Dislocation glide in a metal matrix with spherical precipitates was simulated on a computer. The critical resolved shear stress was derived, and the superposition of 2 strengthening effects was investigated. Firstly, the precipitates were incoherent; they could not therefore be sheared but were overcome by the Orowan process (dispersion strengthening). Secondly, the precipitates have a size mismatch and the respective elastic stresses inhibited dislocation glide (size-mismatch strengthening). The simulations were based on the local equilibrium of resolved stresses in one glide plane and the elastic dislocation self-interaction was fully allowed for. The size distribution of the particles and their arrangement in space were very close to those of an actual Ostwald-ripened crystal. The mean particle radius, their volume fraction and the constrained size mismatch parameter were varied in wide ranges. The critical resolved shear stress was presented as a function of these three parameters and an empirical law of superposition was proposed.

Superposition of Dispersion Strengthening and Size-Mismatch Strengthening - Computer Simulations. V.Mohles: Philosophical Magazine Letters, 2003, 83[1], 9-19