Interpretation of plastic deformation by means of dislocation-disclination reaction kinetics

The microstructure development under plastic deformation up to large strains is modelled by means of four-component reaction kinetics for the densities of mobile and immobile dislocations and disclinations. The resulting system of nonlinear differential equations is able to describe the transition from a dislocation-dominated to a disclination-controlled kinetics running into a (quasi-)stationary state, and finally, into an instability. For an estimation of the resulting flow stress three contributions are taken into account: a redundant dislocation contribution governed by a Taylor law, a subgrain size contribution governed by a Hall-Fetch relationship, and a misorientation contribution. To connect the density of sessile disclinations to the mean subgrain size and the mean misorientation, new relationships based on stochastic geometry are used. (C) 1997 Elsevier Science S.A.