Modeling planar dislocation boundaries using multi-scale dislocation dynamics plasticity

Results pertaining to the formation and dynamics of planar dislocation boundaries in deformed fcc single crystals using a multi-scale analysis are presented. A pure tilt boundary and experimentally observed extended geometrically necessary boundaries (GNBs) are constructed within the representative volume element (RVE) for multi-scale simulations. The model couples discrete dislocation dynamics analysis with continuum finite element to correct for the boundary conditions and image stress. It is shown that the right boundary condition of the RVE is critical in modeling GNBs and their long-range stresses. Effects of various numerical factors such as domain length and mesh sensitivity are also discussed. The effect of changing the spacing between two dislocation boundaries on the self-stress field and the stability, particularly in the space between the two dislocation boundaries, is presented. Relaxed configurations using dislocation dynamics show formation of a uniform network stabilized by formation of junctions and dipoles.