Effect of deformation by stress-induced martensitic transformation on the transformation behaviour of NiTi

摘要

It has been reported that martensite innear-equiatomic NiTi is thermally stabilised after amoderate deformation via martensit reorientation.This work continues the study by investigating theeffect of deformation via stress-induced martensitictransformation on the transformation behaviour of thealloy. It was observed that the stress-inducedmartensite was also stabilised relative to the thermalmartensite formed on cooling, as indicated by anincrease in the critical temperature for the reversetransformation. Associated with the stabilisation,the heat effect, as determined by differentialscanning calorimetry, and the temperature interval ofthe reverse transformation, were measured and foundto decrease with increasing level of deformation. Theexperimental results also demonstrated that thestress-induced martensitic transformation wasmicroscopically localised, as expected for a first-order phase transformation.