Clarification of interaction between peculiar mechanical phenomena and constitutional elements in biomedical beta-type titanium alloy with high oxygen content

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K05139
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 26040:Structural materials and functional materials-related
• Research Institution: Meijo University
• Principal Investigator: Niinomi Mitsuo 名城大学, 理工学部, 特任教授 (50126942)
• Co-Investigator(Kenkyū-buntansha): 赤堀 俊和 名城大学, 理工学部, 准教授 (00324492)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: β型チタン合金 / 酸素 / 力学的特性 / 強度 / 延性 / ヤング率

Outline of Final Research Achievements

The Ti-42Nb-xO alloy showed a good elongation of 15% and a tensile strength of over 850 MPa even at high oxygen concentrations. In addition, it was confirmed that the yield phenomenon occurs in this alloy system alloy when the oxygen concentration becomes high (0.7 mass%). This is one of the peculiar phenomena in which a similar phenomenon occurs in the TNTZ alloy when the oxygen concentration becomes high. It was found that the yield point observed only in high oxygen content TNTZ alloys became obscured in tensile tests at high temperature and high strain rate. Therefore, it is considered that the yield point phenomenon is caused by fixation of dislocations by solid solution oxygen.

Free Research Field

生体材料学

Academic Significance and Societal Importance of the Research Achievements

高酸素濃度Ti-Nb合金にて高強度・高延性が得られることを見出したことは、低コストで生体為害性の指摘が無く、かつ地球上に豊富に存在する酸素を合金元素に用いた高強度・高延性低コストチタン合金の開発に繋がり、チタン合金の高コスト化が可能でチタン合金の汎用に貢献できる。また、高濃度酸素TNTZ合金で発現する特異現象の一つである降伏点現象が酸素と転位との相互作用であることを明確化したことは、学術的意義が高く、さらにはチタン合金における転位と酸素との相互作用を制御することで高強度・高延性チタン合金の開発が可能であることを示唆している。