On particle size effects: An internal length mean field approach using field dislocation mechanics

A mean field approach including an internal length scale is developed in order to capture the particle size effects on the overall mechanical behavior of particle-reinforced alloys. A generalized self-consistent scheme (with coated particles) is employed, with a new “phase” representing the “layers” where orderly dislocations between the matrix and the particles are present. The thickness of these “layers” is the internal length scale introduced in the model. It is determined dynamically by using a one-dimensional field dislocation mechanics model, where localized geometrically necessary dislocation densities accommodate the lattice incompatibility between matrix and inclusions. The beneficial influence of this scheme, as compared to classical mean field approaches, is shown from comparisons with experimental data on the particle size effects in Al/SiC composites.