Modeling of dislocation–grain boundary interactions in FCC metals

In this paper recent 2D and 3D computational modeling studies of the interaction between dislocations and grain boundaries (GB) in FCC metals will be presented. 2D simulations of lattice dislocation interaction with Σ11 tilt GBs in Al are presented and discussed. Studies of a Σ11 symmetric tilt GB reveal that transmitted dislocations result in local GB migration and disconnection formation. A classical elastic analysis makes correct predictions in one case but not another. Glissile GB dislocations are created in this process, which means that part of the transmitted dislocation is absorbed. Calculations of lattice dislocations interacting with a Σ11 asymmetric tilt GB show that the nature of the interaction depends on local GB structure and transmission is observed in some cases to occur on planes that do not have the highest resolved glide stress. Results of large-scale 3D molecular dynamic simulations are also described, investigating the interaction between dislocations nucleating from a crack tip and a number of symmetric tilt GBs in Ni. Using a line-tension model to analyze the data, it is found that the outcomes of dislocation–GB collisions can be rationalized in terms of only three geometrical parameters, in accordance with in situ TEM observations.