Role of stacking faults in martensite transformation of FeMnSiCrNi shape memory alloy subjected to plastic deformation at high temperatures

FeMnSiCrNi shape memory alloy (SMA) undergoes plastic deformation at high temperatures, including 850, 900, 950 and 1000 degrees C. All the deformed FeMnSiCrNi samples consist of gamma austenite and epsilon martensite, where the orientation relationship between gamma austenite and epsilon martensite is [110](gamma)//[(2110) over bar](epsilon). Furthermore, epsilon martensite increases with increasing deformation temperature. Stacking faults play a predominant role in martensite transformation of FeMnSiCrNi SMA. The mechanisms of martensite transformation are revealed based on slip of Shockley partial dislocation as well as formation of intrinsic and extrinsic stacking faults. The critical transformation stress of FeMnSiCrNi SMA is further put forward based on stacking fault energy. Quenching stress plays an important role in martensitic transformation of FeMnSiCrNi SMA.