J. Phys. IV France 112 (2003) 761
DOI: 10.1051/jp4:2003993

Shape memory characteristics of cold drawn Ti-Ni wires

Y. Xu¹, K. Otsuka², H. Yoshida¹, H. Nagai¹, R. Oishi¹, H. Horikawa³ and T. Kishi<sup>4

1</sup>  SSRC, National Institute of Advanced Industrial Science and Technology, 1-1-1 Umezono, Tsukuba 305-8568, Japan
²  National Institute for Materials Science (NIMS), Advanced Materials Laboratory, 1-1 Namiki, Tsukuba 305-0044, Japan
³  Furukawa Techno. Material Co. Ltd., 5-1-8 Higashi-yawata, Hiratsuka, Kanagawa 254-0016, Japan
⁴  National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047, Japan

Abstract
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.

© EDP Sciences 2003