Fabrication of TiNi shape memory alloy thin films by pulsed-laser deposition

Thin films of TiNi shape memory alloy have been prepared by pulsed-laser deposition at different substrate temperatures. The stoichiometry and crystallinity of the deposited films as functions of the substrate temperature were investigated. The deposition rate, surface morphology, crystallization temperature, and phase transformation behavior of the films were studied. It was found that both the substrate temperature and the laser fluence play important roles in the composition control and crystallization of the films. The deposition rate is of the order of 10(-2) nm/pulse. The Ni content ranges from 46.7 to 52.0 at.%. The crystallization temperature of the amorphous Ti-51.5 at.% Ni films is around 460 degreesC. The activation energy of the crystallization process was determined by Kissinger's method to be 301 kJ/mol. The martensitic transformation temperature of the annealed Ti-51.5 at.% Ni film was determined to be -20.8 degreesC.