Effects of deformation-induced martensitic transformation on quasi-static and dynamic compressive properties of metastable SiVCrMnFeCo high-entropy alloys

High-entropy alloys (HEAs) utilizing a deformation-induced martensitic transformation (DIMT) mechanism have been developed as they exhibit an excellent balance of strength, ductility, and toughness. Investigations on deformation behaviors under dynamic responses are essential for their wide and reliable cryogenic applications; however, the effects of DIMT on mechanical properties under dynamic and cryogenic environments have hardly been studied yet, especially in metastable HEAs. In this study, compressive properties of two SiVCrMnFeCo alloys having different initial microstructure and stability of face-centered-cubic (FCC) against the DIMT were investigated under both quasi-static and dynamic loadings and at room and cryogenic temperatures. Under dynamic loading, the extent of DIMT was reduced than that under quasi-static loading due to the increased adiabatic heating, which increased the stability of FCC and suppressed the DIMT behavior. Nevertheless, the activated DIMT with decreasing stability of FCC due to the increased Si content and the decreased test temperature enhanced overall compressive properties. However, the interrupted dynamic compressive test results showed that the shear localization and the formation of adiabatic shear band (ASB) were promoted as the martensite formed more by the DIMT, concurrently resulted in the deterioration of resistance to shear cracking. These findings suggest that the delicate control of stability of FCC would be significant in wide and effective applications of the metastable alloys toward cryogenic or dynamic environments.