Overview of the development of shape memory and superelastic alloy applications

Abstract

This chapter introduces the historical overview of the application developments for shape memory and superelastic alloys in Japan. The history of applications of shape memory and superelastic alloys in Japan can be divided into four periods as follows. The first period began in 1981 and continued until 1985; main applications in this dawn period were toys and coil springs for home electronics. The second period began with the application of Ti–Ni shape memory alloys for bra wires in 1986. This sensational product attracted attention and made the alloys popular in Japan, and was followed by various applications for apparel, accessories and eyeglass frames. The third period started in 1992 with the application of superelastic Ti–Ni wires as antennas for mobile phones. The fourth period began in 2001 and continues to the present. Applications of superelastic alloys have been exploited in a number of medical devices since 2001. Shape memory wires and coil springs have been applied as actuators in automobiles and ecologic products. The developments of novel shape memory alloys, such as high temperature shape memory alloys and Ni-free shape memory alloys, and advanced fabrication technologies will further accelerate and expand applications of shape memory alloys.