Abstract: This paper deals with the microstructure-property relationship in metal-ceramic particulate reinforced composites. Metal matrix was 7075 aluminum alloy and was reinforced with 20% by volume of either F-600 grade or F-1000 grade SiC particulates. Through tensile ductility and fracture toughness, and by means of frac-tography of TEM and SEM, the details of the fracture were investigated. The result showed that fracture tended to initiate in clustered regions. A tendency to shift the fracture mode from particle cracking to dimpled fracture was observed as the matrix temper was varied from underaged to overaged. While TEM revealed a new phase of precipitation at the particle/matrix interface in the overaged and it accompanied a substantial decrease in toughness.