Parametric atomistic analysis of dislocation-interface interactions in thin metallic films

The dislocation behavior in thin metallic crystals is studied using molecular statics simulations. Attention is directed to corroborating the overall film response and the nano-scale defect mechanisms, in particular, the interaction between dislocations and interfaces. The two-dimensional numerical model consists of atoms of the metallic film having a close-packed crystal structure. The substrate is not explicitly included but special displacement constraints are imposed on the boundary atoms, which are conceived to be the interface layer adjacent to the substrate. A free-sliding interface is shown to be able to cause “reflection” of oncoming dislocations and enhance film plasticity. A rigidly bonded interface, on the other hand, is seen to initially resist approaching dislocations. Partial tangential sliding at the interface results in a transitional behavior between the two extremes, as revealed in our parametric analysis. The dislocation-interface reaction occurs more sluggishly as the atomic sliding capability decreases. The sliding capability of interface atoms is also seen to dictate the overall deformation and damage initiation in the film.