"Dislocation-interface" interaction - stress accommodation processes at interfaces

Interactions between lattice dislocations and interfaces occur during plast ic deformation of polycrystals. The resulting stresses in the interfaces mu st be relieved in order that the deformation goes on. This paper deals main ly with these relaxation processes which strongly depend on the interface s tructure and which may occur within the interface itself or in the neighbou ring crystals. The theoretical accommodation models are compared with recen t experimental results obtained by the coupling of four transmission electr on microscopy techniques: conventional, weak beam, in situ and high resolut ion. The relaxation phenomena observed in singular and vicinal interfaces, although more complex than the predicted ones, may be described in terms of incorporation or "direct" transmission implying discrete dislocation produ cts. On the contrary, the accommodation of the interfacial stresses in gene ral interfaces seems to proceed by a delocalization process or by indirect transmission. These two later processes need to be better understood and th e limit between the different interface behaviors need to be emphasized if the final goal is to control the interface contribution to the overall beha vior of the materials. (C) 2001 Elsevier Science B.V. All rights reserved.