INFLUENCE OF CRYSTALLIZATION TEMPERATURE ON PHASE TRANSFORMATION IN Ti-RICH NiTi THIN FILMS
(1.Department of Materials Science,
2.Information Storage Research Centre,ShanghaiJiao Tong University, Shanghai200030, P. R. China)
2.Information Storage Research Centre,ShanghaiJiao Tong University, Shanghai200030, P. R. China)
Abstract: The effects of crystallization annealing temperature on phase transformation temperature and SME of Ti-rich NiTi thin films prepared by the magnetron-sputtering system were studied. The experimental results showed that the phase transformation sequence of Ti-rich NiTi thin films were P→R→M for cooling transformation, and R→P and M→P for heating one, while increasing the annealing temperature from 823K to 1 103 K, theR-phase transformation temperature TP-R and TR-P were nearly unchanged, the martensitic transformation temperatures, however, moved to higher temperature. A thin film with room temperature micro-structure consisting of almost wholeR-phase can be obtained by annealing at appropriate temperature (e.g. at 923 K), which possesses a stable transformation temperature, narrow hysteresis and a good SME. It is suitable for the application to the micro-machine elements.
Key words: NiTi alloy film crystallization phase transformation