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Effects of Thermally Induced Cyclic γ ↔ ε Transformation on Shape Memory Effect of a Quenched FeMnSiCrNi Alloy

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  • The authors would like to thank financial support from the National Natural Science Foundation of China (nos. 51171123, 50971095, and 50871072) and the Natural Science Foundation for Young Scientists of Sichuan Province in China (no. 2010A01-436).

Abstract

The effects of thermally induced cyclic γ ↔ ε transformation on microstructures and shape memory effect (SME) are investigated in a quenched Fe14Mn5.5Si8.0Cr5.0Ni alloy. The results show that the annealing at 773 K remarkably improves the SME in the quenched alloy. One thermal cycling between 290 and 773 K remarkably increases the SME, but the further thermal cycling hardly improves the SME. The reason is that the amount of thermal ε martensite remarkably reduces after annealing at 773 K, but it hardly changes with the further increase of thermal cycling between 290 and 773 K. The pre-existing thermal ε martensite not only prevents the occurrence of stress-induced ε martensitic transformation but also promotes the formation of α′ martensite.

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