Plastic Behavior of Aluminum and Dislocation Patterning Based on Continuum Dislocation Dynamic (CDD)

In this study, a continuum multiscale model based on discrete dislocation dynamics and viscoplastic self-consistent theory is developed. The model is capable of describing the macroscopic deformation behavior of polycrystalline metals and alloys, maintaining at the same time a microscopic level resolution that captures the dislocation density patterns within each grain. The continuum dislocation dynamics model is based on a set of nonlinear partial differential equations of the dislocation densities inside each grain. Three different types of dislocations, two mobile (positive and negative) and one immobile, are considered. The shear strain within each grain is calculated by the total dislocation density at every time step, and then linked to the viscoplastic self-consistent framework to calculate the macroscopic behavior of the polycrystalline material. At the same time, the dislocation density pattering within each grain, calculated by the evolution equations, is recorded to provide a local view of the material at grain level. For the purpose of demonstration, the focus of this paper is on polycrystalline Aluminum and the numerical solutions are compared with experimental data.