EFFECT OF HEAT TREATMENTS ON THE MICROSTRUCTURE AND TRANSFORMATION CHARACTERISTICS OF TiNiPd SHAPE MEMORY ALLOY THIN FILMS

摘要

Microstructure and phase transformation behaviors of the film annealed at different tempera- tures were studied by X-ray diffractometry (XRD), transmission electron microscopy and differ- ential scanning calorimeter (DSC). Also tensile tests were examined. For increasing annealed temperature, multiple phase transformations, transformations via a B19-phase or direct marten- site/austenite transformtion are observed. The TiNiPd thin film annealed at 750°C had relatively uniform martensite/austenite transformtion and shape memory effect. Martensite/austenite trans- formtion was also found in strain-temperature curves. Subsequent annealing at 450°C had minor effect on transformation temperatures of Ti-Ni-Pd thin films but resulted in more uniform trans- formation and improved shape memory effect.