ABSTRACT
Shape memory alloys (SMAs), such as Ni-Ti (Nitinol) alloy, have a smaller hysteresis of (austenite Û martensite) phase transformation than that in steel [1]. Th ere are numerous papers that have examined SMAs. Th is is because SMAs are scientifi cally attractive and can be used as sensors and actuators. Th e phase transformation in SMAs is reversible and usually can be characterized by the latent heat and the change of lattice parameters. To obtain reversible deformation, a heating or cooling device is usually incorporated. SMAs also have been used extensively as key actuator materials with applications in aerospace structures (such as chevron) and medical implant devices (such as stent), where temperature or stress is a driving force to obtain large strain recovery (shape memory eff ect [SME]) or large “elastic” strain (superelastic behavior).
