| Project/Area Number |
17360334
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Structural/Functional materials
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
HOSODA Hideki Tokyo Institute of Technology, Recision and Intelligerce Laboratory, Associate Professor (10251620)
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| Co-Investigator(Kenkyū-buntansha) |
WAKASHIMA Kenji Tokyo Institute of Technology, Precision and Intelligence Laboratory, Professor (70016799)
IMAMURA Tomonari Tokyo Institute of Technology, Precision and Intelligence Laboratory, Assistant Professor (60361771)
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| Project Period (FY) |
2005 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥16,330,000 (Direct Cost: ¥15,400,000、Indirect Cost: ¥930,000)
Fiscal Year 2007: ¥4,030,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥930,000)
Fiscal Year 2006: ¥5,000,000 (Direct Cost: ¥5,000,000)
Fiscal Year 2005: ¥7,300,000 (Direct Cost: ¥7,300,000)
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| Keywords | biomedical shape memory alloy / titanium alloy / microstructure / mechanical properties / texture / superelasticity / thermomechanical treatment / cold rolling / 金属物性 / 結晶工学 / 格子欠陥 / 形状記憶合金 |
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| Research Abstract |
The purpose of this research is to clarify the relationships among microstructures, defects and mechanical properties of Ni-free biomedical shape memory alloys, especially TiNbAl alloys, through thermo-mechanical treatments to introduce high-energy and high-density lattice defects by severe deformations. In order to enhance their superelastic properties, material strengthening to increase critical stress for slip deformation is effective and this was tried by severe deformations of cold rolling up to 99% in reduction thickness and rapid solidification. Firstly, the formation of texture and superelastic deformation were investigated using Ti-26Nb-3A1 alloy with relatively low martensitic transformation temperatures. It was found that the development of deformation texture is strongly related to true strain and that the texture is rapidly grown after when the true strain becomes over 3. Although the grain size after the solution treatment is coarse around 500μm, the grains become fine an
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d needle-like shape elongated with the rolling direction. Then, the development of recrystallization texture was investigated with various cold rolling reductions. It was found that the development of recrystallization texture is strongly dependent on reduction rate, and that different textures are developed. {001}_β<110>_β type texture is formed when cold rolling reduction is lower than 90%, and further increasing cold rolling reduction, the texture formed is changed to {112}_β<110>_β type. {001}_β<110>_β type exhibits less anisotropy in superelasticity than {112}_β<110>_β, resulting that {001}_β<110>_β type texture is more useful for practical applications. Secondly, the texture formation of α" and α"+β type TiNbA1 alloys was investigated. It was found that deformation and recrystallization textures are {112}_β<110>_β type and {111}_β<110>_β for the α"+β alloy, respectively. Besides, deformation and recrystallization textures of α" alloy are {223}_<α"><302>_<α"> type and {011}_<α"><311>_<α"> for the α" alloy, respectively. Therefore, the type of texture formation as well as superelasticity strongly depends on the type of stable phase in the TiNbAl alloys. Similar results were obtained for the cold rolled wires. Finally, the rapid solidification was done for Ti-24Nb-3A1 but neither texture nor fine grains were formed even though the high energy process of the rapid solidification. It is conclude that texture and superelastic properties of the titanium alloys can be controlled through a proper thermomechanical treatment combined with severe deformation. Less
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