Influence of aging on microstructure, martensitic transformation and mechanical properties of NiTiRe shape memory alloy

Abstract

Aging is an effective way to adapt the microstructure, phase transformation and consequently the mechanical properties of NiTi shape memory alloys. In the present study, Ni52Ti47.7Re0.3 shape memory alloy was solution treated at 1000°C for 24 h then aged at various temperatures of 300, 400, 500 and 600°C for 3 h. The influence of aging treatment on microstructure, martensitic transformation and mechanical properties of Ni52-Ti47.7Re0.3 was investigated. The microstructure of the solution treated alloy was martensite as a matrix phase and precipitates of Ti2Ni phase. The aged alloys had a microstructure as same as that of solution treated alloy in addition to the existence of other types of precipitates like Ni4Ti3 and Ni3Ti. The martensitic -austenitic transformation during heating and cooling was going through one stage of transformation. The martensitic phase transformation temperature increased by the increase of aging temperature but still lower than that of solution treated alloy.

Aging Effect on Microstructure and Machinability of Corrax Steel

“…This austenite formation is the result of an uncompleted transformation of austenite into martensite. The aging process causes an inverse transformation from martensite to austenite [34,35], while similar results were reported for Corrax [36,37]. The solution heat treated sample (A0) has less than 2% retained austenite [38].…”