Dislocation patterning:: The role of climb in meso-scale simulations

Simulation of parallel dynamics of edge dislocations in a 2D hexagonal lattice is carried out on a large scale by means of coarse graining, in the absence of external strain. In order to study the effect of climb on dislocation pattern formation, we allowed (i) isotropic (ii) biased (iii) only glide mobility. Moreover we annihilated dislocations with opposite Burgers vectors close to each other. The main result is that in cases (i) and (ii) cellular structure emerges, for (ii) this happens after a longer transient, while (iii) gives a diffuse looking pattern, similar to former single slip plane simulations. In the course of the evolution of dislocation number and cell size they statistically well satisfy Holt's relation. The cell structure found appears to have a characteristic cell size, in contrast to fractal examples in the presence of mechanical strain. Despite the simplicity of our model, the results are consistent with the recently detected low-density dislocation patterns in melt-grown, non-post-deformed crystals. (c) 2006 Elsevier B.V. All rights reserved.