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Chapter 57 Collective behaviour of dislocations in plasticity

2002; Elsevier BV; Linguagem: Inglês

10.1016/s1572-4859(02)80008-0

2542-7156

L.P. Kubin, C. Fressengeas, G. Ananthakrishna,

Advanced materials and composites

This chapter discusses the collective dislocation behavior in cyclic deformation. During plastic flow, the spatial arrangement of the dislocation structure essentially derives from a competition between two factors. When it exists, the interaction of dislocations with strong and dense localized obstacles other than dislocations (small clusters and precipitates, lattice friction and Peierls forces) tends to induce rather uniform dislocation distributions. In such conditions, the plastic flow properties of the bulk material may simply reflect the behavior of isolated mobile dislocations. In contrast, the mutual interactions of dislocations, both local and long ranged, become all the more important as dislocations multiply. Thus, the contribution of dislocation interactions to the flow stress increases during plastic flow. At a certain stage that is characterized by a critical stress, strain, or dislocation density, the collective dislocation behavior sets in which is characterized by the emergence of dislocation-rich and dislocation-poor regions. This is usually referred to as dislocation patterning.