| Project/Area Number |
11650679
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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 |
Physical properties of metals
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| Research Institution | Toyohashi University of Technology |
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Principal Investigator |
TSUCHIYA Koichi Toyohashi University of Technology, Associate Professor, 工学部, 助教授 (50236907)
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| Co-Investigator(Kenkyū-buntansha) |
UMEMOTO Minoru Toyohashi University of Technology, Professor, 工学部, 教授 (90111921)
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| Project Period (FY) |
1999 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥3,000,000 (Direct Cost: ¥3,000,000)
Fiscal Year 2000: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1999: ¥2,300,000 (Direct Cost: ¥2,300,000)
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| Keywords | shape memory alloys / spinodal decomposition / martensitic transfomation / two-way shape memory effect / anti-ferromagnetic transition / 電気抵抗 / 形状記憶効果 |
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| Research Abstract |
The γ phase in Mn-Cu alloy, which is disordered fcc solid solution, transforms martensiticaly to fct. This transformation is a weak first order type and suitable for the use in actuator application with precise control. This γ phase is in a metastable state ; the heat treatment at 700 K leads to the spinodal decomposition into Mn-rich and Mn-depleted zones. In the present study the effect of the decomposition on shape memory behavior was investigated.
Alloy ingots of Mn-15at%Cu were made by high frequency induction furnace or arc melting ; they were hot/cold rolled to the thickness of 0.2 mm and then homogenized at 1173 K.Isothermal aging was done at 673 K using a salt bath.
Transformation temperatures were measured by DSC and electrical resistivity. Changes in the lattice parameter were measured by X-ray diffraction. To characterize the shape memory behavior of the alloy, a sample was heat treated at 1173 K for 1800 s and aged at 673 K under constrain onto the inner surface of a ceramic cylinder of 15 mm radius and quenched. It was then flattened at room temperature(corresponding to 0.7% deformation). Shape change of the sample was recorded during heating/cooling cycles to 493K.
The following results were obtained :
1)Martensitic transformation temperatures siginificantly increase by the aging at 673 K.The change in transformation temperature was proportional to the decrease in the resistivity. Their correlation can be well explained by a thermodynamic model which takes the compositionaly heterogenous structure as a results of spinolda decomposition into account.
2)The shape recovery before the aging was about 30% : it increased to 50% by the aging for 10^5s. The aged sample exhibited two way memory of about 30%. This behaivor may be explained by that the antiferromagnetic spin arrangements remain even after the reverse transformation to the fcc phase.
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