Fatigue and adhesion properties of martensite and austenite phases of TiNi shape memory thin films deposited by magnetron sputtering

The application area of TiNi shape memory thin film is gradually increasing. Especially MEMS applications of TiNi film, such as micro-mirror, micro-pump and micro-actuator are widely used. Adhesion to the substrate and fatigue resistance of these films is particularly important for these applications. In this study, we investigated adhesion and fatigue properties of martensite and austenite phases of TiNi shape memory thin films. TiNi films were deposited on copper and Si wafers with magnetron sputtering. Structural properties of the films were determined via SEM, XRD and EDS analyses. Adhesion and fatigue properties of the films were investigated through progressive and multi-pass scratch tests. Phase transformation temperatures and hysteresis were observed with differential scanning calorimeter (DSC). Scratch test results showed that adhesion and fatigue resistance of austenite phase of TiNi film is higher than martensite phase.