Stacking fault energy of basal plane for hexagonal closed-packed medium entropy alloy ZrHfTi: Ab initio prediction

Ternary alloy ZrHfTi is a novel hexagonal close-packed medium entropy material. As a fundamental parameter for understanding the deformation behavior and mechanical property especially ductility, the stacking fault energy (SFE) of basal plane for ZrHfTi alloy has been studied. Unlike the case of CrCoNi-based alloys, the derived SFEs for intrinsic and twin-like stacking faults of alloy ZrHfTi are relatively high. From the evolution features of stacking fault energies from unitary to binary and ternary materials, the SFEs of studied alloys are intermediate between component materials due to merely mixing effect. Because the SFEs of the constituent elements are relatively large, the SFEs of multicomponent alloys are not necessarily small. The SFE of ZrHfTi is obviously affected by alloying of constituent elements with strong structural propensity. Based on the generalized stacking fault energy, mechanical properties and deformation characteristics are further studied. Our results demonstrate that ZrHfTi has good ductility and high yield strength, and deformation twin in ZrHfTi is also very possible based on the twinning criteria. The research of this paper is beneficial for the design and development of more valuable high-performance multicomponent alloys.