Review on phase transformation behavior of NiTi shape memory alloys

Abstract

Formulating and instigating of shape memory alloys (SMAs) is an emerging field in aerospace and biomedical firms due to its tremendous chattels such as shape memory effect (SME) and super elasticity (SE). Memorizing ability of shape memory material in retaining its deformed shape is influenced by these unique properties. The phase changing processes are executed by the forward and reverse transformation such as cubic austenite to monoclinic martensite and vice-versa. Phase transformation temperatures (As, Af, Ms and Mf) are decided the range of phase limit. The state of phase presented in NiTi-SMA such as austenite or martensite is decided the application. Therefore, controlling the microstructure of NiTi alloy through amendment of transformation temperatures is a challenging mission in today materials advancement. The amendment as per required application is executed mainly in two ways such as by changing the chemical composition of NiTi alloy and heat treatment process. This investigation starts from changes in microstructure, transformation temperature and mechanical properties by these two different alteration processes. Short review of this investigation is intended to give self-consistent and logical key issues on shape memory alloys from metallurgical viewpoint on an up-do-date basis. Aftermath of this investigation exhibited a flawless knowledge for selecting the route through which phase transformation behavior can improve for NiTi-SMA.