The Effect of Cold Working Ratio for Fatigue Life of Ti-Ni-Cu Shape Memory Alloy

Abstract

The shape memory alloy (SMA) is well known as functional material, and drawn attention to apply to various fields such as medical, engineering and so on. However for the farther extension of the SMA applications, it is necessary to improve functions and fatigue life. In generally, the method of hardening with cold working is treated to metal for improving the fatigue life. In this paper, the thermo-mechanical cyclic test for Ti-41.7 Ni-8.5 Cu SMA samples with different cold working ratio (10-40%) are examined, and the effect of cold working ratio on fatigue life is investigated. And the observations of fatigue fracture surface are carried out. As the result of this examination, it becomes clear that the fatigue life Ti-Ni-Cu SMA under the condition of thermo-mechanical cycles decrease with increasing of cold working ratio.