| Project/Area Number |
15560600
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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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 |
SATO Akikazu Tokyo Institute of Technology, Materials Science and Engineering, Professor, 大学院・総合理工学研究科, 教授 (20089824)
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| Co-Investigator(Kenkyū-buntansha) |
KUMAI Sinji Tokyo Institute of Technology, Materials Science and Engineering, Associate Professor, 大学院・総合理工学研究科, 助教授 (00178055)
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| Project Period (FY) |
2003 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 2004: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2003: ¥2,100,000 (Direct Cost: ¥2,100,000)
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| Keywords | FeMnSi / shape memory alloy / fcc / hcp phase transformation / high strength material / pseudo elasticity / χ-phase / HVEM / thin foil compression / Fe-Mn-Si / fcc【tautomer】hcp相変態 / 高強度合金 / 疑弾性 / 硬いbcc相 |
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| Research Abstract |
It is over 20 years since FeMnSi is found to show a good shape memory effect(SME) by γ【tautomer】ε martensitic transformation. The SME is improved significantly in comparison with the SMA observed in stainless steel single crystals by avoiding formation of a phase. This is due to the difficulty of the non-basal slip in the ε phase, especially in absence of the additional ε→α transformation. After accumulation of sufficient knowledge, a hybrid alloy of FeMnSiCr was used as a pipe joint in tunnel construction for the first time in the world in 2003. The recovery strength of the alloy used was in the range 150〜200 MPa. The present study was started to improve the strengthening of the SMA further by means of beating and heating, and succeeded to increase the recovery strength to the level as high as 450 MPa by introduction of hardly deformable domains. The subject was extended to clarify its contribution to the pseudo elasticity. Dispersion of the hardly deformable domains apparently increased the internal stress as well as the pseudo elasticity. The latter contributes to the dumping energy in vibration. The hardly deformable phase contributing to the strengthening is identified to be a bcc based ordered structure of I 4^^-3m by means of ZOLZ and FOLZ diffraction analyses and is the one called x -phase. This phase itself is found to be not deformable over a few GPa by the present semi-in-situ compression experiments. It is, thus, confirmed that the FeMnSi based SMA can be strengthened significantly by such a dispersion hardening which balances against the chemical force due to the phase change.
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