Shape memory materials
(School of Materials Science and Engineering, Shanghai Jiaotong
University,Shanghai 200030, P.R.China)
University,Shanghai 200030, P.R.China)
Abstract: 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 generallydescribed. 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 ZrO2containing ceramics were briefly reviewed. Thermodynamic calculation of Ms temperature as function of grain size and parent ordering in Cu-Zn-Al was presented. The works on prediction of Ms in Fe-Mn-Si based alloys and in ZrO2CeO2 were mentioned. Magnetic shape memory materials were briefly introduced.
Key words: shape memory materials; Ni-Ti; Cu-Zn-Al；Fe-Mn-Si；martensitic transformation; thermoelastic transformation; magnetic shape memory materials