Low strain plasticity in a particulate metal matrix composite

The strengthening that arises when reinforcing an aluminum alloy with approximately equiaxed shaped SiC particles has been measured, with careful attention paid to the elastic-plastic transition. The results indicate that the majority of strengthening develops at low strains, due to the high initial strain hardening rate exhibited by these composite materials. This can be interpreted in terms of stress partitioning to the second phase particles during the elastic/plastic transition and beyond. The experimental results are compared with a self-consistent model based on Eshelby's equivalent inclusion method. The model predictions are in good agreement with experimental data, once effects due to the inhomogeneous distribution of particles are incorporated.