Abstract
The heat treatment effect on transformation properties of a NiTi Shape Memory Alloy (SMA) film is discussed. TiNi SMA films were deposited by using sputter deposition techniques, and were then solution-treated and aging-treated. The phase transformation properties were investigated by means of a differential scanning calorimeter (DSC), X-ray diffractometer and a transmission electron microscope (TEM). As sputtered film had an amorphous structure with fluctuating density of titanium atoms. The films solution-treated at 600°C and aging-treated at 400°C had several kinds of phases. The rhombohedral phases, austenite phases and amorphous phases could be distinguished within the same film. The film solution-treated at 800°C and aging-treated at 400°C showed the largest enthalpy of the transformation and had the preferable crystalline structure. The samples solution-treated at 1000°C, in which NiTi were resolved partially into Ti2Ni and Ni4Ti3 were more brittle.
