Shape memory characteristics of cold drawn Ti-Ni wires

With the aim of the applications for smart composite, the influence of cold drawing on the shape memory effect and mechanical properties of Ti-49.5at%Ni and Ti-50at%Ni was investigated systematically. It was found that the reverse transformation temperatures increased significantly, while the martensitic transformation temperatures decreased with increasing amount of cold drawing. Both the temperature range for reverse and martenistic transformations became larger with increasing amount of cold drawing. A recovery strain above 2% and a recovery stress up to 300MPa can be obtained in cold drawn wires. A two-way shape memory effect was observed in as-cold drawn TiNi wires. These results indicate that cold drawn TiNi wires have many unique shape memory properties which can be applicable for smart composites.