Identification of optimized Ti–Ni–Cu shape memory alloy compositions for high-frequency thin film microactuator applications

Ti–Ni–Cu shape memory thin films within a broad composition range were investigated by the cantilever deflection method using combinatorial methods. Optimal compositions with improved functional properties, i.e. large recovery stress, high transformation temperatures, low thermal hysteresis width and small temperature interval of transformation, were identified using a newly defined figure of merit. Of the investigated alloys, Ti50Ni41Cu9 and Ti45Ni46Cu9 exhibit the best shape memory properties for compositions showing a and a -phase transformation, respectively.