Shape memory materials

Compared with piezoelectric ceramics and magnetostrictive materials, the shape memory materials possess larger recoverable strain and recovery stress but slower response to external field. It is expected that the magneto shape memory materials may develop considerable strain as well as rapid and precise shape control. Pseudoelasticity and shape memory effect (SME) resulted from martensitic transformation and its reverse transformation in shape memory materials were generally described. The requirements of appearing the shape memory effect in materials and the criteria for thermoelastic martensitic transformation were given. Some aspects concerning characteristics of martensitic transformation, and factors affecting SME in Ni Ti, Cu Zn Al and Fe Mn Si based alloys as well as ZrO 2 containing ceramics were briefly reviewed. Thermodynamic calculation of M s temperature as function of grain size and parent ordering in Cu Zn Al was presented. The works on prediction of M s in Fe Mn Si based alloys and in ZrO 2 CeO 2 were mentioned. Magnetic shape memory materials were briefly introduced. [