Dependence of equilibrium stacking fault width in fcc metals on the γ-surface

Abstract

A phase field dislocation dynamics model that can model widely extended dislocations is presented. Through application of this model, we investigate the dependence of equilibrium stacking fault width (SFW) on the material γ-surface in fcc metals. This phase field model includes a direct energetic dependence on a parametrization of the entire γ-surface, which is directly informed by density functional theory. A wide range of materials are investigated and include both very low stacking fault energy (SFE) materials, such as silver, and high SFE materials, such as palladium. Additionally, analysis shows that by accounting for the unstable stacking fault energy, γU, we can better describe the material dependence of the equilibrium SFW rather than using only the intrinsic SFE, γI. Specifically, we see a direct dependence of the stable SFW between partial dislocations on the energy difference (γU − γI), which describes the energy barrier that partial dislocations must overcome in order to widen the stacking fault.