Cracking of NiTi Thin Films Deposited on Cu Substrate

Abstract

This study has investigated the cracking of Ti-51.45at.%Ni thin films deposited on Cu substrate. An analysis is presented that relates the crack spacing and the Vickers microhardness values to the strain in the film. Tensile tests are carried out on CSS-44100 electron universal testing machine. The strain rate is 1.1 × 10-4 s-1. The average crack spacing is obtained using scanning electron microscopy (SEM). The Vickers microhardness values are determined by Everone MH-6 microhardness tests. The results have showed that a series of parallel cracks grew in the film and the cracks are equally spaced. The minimum crack spacing is about 87 μm. The mean crack spacing is dependent on the tensile strain in the film. The crack spacing decreases as the film elongation increases. The Vickers microhardness values increase as the film elongation increases.