Processing, microstructure and thermomechanical behavior of superelastic nickel-titanium thin films sputter-deposited at elevated temperatures.

摘要

ear-equiatomic NiTi is capable of fully recoverable strains associated with the formation and reversion of a stress-induced martensite phase from a B2 (CsCl) parent phase. Recently, sputter-deposited NiTi thin films have drawn attention for potential application to microactuators in microelectromechanical systems(MEMS). As-sputtered NiTi films are amorphous when deposition temperature is below 0.4;A series of NiTi films were sputter deposited at various substrate temperatures between 573 K and 773 K using a Ni;A fully crystallized NiTi film could be produced at a deposition temperature of 623 K which is about 150 K lower than the minimum temperature to form B2 phase by post-deposition annealing in a reasonable time. Crystalline films displayed microstructures consisting of very fine columnar B2 grains with 0.1-0.3