Recent developments in the research of shape memory alloys

Most of shape memory alloys are functional intermetallics. They are now practically being used for couplings, actuators, medical guide wires etc., and are hopeful candidates for smart materials, which already exist. In the present paper, recent developments within nearly 10 years on shape memory alloys and martensitic: transformations, on which shape memory effect and superelasticity are based, were concisely reviewed. Since Ti-Ni alloys are the best practical shape memory alloys, we mostly discussed on the alloys, but we discussed more general problems as well. Furthermore, we discussed the ductility and density of point defects in intermetallics, since they are important problems in intermetallics in general. At the end we introduced some recent applications of shape memory alloys briefly.