Grain Boundary Mediated Dislocation Behavior in a 2D Bi-Crystal: A Model Atomistic Study

The deformation behavior of a bi-crystal metallic sample is studied using a two-dimensional atomistic approach. The primary objective is to gain fundamental insight into the dislocation plasticity mediated by a grain boundary. The molecular statics simulations utilize displacement-control led simple shearing of a bi-crystal model. In most cases an initial point defect is included in the crystal lattice for triggering dislocation formation. Within the present modeling framework, the dislocation activity can be easily visualized and correlated with the overall load-displacement response of the material. It is observed that the same grain boundary can be both a sink and a source of dislocations. Mechanical actions alone can lead to the formation of grain boundary ledge (capable of nucleating dislocations) and even a dramatic change in grain boundary geometry. Qualitative features of dislocation-grain boundary interaction and strengthening mechanisms observed from the modeling are discussed.