The effect of cyclic tensile loading on the stress-induced transformation mechanism in superelastic NiTi alloys: an in-situ X-ray diffraction study

The effect of cyclic tensile loading on the transformation behavior of superelastic NiTi was investigated by in-situ synchrotron X-ray diffraction (XRD) and transmission electron microscopy (TEM). It was quantitatively demonstrated that cyclic tensile loading alters the reversible austenite-martensite transformation character from localized (transformation fronts propagating) to uniform. TEM and XRD showed that the change of transformation behavior is not related to the presence of retained martensite or a change in texture upon tensile load-cycling but to the introduction of dislocations.