Transformation and Mechanical Properties of TiNi Thin Films Sputter Deposited at Various Argon Pressures for Micromachine Actuators
Seiji Shimizu and Katsutoshi Kuribayashi
Faculty of Engineering, Yamaguchi University, 2-16-1 Tokiwadai, Ube, Yamaguchi 755-8611, Japan
We studied the transformation and mechanical properties of Ti- 54.8-51.6 at % Ni shape memory alloy thin film actuators sputter-deposited at different argon pressures of 0.47-3.4 Pa. The higher the argon pressure, the lower the nickel composition. TiNi thin films were crystallized at 800C for 10min, aged at 400C for 6h, and analyzed by differential scanning calorimetry and tensile tests. All films showed 2-step transformation of martensite, R, and austenite phases. The maximum generative stress of 365MPa was obtained when the TiNi thin film actuator deposited at 2.0Pa was heated electrically to 30A/mm2 after deformation of 3.0% at room temperature.
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