A numerical model was developed for simulating yielding in composites, which treated the transmission of slip across a dissimilar interface via the formation of co-planar dislocation arrays in both phases. A pile-up of dislocations in the soft phase was assumed to nucleate dislocations in the hard phase, where movement was dictated by the lattice friction stress. The polycrystalline-composite yield stress was calculated by determining the equilibrium positions of the dislocation arrays as a function of the length scales, elastic constants and Burgers vectors in the 2 phases. This had particular relevance to melt-oxidized Al/Al2O3, where homophase boundaries were absent, and to the Co/WC system. The hardness values which were predicted by this model were in good agreement with experimentally measured values in the latter systems.

A Dislocation Pile-Up Model for the Yield Stress of a Composite. V.Jayaram, N.N.Viswanathan, T.A.Abinandanan: Acta Materialia, 1999, 47[5], 1635-43