Cold Rolling-Induced Multistage Transformation in Ni-Rich NiTi Shape Memory Alloys

Abstract

A multi-stage transformation (MST) has been observed in cold-worked Ti–50.3 at%Ni shape memory alloy by differential scanning calorimetry (DSC). When thickness reduction reaches about 5% strain, the phenomenon is able to occur in 50.3 at%Ni alloy. The multi-stage transformation behavior is due to interior microstructure variation, i.e., texture formation and defects aggregation which caused localized stress fields and affected the phase transformation behavior.