Size Effects on the Martensitic Phase Transformation in Ti54.5Ni45.5 Alloy Thin Films

Abstract Ti 54.5 Ni 45.5 alloy nonorganic thin film was prepared by direct current (DC) magnetron sputtering system and subsequent rapid annealing treatment. Electrical resistivity(ER), X-ray diffraction (XRD) and transmission electron microscope (TEM) were carried out to investigate martensitic phase transformation behaviour and microstructure. The results demonstrated that the grains of the thin film can be refined through increasing heating rate, the smaller grain size is, the lower martensitic phase transition temperature. The martensitic phase transformation and its reversible phase transition were observed as the grain size was 50 nm, which was smaller than the critical dimension (60 nm) of recent theoretical predictions. In addition, the martensitic variant mainly showed the single-pair morphologies with (001) compound twinning.