Constitutive behavior and microstructural evolution of FeMnSiCrNi shape memory alloy subjected to compressive deformation at high temperatures

Abstract

Constitutive behavior and microstructural evolution of FeMnSiCrNi shape memory alloy (SMA) subjected to compressive deformation at high temperatures were investigated based on the different deformation conditions. According to Arrhenius type equation, the constitutive equation of FeMnSiCrNi SMA was constructed according to strain compensation, where material parameters vary with increasing strain. The involved constitutive equation can effectively predict the flow stress during dynamic recrystallization (DRX) of FeMnSiCrNi SMA. All the compressed FeMnSiCrNi samples consist of ε martensite and γ austenite. In addition, dislocations, stacking faults and austenite twins were also found in the deformed FeMnSiCrNi samples. Owing to the occurrence of DRX, the grain size increases with increasing deformation temperature. Furthermore, with increasing deformation temperature, the fraction of large angle grain boundaries increases while the one of low angle grain boundaries decreases. Deformation temperature also affects the texture of FeMnSiCrNi SMA. With increasing deformation temperature, 〈110〉 texture becomes weak gradually in the γ austenite, but 〈001〉 texture and cube texture are intensified gradually along with the onset of 〈110〉 and 〈111〉 fiber textures. Moreover, ε martensite possesses 112¯2 fiber texture. Keywords: Shape memory alloy, FeMnSiCrNi alloy, Constitutive behavior, Microstructure evolution, Plastic deformation