Dynamic simulations of the interaction between dislocations and dilute particle concentrations in metal-matrix composites (MMCs)

3D Dislocation Dynamics (DD) simulations are presented which capture the interaction between gliding dislocations in a ductile metallic matrix and nearby dispersed spherical particles. Here the strengthening effect arises from the stress field caused by the particle-matrix mismatch, and no image stress caused by the particles is considered. A radial misfit strain of 1%, simulating thermal processing induced elastic field in aluminum matrix-silicon carbide particulate composite system, is used. Attention is limited to composites with reinforcement concentrations smaller than about 3.5% and with particle sizes smaller than about 0.8 mum. The simulations show dislocation storage in the matrix, in the form a pileup of glide loops near the particle and as part of stress relief, which in turn exerts a back stress on upcoming gliding dislocations. This manifests itself in the simulations in increased flow stress as demonstrated by the stress-strain curve. The results show increased flow stress with increased particle volume fraction as would be expected. However, flow stress is also sensitive to other microstructural features such as particle radius and the distance between the dislocations and particles, and to a lesser extent to the spatial arrangement between dislocations and particles. Overall, the calculated strengthening effect is comparable with that found in experiments. (C) 2003 Elsevier Ltd. All rights reserved.