Effect of Pd content on crystallization and shape memory properties of Ti-Ni-Pd thin films

Abstract

The Pd content dependence of the crystallization process of Ti-Ni-(19.1-35.3)Pd (at. %) thin films fabricated by a sputter-deposition method was investigated. Ti-Ni-(19.1-26.1)Pd (at. %) as-deposited thin films were found to be amorphous, whereas Ti-Ni-(29.1-35.3)Pd (at. %) thin films were crystalline in the as-deposited condition. Both the crystallization temperature and activation energy for the crystallization of the amorphous thin films decrease with increasing Pd content. The shape memory effect was confirmed in the in situ crystallized thin film. The finer grain size in the in situ crystallized thin film results in a higher critical stress for slip and a smaller recovery strain when compared with the thin film crystallized by post annealing. ? 2011 Taylor & Francis.