Self-organization model of localization of cyclic strain into PSBs and formation of dislocation wall structure

Development of dislocation structures in cubic metal crystals cyclically de formed in single slip is treated as a self-organization process. The propos ed model consists of the crystal plasticity equations, the equation of moti on of glide dislocations, and the balance equation for stored dislocations (dipolar loops). The model incorporates hardening by the loops, sweeping of the loops by glide dislocations, drift of the loops in the stress gradient s, the mutual loop interaction, their generation and annihilation. By using analytical methods it is briefly shown that in the early stage of deformat ion the vein or extended wall structure is formed. In the saturation state when all newly formed dislocations are annihilated strain becomes localized . In the lamellae of concentrated slip (PSBs) the dislocation structure may be but need not to be rearranged. The criterion for rearrangement is speci fied. The transformation of veins to walls is a typical rearrangement in PS Bs. (C) 2001 Elsevier Science B.V. All rights reserved.