Effect of particle size ratio and particle clustering on sintering and stiffness of aluminium matrix composite.

A metal matrix composite with a matrix composition of Al–3·8Cu–1Mg–0·75Si–0·5Sn was fabricated by sintering a particulate ceramic reinforcement with elemental metal powders. The sintering characteristics were examined as a function of reinforcement volume fraction, particle size and particle size ratio. At high volume fractions of reinforcement, densification ceased completely and the compacts expanded during sintering. Coarse reinforcement particles, not large particle size ratios, maximised the sintering response. Clustering of the ceramic was studied using Dirichelet tessellations of sintered microstructures. While clustering is evident in the sintered microstructures, it does not correlate to sintered density through the particle size ratio because the ceramic particles appear to rearrange in the presence of a large volume of sintering liquid. The effect of particle size is not due to clustering but maybe due to ceramic particle surface area. [ABSTRACT FROM AUTHOR]