It was demonstrated that dislocation motion in a material with a high dislocation mobility was characterized by large velocity fluctuations which led to intrinsically intermittent dynamics at the microscopic and mesoscopic scales; even if the macroscopic deformation was stable and homogeneous. The large fluctuations indicated that the dislocation system in a deforming crystal was close to a critical point (yielding transition). In the case of the motion of isolated dislocations through weak obstacle fields, this critical point corresponded to the de-pinning transition of an elastic manifold. A phenomenological approach was presented for the modelling of the influence of collective intermittent dislocation motions upon dislocation microstructure evolution. Its applications included the study of the development of misorientations in dislocation cell structures, and the interplay of strain-hardening and dislocation patterning under deformation conditions where fractal dislocation arrangements were formed.

Statistical Modelling of Dislocation Systems. M.Zaiser: Materials Science and Engineering A, 2001, 309-310, 304-15