Investigations of precipitation hardening were performed in term of analysis of distributions of geometrically necessary dislocations surrounding particles. The dislocation microstructures were computed from three dimensional discrete dislocation dynamics and strain gradient plasticity models. Discrete dislocation dynamics simulations of spherical particle embedded in a single crystal matrix undergoing single slip provided the geometrically necessary dislocation structures and the associated work-hardening. A three-dimensional periodic arrangement of particles with cubic symmetry was considered. It was found that a network of slip and kink deformation bands developed, which was strongly dependent upon the crystal lattice orientation of the matrix with respect to the particle array. For some relative orientations, the strain hardening was increased by the distributions of geometrically necessary dislocations which acted as additional barrier against slip. Some of these features were also captured with the strain gradient plasticity model in contrast to conventional continuum crystal plasticity.

Analysis of Particle Induced Dislocation Structures Using Three-Dimensional Dislocation Dynamics and Strain Gradient Plasticity. H.J.Chang, A.Gaubert, M.Fivel, S.Berbenni, O.Bouaziz, S.Forest: Computational Materials Science, 2012, 52[1], 33-9