| Co-Investigator(Kenkyū-buntansha) |
ENDO Shoichi Osaka University Research Center for Extreme Materials Professor, 極限物質研究センター, 教授 (10001843)
YE Jinghua National Research Institute for metals Division of Surface and Interface Nationa, 金属材料技術研究所, 特別研究員 (90230630)
NAKATA Yoshiyuki Osaka University The Institute of Scientific and Industrial Research Research As, 産業科学研究所, 助手 (40164214)
KAKESHITA Tomoyuki Osaka University The Institute of Scientific and Industrial Research Research As, 産業科学研究所, 助手 (90127209)
TADAKI Tsugio Osaka University The Institute of Scientific and Industrial Research Associate P, 産業科学研究所, 助教授 (90029885)
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| Budget Amount *help |
¥7,400,000 (Direct Cost: ¥7,400,000)
Fiscal Year 1991: ¥2,500,000 (Direct Cost: ¥2,500,000)
Fiscal Year 1990: ¥4,900,000 (Direct Cost: ¥4,900,000)
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| Research Abstract |
We have investigated the effect of hydrostatic pressures on martensitic transformations in non-invar Ti-51at%Ni shape memory alloys aged for a long time and a short time and in invar Fe-29.9at%Ni, assuaged Fe-31.9Ni-9.8Co-4. lTi (at%) and Fe-24. Oat%Pt alloys, the last alloy having different degrees of order (S 0, S>O, S 0.6, S 0.8), by carrying out electrical resistivity measurements under hydrostatic pressures up to 1.5GPa and optical microscopy observation. As a result, it was found that the hydrostatic pressure dependence of transformation temperatures measured for invar alloys was not in good agreement with the one calculated by using a Patel-Cohen's equation, although it was in good agreement for non-invar alloys. It was, then, speculated that the disagreement for the invar alloys might be caused by the existence of spontaneous volume magnetostriction, s, which is one of physical properties related to the invar nature. Then, a new equation including the term due to s has been der
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ived to estimate the hydrostatic pressure dependence of transformation temperature by referring to the Parel and Cohen's equation. In order to evaluate the newly derived equation unknown physical quantities involved in the equation, s and the volume change associated with the martensitic transformations for Fe-Ni and Fe-Pt (S 0.6, S 0.8) alloys, have been obtained by magnetization measurements under a hydrostatic pressure and x-ray diffraction experiments with a cold stage, respectively. The pressure dependence of transformation temperatures for those invar alloys has then been calculated by putting the measured physical quantities and the known ones, such as the bulk modulus and Gibbs chemical free energy, into the newly derived equation. Consequently, the calculated dependence for the invar alloys was in all good agreement with the measured one in the measured hydrostatic pressure range. It was, thus, concluded that the speculation as to the effect of spontaneous volume magnetostriction and the derived equation were quantitatively confirmed to be appropriate, optical microscopy observation showed that morphology of the martensities formed in the Fe-Ni alloy under hydrostatic pressure was the same as that of thermallymartensites irrespective of the formation temperature. This result is consistent with that in Fe-Ni-C alloys previously examined by the present authors. Less
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