Effects of pressure on the generalized stacking fault energy and twinning propensity of face-centered cubic metals

Abstract

The effects of pressure on the generalized stacking fault energies (GSFE), core structure of dissociated dislocation, twinning propensity and phase stability are comprehensively investigated by molecular statics simulations and first principles calculations in three typical face-centered cubic (FCC) metals, Cu, Ag and the equiatomic CoCrFeMnNi high-entropy alloy (HEA). It demonstrates that the pressure has an important impact on the morphology of GSFEs in Cu, Ag and the CoCrFeMnNi HEA. In contrast to the slight improvement of twinning propensity in Cu, a substantial enhancement of twinning propensity is caused by high pressures in Ag and the CoCrFeMnNi HEA. The first principles calculation indicates that the dependence of stacking fault energy and the relative stability of FCC and HCP phases on the pressure dictates the sensitivity of twinning propensity to the pressure in FCC metals. The results not only shed new light on the pressure effects on the twinning propensity, but also have an important implication on the manipulation of deformation mechanisms and mechanical properties in FCC metals.