A new model for the evolution of dislocation structure of cell forming metals and alloys through severe plastic deformation was presented. Following previous approaches, the model considers a cellular dislocation structure consisted of two phases: cell interiors and cell walls. The model distinguishes edge and screw dislocations in terms of three categories: mobile dislocations, immobile dislocations in cell interiors and immobile dislocations in cell walls. Then considering physical and geometrical assumptions for each dislocation category, an evolutional law was derived, based upon some dislocation interaction mechanisms such as dislocation generation, annihilation, locking and migration. The model was applied to a severe plastic deformation process of aluminium called constrained groove pressing. The outputs of model were detailed description about dislocation densities (densities of edge and screw dislocations of all three mentioned categories) and cell size evolutions during deformation. To verify the results of modelling, X-ray diffraction patterns of deformed samples were analyzed. The achieved dislocation densities and cell sizes from the X-ray tests were compared with that achieved from the model and a good agreement was obtained.

A New Microstructural Model Based on Dislocation Generation and Consumption Mechanisms Through Severe Plastic Deformation. E.Hosseini, M.Kazeminezhad: Computational Materials Science, 2011, 50[3], 1123-35