Effect of precipitates on phase transformation behavior of Ti-49 at.% Ni film

Ti-49 at.% Ni thin films developed by magnetron sputtering were annealed un der different conditions. Two types of precipitates, the FCC Ti2Ni and HCP TiNi3, were found to exist simultaneously in the annealed films. Their size , distribution and morphology can be strongly affected by the annealing con ditions. The phase transformation behavior was recorded by a standard d.c. method. The martensitic transformation temperatures of annealed films were much lower than those reported for TiNi films, which may possibly be explai ned by the small size of grains and precipitates, the close distance betwee n precipitates and the orientation of some TiNi3 precipitates. With the int ensification of annealing conditions, the martensitic transformation temper ature was increased. The changed size and distribution of precipitates were used to explain this tendency. (C) 1999 Elsevier Science S.A. All rights r eserved.