Characterization of particle concentration in indentation-deformed metal-ceramic composites

Previous studies have shown that the indentation technique is prone to overestimate the overall strength of heterogeneous materials containing hard particles in a ductile matrix. The localized increase in particle concentration under the indentation has been proposed as a possible cause. In this study, a direct characterization is undertaken using an aluminum/silicon carbide metal matrix composite. Quantitative metallography on the post-indented material is carried out to measure the particle volume fraction. A distinct increase in particle concentration induced by the indentation is found. The spatial distribution of particle concentration is also examined in detail. The residual compressive stress field remained in the material after unloading, as illustrated by the finite element analysis, is shown to correlate with the experimental measurement of the particle concentration. (C) 2004 Elsevier Inc. All rights reserved.