Martensitic transformations and thermal expansion behaviors of structural heterogeneous NiTi alloys

Martensitic transformation characteristics of NiTi shape memory alloys after severe cold deformation were studied. By designing the shape of the original surface curve, distinct macroscopic domains with different dislocation densities were introduced into the NiTi alloys, and materials possessing the characteristics of composites were obtained. Due to the interactions between the deformation structure and martensite variants, the reverse transformation temperature range was significantly enlarged. One of the possible applications for these materials is the so-called temperature memory effect in a wide temperature range.