Thermodynamic analysis of the martensitic transformation in NiTi—II. Effect of transformation cycling

Abstract The effect of transformation cycling, with and without applied stress, on the martensitic transformation in NiTi has been studied. Changes in transformation temperatures resulting from cycling are interpreted in terms of changes to the elastic strain energy and the irreversible energy associated with the transformation. It is found that the main effect of thermal cycling under zero stress is to increase the elastic strain energy. With pseudoelastic cycling and extensive thermal cycling under stress the elastic strain energy decreases with increasing cycling due to the development of a directional internal stress field associated with the formation of aligned variants.