Martensitic transformation and two-way shape memory effect of sputter-deposited Ni-rich Ti–Ni alloy films

The martensitic transformation and the associated two-way shape memory effect of sputter-deposited Ni-rich Ti–Ni alloy films were investigated. For the investigation of the effect of aging (without constraint) on the martensitic transformation behavior, deposited amorphous films were crystallized and at the same time aged by holding at various temperatures between 673 and 823 K. Differential scanning calorimetry (DSC) was performed on these specimens. For the investigation of the effect of aging on the spontaneous shape change associated with the transformations, the amorphous films were crystallized by holding at 973 K and then aged under constraint (circular shapes) at several different temperatures between 673 and 793 K. For these specimens, the spontaneous shape change during cooling and heating was observed.