Strength and fracture behaviour of metal matrix particulate composites.

The fracture strengths of various metal matrix particulate composites prepared by a liquid metallurgy technique were analysed. Data on composites from other investigations in which a powder metallurgy or precipitation technique was employed were also included for comparison. The particulate composites were categorized and micromechanical modelling was carried out with due emphasis on fracture mechanisms. It was found that the strength versus volume fraction relation follows a two-thirds power law in the aluminium-graphite system. In the AlAl2O3 system the classical strengthening theory of short-fibre-reinforced composites was found to hold good. In aluminium-glass and AlSiC systems the experimentally determined strengths are higher than the theoretical estimates, while in aluminium-zircon and dual-phase steels the law of mixtures is obeyed. The important roles played by particle-matrix bonding and microstructure are emphasized with a view to improving the development of composit