Multiple-stage strain hardening due to the deformation-induced martensitic transformation in additively manufactured high-entropy alloy

This study investigates microstructural changes and the presence of multiple stages in strain hardening ratio (SHR) resulting from the sequential occurrence of deformation-induced martensitic transformation (DIMT) during the tensile deformation of an additively manufactured ferrous medium entropy alloy (AMed-FeMEA). The inherent microstructural heterogeneity in AMed-alloys contributes to distinctive deformation mechanisms and instantaneous hardening behavior at varying strain levels. To comprehensively address this phenomenon, a semi-empirical constitutive model is presented that associates multiple stages in SHR with the occurrence rate of DIMT. The model demonstrates its applicability by characterizing tensile deformation of AMed-FeMEA at both room temperature and liquid nitrogen temperature.