Development of heterogeneous-nanostructured Ti with high strength and low elastic modulus for medical treatment

2022 Fiscal Year Final Research Report

• Project/Area Number: 20H00305
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Medium-sized Section 26:Materials engineering and related fields
• Research Institution: Toyohashi University of Technology
• Principal Investigator: Hiromi Miura 豊橋技術科学大学, 工学(系)研究科(研究院), 教授 (30219589)
• Co-Investigator(Kenkyū-buntansha): 下川 智嗣 金沢大学, 機械工学系, 教授 (40361977) ; 渡邊 千尋 金沢大学, 機械工学系, 教授 (60345600) ; 青柳 吉輝 東北大学, 工学研究科, 准教授 (70433737)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: チタン / 超微細粒組織 / 多軸鍛造 / 強度 / 生体材料 / 弾性率

Outline of Final Research Achievements

Pure Ti was multi-directionally forged at room temperature employing various pass strains Δε from 0.2 to 0.8 and forging strain rates from 1.0×10-3 s-1 to 1.0×10-2 s-1. In the all MDFing conditions, grains were gradually fragmented with increasing cumulative strain of MDFing. The forging stress increased more rapidly when the pass strain became larger, and the hardness also increased accordingly. Nevertheless, failure tended to take place more easily with increasing pass strain. When examined the evolved microstructure, it was found that grain fragmentation looked more proceeded with increasing pass strain and strain rate. Tensile strength was gradually increased with cumulative strain and superior mechanical properties of tensile strength about 0.95 MPa were attained. By low temperature annealing, the tensile strength was further increased to 1.1 GPa. Then, the Young's modulus decreased down to 80 GPa.

Free Research Field

金属材料

Academic Significance and Societal Importance of the Research Achievements

生体材料として広く利用されているチタン・チタン合金だが，チタン合金はVなどの添加元素が様々な問題を引き起こすことが報告されている．一方で，より生体適合性に優れる純チタンは，強度がチタン合金に比べて低く，用途が限定される．本研究の成果は，純チタンの結晶粒の超微細化によって，強度がチタン合金と同等になることが示され，生体適合性に問題があるチタン合金の代替材として様々な部位への利用の可能性を示すことができた．