Characterization of Indentation-induced ‘Particle Crowding’ in Metal Matrix Composites

Abstract

A direct experimental characterization of reinforcement configuration in an indentation-deformed metal matrix composite is undertaken. The primary objective is to quantify the possible local increase in particle concentration, which has been proposed to cause inconsistency in the indentation hardness and the overall composite strength. Quantitative metallography on the post-indented material is carried out to measure the particle volume fraction. Multiple cross sections of an indentation are investigated with the statistically significant results obtained. 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 upon unloading, as illustrated by the finite element analysis, is shown to be in qualitative agreement with the measurement.