Factors influencing the reversion of stress-induced martensite to austenite in a Fe-Mn-Si-Cr-Ni shape memory alloy

It is well-known that one way shape memory effect (SME) in Fe-Mn-Si based shape memory alloys (SMAs)  is related to the thermally-induced reversion of ε (hexagonal close packed, hcp) stress induced martensite (SIM) to γ (face centered cubic , fcp) austenite. In the case of a Fe-Mn-Si-Cr-Ni SMA this reverse martensitic transformation was analyzed  in regards to the critical temperature for the beginning of austenite formation (A_s) and the percentage of permanent deformation recovered by heating (SME). For this purpose, a dilatometric study, dynamic mechanical analyzer (DMA) measurements and scanning electron microscopy (SEM) observations were employed aiming to determine a relationship between permanent strain, ε SIM, A_s and SME.