Dependency of grain boundary dislocation network configuration on generalized stacking fault energy surface in FCC metals

Abstract

We use a microscopic phase-field (MPF) model, incorporating the generalized stacking fault energy (GSFE) surfaces (i.e., the γ-surface) as inputs, to investigate systematically the evolution of dislocation network configurations at low-angle pure twist grain boundaries (GBs) in six face-centered cubic (FCC) metals (Ag, Cu, Rh, Ir, Pd and Pt) that have different GSFE surfaces. The equilibrium configurations of GB dislocation networks are obtained via the interplay between the crystalline energy and the elastic strain energy during the energy minimization process. It was found that for {111} twist GBs, though the geometrically necessary dislocations (GNDs) of the screw type are observed, they can be either full or partial ones depending on the GSFE surfaces of the above metal systems. The areas of the staking faults regions formed between partial dislocations are quantitatively characterized as a function of the magnitude of the stacking fault energy, the elastic modulus and the GB misorientation angle. A fast-acting model for predicting the geometric characteristics of the GB dislocation networks is developed based directly on the material properties and GB misorientation, which is validated by its applications to another two metal systems (Au and Ni) with the same GB.