Effect of overaging and particle size on tensile deformation and fracture of particle-reinforced aluminum matrix composites

Abstract

The effect of reinforcement particle size and overaging treatment on the tensile behavior and fracture morphology of a 2080/SiC/20p composite was investigated. Tensile behavior was profoundly influenced by particle size and matrix strength. The composite strength increased with a decrease in particle size, while overaging greatly reduced the strength of the composite, independent of particle size. Almost all particles on the fracture plane were fractured, and the amount of particle fracture in the composites was insensitive to overaging and particle size, due to the excellent bonding between SiC particles and the Al matrix. Fractography showed that void nucleation in the matrix of peak-aged composites took place primarily at very fine SiC particles, which were much smaller than the average SiC particle size. Subsequent failure took place by the tearing topography surface (TTS) mechanism. In the overaged composite, composites failed by a more conventional void nucleation and growth process, where void nucleation took place at coarsened S precipitate particles, resulting in smaller and more elongated voids.