Modeling of grain boundary transmission, emission, absorption and overall crystalline behavior in Σ1, Σ3, and Σ17b bicrystals

A dislocation-density grain–boundary (GB) interaction scheme for face-centered cubic bicrystals with three coincident site lattice boundaries was developed to account for the interrelated dislocation-density interactions of GB emission, absorption, and transmission. The proposed GB scheme was coupled to a dislocation-density multiple-slip crystalline plasticity formulation and specialized finite-element algorithms to account for behavior on the microstructural scale. A conservation law for dislocation densities was also used to balance dislocation-density absorption, transmission, and emission within the GB region. The predictions indicated that GB absorption increases are due to increases in immobile dislocation densities in high-angle GBs without coplanar slip planes and collinear slip directions, such as Σ17b. Low-angle GBs with coplanar slip planes and collinear slip directions are characterized by high transmission rates and insignificant GB dislocation-density accumulations. GB processes such as emission, absorption, and transmission are directly related to microstructural behavior and can be potentially controlled for desired material response.