Stabilization of deformed stress-induced martensite and its effect on shape memory effect in an Fe-Mn-Si-Ni-Co alloy

As the Fe-25.6Mn-5.1Si-4.1Ni-1.8Co(wt%) shape memory alloy is prestained at -80 C, the recovery strains increase rapidly with the increase of prestrains, and at last it reaches a constant value. The reverse transformation temperature rises also with the increase of prestrains. Microstructure analysis indicates that the stress-induced martensite is usually plastically deformed and stabilized. This stabilization of the stressinduced martensite is an important reason for lower recovery strains in the polycrystalline Fe-Mn-Si alloys. finally, the characteristics of stabilization and possible way to prevent it are also discussed.