PULSED-LASER DEPOSITION OF NITI SHAPE-MEMORY ALLOY THIN-FILMS WITH OPTIMUM PARAMETERS

A series of experiments was carried out to optimize the pulsed laser d eposition parameters for the fabrication of high quality NiTi shape me mory alloy thin films. Smooth NiTi shape memory alloy thin films were deposited at high growth rate with optimum deposition parameters bused on the analysis of the relationships among the morphology of the targ et surface and the deposited thin film, the laser energy, the target-s ubstrate distance, the thin film composition and its growth rate. Crys tal structures and phase transformation temperatures of the annealed N i-Ti-49.7(50.3) thin film were characterized by using X-ray diffractio n and differential scanning calorimetry, respectively. The martensitic transformation temperature of the crystallized Ni49.7Ti50.3 thin film is found to be lower than room temperature and 27 degrees C lower tha n that of the NiTi target material. These results are attributed to th e refined grain size of the thin film and its composition, which devia tes slightly from Ni50Ti50. (C) 1998 Elsevier Science S.A. All rights reserved.