to) : 2019/04 -2024/03 
    Author : 藤井英俊
  • 日本学術振興会：科学研究費助成事業 基盤研究(B)
    Date (from‐to) : 2020/04 -2023/03 
    Author : 仲井 正昭
     
    骨固定用金属製インプラントの剛性は、骨修復中とその後とで適正値が異なり、骨修復中は高剛性、骨修復完了後は低剛性のほうが適切であることが実験的に示唆されている。さらに、この骨修復状況に依存した金属製インプラントの剛性の適正値の変化は力学的負荷方向に依存し、骨修復中は骨のねじり方向、骨修復後は軸方向の剛性が重要であると考えられる。そこで、本研究では、骨のねじり方向に高剛性であり、軸方向に低剛性となるように、意図的に大きな剛性異方性を付与した金属製インプラントの作製を試みる。この実現のため、材質と形状とを同時に制御することが可能な金属積層造形技術を用いる。昨年度、市販の316Lステンレス鋼を供試材として用い、横方向には高ヤング率となり、縦方向には低ヤング率となるように、面内の直交する二方向の結晶方位を制御し、プレートのヤング率を縦方向よりも横方向に高くすることに成功した。今年度は、結晶構造が体心立方格子（BCC）からなる、市販されていないチタン合金製粉末をガスアトマイズ法およびプラズマ回転電極法を用いて試作し、粒度分布や流動性を評価するとともに、粉末内部のミクロ組織を観察・分析した。その結果、粉末製造法に依存して、各粉末のサテライトの付着状況や真球度が異なっていたが、いずれも金属積層造形に用いることが可能であることを確認した。さらに、粉末内部の気孔の存在割合やデンドライト組織形態が粉末製造法に依存して異なることを明らかにした。ただし、元素分布自体は、いずれの粉末内部においても、BCC安定化元素の濃化部とそれ以外の元素の濃化部とに分かれ、濃化の程度は粉末製造法にあまり依存しないことが明らかとなった。
  • 骨治療に最適化した巨大弾性率異方性 を有する骨固定用金属プレートの開発
    公益財団法人 徳山科学技術振興財団：2020年度研究助成
    Date (from‐to) : 2020/06 -2021/05 
    Author : 仲井正昭
  • 高齢者患者のためにカスタマイズされた低ヤング率チタン合金製脊柱矯正用プリベントロッドの開発
    中小企業庁：戦略的基盤技術高度化支援事業（サポイン）
    Date (from‐to) : 2018/07 -2021/03 
    Author : 株)丸ヱム製作所
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2017/04 -2020/03 
    Author : Endo Hidenori
     
    Using the data obtained from the human cases, we performed computational fluid dynamics (CFD) analysis. We calculated wall shear stress, oscillating shear index, relative residence time of the aneurysm to standardize these parameters. Then, We calculated the appropriate condition to cure the pathology of the aneurysmal wall and to preserve the perforators based on the theory of fluid engineering. We developed the design of the stent which can meet above mentioned condition based on the CFD data. We tried to create prototype stent to deploy into the aneurysm animal model to validate the proper design of the stent.
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2017/04 -2020/03 
    Author : Nakai Masaaki
     
    In the metals with self-tunable elastic modulus developed by us, the elastic modulus is increased at the deformed part by the deformation-induced phase transformation, although low elastic modulus is maintained at the non-deformed part. In this project, as an application of the materials, the possibility of developing mechanical load responsive self-reinforced metallic implants was examined. When strain was systematically changed and applied to the materials, it was confirmed that the deformation-induced phase transformation occurred during elastic deformation. Further, when mechanical load was applied cyclically and then the change in elastic modulus was measured, an increase in the elastic modulus due to such the cyclic mechanical loading was obtained in a part of specimens. These experimental results indicate that the development of mechanical load responsive self-reinforced metallic implants is possible.
  • 「革新的構造材料/耐熱合金・金属間化合物等の開発」における革新的プロセスを用いた航空機エンジン用耐熱材料創製技術開発/次世代合金設計のための要素技術開発の中の「ニアβ型チタン合金鍛造材の力学的特性の異方性」
    内閣府：SIP（戦略的イノベーション創造プログラム）
    Date (from‐to) : 2017/04 -2019/03 
    Author : 仲井正昭
  • 局所変形付与による弾性率自己調整金属製インプラントの高効率強化原理の開拓
    日本学術振興会：科学研究費助成事業 挑戦的萌芽研究
    Date (from‐to) : 2015/04 -2017/03 
    Author : 仲井 正昭
  • Japan Society for the Promotion of Science：Grants-in-Aid for Scientific Research
    Date (from‐to) : 2014/04 -2017/03 
    Author : ENDO Hidenori; SUGIYAMA Shinichiro; NIIZUMA Kuniyasu; NAKAI Masaaki; NAKAGAWA Atsuhiro
     
    Fifteen cases with ruptured vertebral artery dissection admitted to our institution between 2014 and 2016. All the cases were examined by cerebral angiography, and the anatomical morphological features of the dissected segment were analyzed. Furthermore, computational fluid dynamics (CFD) of the dissected segment was assessed, based on the data obtained from cerebral angiography. We studied the appropriate condition to preserve the perforators arising from the dissected segment using the CFD technique. We created the new design of stent in the computer simulation, however, these stents did not apply to the real clinical situation, because there were too many morphological and anatomical variations of the dissected segment.
  • 骨の特異力学機能に学ぶ応力応答性自己強化金属製インプラントの開発原理
    日本学術振興会：科学研究費助成事業 若手研究（A）
    Date (from‐to) : 2013/04 -2017/03 
    Author : 仲井 正昭
  • 骨の力学機能に立脚した脊椎固定用異方性材料デザイン
    日本学術振興会：科学研究費助成事業 基盤研究（A）
    Date (from‐to) : 2012/04 -2016/03 
    Author : 新家光雄
  • 低弾性率チタン合金を用いた骨粗しょう症患者向け脊椎固定器具の開発
    文部科学省：橋渡し研究加速プログラム（シーズB）
    Date (from‐to) : 2014/07 -2015/03 
    Author : 新家光雄
  • 弾性率自己調整金属の国産脊椎固定インプラントへの応用
    文部科学省：橋渡し研究加速プログラム（シーズA）
    Date (from‐to) : 2014/05 -2015/03 
    Author : 仲井 正昭
  • 新規パルスジェットメスによる胸腔鏡下反回神経機能温存手術の研究
    日本学術振興会：科学研究費助成事業 挑戦的萌芽研究
    Date (from‐to) : 2013/04 -2015/03 
    Author : 宮田剛
  • 生体用弾性率自己調整金属の応力応答性自己強化－応力誘起オメガ相に秘められた可能性
    日本学術振興会：科学研究費助成事業 挑戦的萌芽研究
    Date (from‐to) : 2013/04 -2015/03 
    Author : 仲井 正昭
  • パルスジェットメスによる内視鏡的治療技術の応用開発
    日本学術振興会：科学研究費助成事業 基盤研究（C）
    Date (from‐to) : 2012/04 -2015/03 
    Author : 中野徹
  • 非平衡プロセスによる超軽量・高耐食性多目的Ti-Mg合金の創製
    日本学術振興会：科学研究費助成事業 挑戦的萌芽研究
    Date (from‐to) : 2012/04 -2014/03 
    Author : 新家光雄
  • 弾性率自己調整金属を応用した脊椎固定器具の開発
    科学技術振興機構：復興促進プログラム（A-STEP）探索タイプ
    Date (from‐to) : 2012/10 -2013/09 
    Author : 仲井 正昭
  • 局所弾性率上昇型脊椎固定用チタン合金製ロッドの開発
    新エネルギー・産業技術総合開発機構：産業技術研究助成事業（若手研究グラント）
    Date (from‐to) : 2009/07 -2013/06 
    Author : 仲井 正昭
  • 高次生体適合性を有する生体用β型チタン合金創出のためのプロセスデザイン
    日本学術振興会：科学研究費助成事業 若手研究（B）
    Date (from‐to) : 2011/04 -2013/03 
    Author : 仲井 正昭
  • チタン合金の生体適合表面加工プロセス開発
    科学技術振興機構：震災地域を対象とした「研究シーズ探索プログラム」
    Date (from‐to) : 2011/07 -2012/03 
    Author : 仲井 正昭
  • 高分子複合化技術を用いたテクスチャ生体用β型チタン合金の人工腱への応用
    日本学術振興会：科学研究費補助金 挑戦的萌芽研究
    Date (from‐to) : 2009/04 -2012/03 
    Author : 新家光雄
  • 歯科用低カラット貴金属合金の特異強化メカニズムの解明とその応用
    日本学術振興会：科学研究費補助金 基盤研究（B）
    Date (from‐to) : 2009/04 -2012/03 
    Author : 新家光雄
  • 変形部分の特性を制御した脊椎固定用チタン合金製ロッドの開発
    日本鉄鋼協会：鉄鋼研究振興助成
    Date (from‐to) : 2009/04 -2011/03 
    Author : 仲井 正昭
  • 脊椎固定用高加工硬化性チタンロッドの開発
    財団法人 スズキ財団：科学技術研究助成
    Date (from‐to) : 2009/04 -2010/03 
    Author : 仲井 正昭
  • 医療用ポリマー充填による生体機能化多孔質チタンの作製と特性評価
    財団法人 材料科学研究助成基金：研究助成金
    Date (from‐to) : 2008/04 -2009/03 
    Author : 仲井 正昭
  • チタン系バイオマテリアルの特異な熱物性による新機能化
    日本学術振興会：科学研究費補助金 若手研究（スタートアップ）
    Date (from‐to) : 2006/04 -2008/03 
    Author : 仲井 正昭
  • 湿潤環境での耐熱鋼の高温酸化と水素侵入
    財団法人 谷川熱技術振興基金：研究助成金
    Date (from‐to) : 2006/10 -2007/03 
    Author : 仲井 正昭

Committee Membership

  • 2014 -2018   日本金属学会チタン製造プロセスと材料機能研究会   委員   日本金属学会チタン製造プロセスと材料機能研究会
  • 2011 -2014   日本金属学会会報編集委員会   委員   日本金属学会会報編集委員会
  • 2010 -2014   軽金属学会東北支部   幹事   軽金属学会東北支部
  • 2013   日本金属学会東北支部   支部幹事   日本金属学会東北支部
  • 2013   日本鉄鋼協会東北支部   支部幹事   日本鉄鋼協会東北支部
  • 2008 -2012   日本金属学会機能性チタン合金研究会   委員   日本金属学会機能性チタン合金研究会

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