Dislocation dynamics analysis of dislocation intersections in nanoscale metallic multilayered composites

In this work, dislocation dynamics (DD) analysis is used to investigate the strength of nanoscale metallic multilayered composites. Several possible interactions between threading (glide) dislocations and intersecting interfacial dislocations are considered and found to lead to strength predictions in better agreement with experimental trends and significantly higher than the predictions of the simplified confined layer plasticity model based on Orowan bowing of single dislocation in a rigid channel. The strongest interaction occurs when threading and intersecting interfacial dislocations have collinear Burgers' vector and involves an annihilation reaction at their crossing points followed by the resumption of threading with a new dislocation configuration. The other possible dislocation intersections involve the formation of junctions, which are found to be more complex than simple models suggest. When the layer interfaces are modeled as impenetrable walls, as in existing analytical and some dislocation dynamics (DD) models, the predicted strengthening effect is weaker than that predicted by DD with more physical boundary conditions at the interfaces.