The interactions between 60° dislocation pile-ups with grain boundaries were studied using multi-scale modelling. Careful quantitative analyses of complex processes associated with 60° dislocation absorption and transmission phenomena at Σ3, Σ9 and Σ11 symmetrical tilt boundaries in Al were interpreted in terms of a set of modified Lee–Robertson–Birnbaum criteria. The results and the modified Lee–Robertson–Birnbaum criteria explained experimental observations, rationalized new mechanisms such as deformation twinning and the formation of extended stacking faults, showed that reactions could be controlled more strongly by the leading partial of an incoming dislocation rather than the full Burgers vector and demonstrated that non-Schmid stresses (e.g. shear and compressive stresses along the grain boundary, grain-boundary dislocation processes and step-height changes on the grain boundary) all influenced the critical nucleation stress; but to differing degrees among different tilt boundaries. The modified Lee–Robertson–Birnbaum criteria did not capture the effects of local grain-boundary structure that could also influence behavior. Quantitative metrics based upon the modified Lee–Robertson–Birnbaum criteria were formulated, using the simulation results, for various absorption and transmission phenomena. These metrics could be used as input into mesoscale models such as discrete dislocation plasticity, so that atomic-scale observations could inform higher-scale predictions plasticity.

Multiscale Modeling of Dislocation/Grain-Boundary Interactions: III. 60° Dislocations Impinging on Σ3, Σ9 and Σ11 Tilt Boundaries in Al. M.Dewald, W.A.Curtin: Modelling and Simulation in Materials Science and Engineering, 2011, 19[5], 055002