Invited Lecture
Climb via vacancy diffusion of edge dislocations in 2D dislocation microstructures

One of the microstructural mechanisms that govern deformation by creep is dislocation motion due to absorption or emission of vacancies. Despite the importance of this mechanism, called dislocation climb, it is assumed by most climb models in literature that the dislocation network is homogeneous and dilute, which allow treating each dislocation as isolated sink (or source) for vacancies. This assumption of isolated independent sinks is far from being true in many cases, such as in dislocation dipoles, dislocation pile ups, dislocation walls. In these cases, one expects for the diffusion field of the vacancies to be coordinated with the dislocations network, which in turn determines how the climb rate of each dislocation is affected from the whole network. In this talk we present a climb model that accounts for the collective effect of the dislocation network, by solving the diffusion equation for vacancies in a region with a general two dimensional dislocation distribution. The definition of the sink strength is extended, to account for the contributions of neighboring dislocations to the climb rate. The model is then applied to dislocation dipoles and dislocation pile-ups, which are dense dislocation structures, and we discuss how the dislocation sink strength of dislocations is altered. In particular, this coordinated climb motion of neighboring dislocations is important to the disassembly of dislocation pile-ups. Based upon the conclusions of this work, we discuss the importance of our results to modelling deformation creep.