A theoretical investigation on deformation behavior and phase prediction of CoCrFeNi-based high entropy alloys

Abstract

In this paper, deformation behaviors (slip and twinning phenomena) for CoCrFeNi-based high entropy alloys with various alloying elements (Nb, Ta, Zr, V, W and Pd) have been efficiently investigated via rigidly shifting an FCC supercell at (111) plane along [112¯] direction, performing first-principles approach. This study provides a new insight accompanying an advantageous framework in order to design CoCrFeNi-based high entropy alloys through calculation of generalized stacking fault energy parameters, dislocation mediated slip and twinning propensities, the Rice-criterion and etc. It revealed that dislocation mediated slip and martensitic transformation are favored through addition of Pd element to CoCrFeNi high entropy alloys, while incremental rates of Ta, Nb, Zr, V and W elements increase the propensity of mechanical twining formation. Furthermore, phase prediction (volume fraction of face centered cubic and/or body centered cubic crystals) of selected HEAs was determined, showing inaccuracy of Valence Electron Concentrations (VEC) approach and thus brings a novel perspective on strength-ductility behavior. The electron density difference and density of states concerning electronic properties of HEAs were also estimated, explaining why and how alloying elements affect phase prediction.