“Dislocation–interface” interaction — stress accommodation processes at interfaces

Interactions between lattice dislocations and interfaces occur during plastic deformation of polycrystals. The resulting stresses in the interfaces must be relieved in order that the deformation goes on. This paper deals mainly with these relaxation processes which strongly depend on the interface structure and which may occur within the interface itself or in the neighbouring crystals. The theoretical accommodation models are compared with recent experimental results obtained by the coupling of four transmission electron microscopy techniques: conventional, weak beam, in situ and high resolution. 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 products. On the contrary, the accommodation of the interfacial stresses in general interfaces seems to proceed by a delocalization process or by indirect transmission. These two later processes need to be better understood and the limit between the different interface behaviors need to be emphasized if the final goal is to control the interface contribution to the overall behavior of the materials.