Particle reinforced metals of high ceramic content

It is commonly considered that, in ceramic particle reinforced metals, the volume fraction of ceramic should not exceed 30% if the composite is intended for structural applications: otherwise its toughness and ductility generally become unacceptably low. Particle reinforced metal matrix composites produced by infiltration provide a material with which this assumption can be tested. We first present a summary of recent results from our laboratory showing that aluminium matrix composites containing 50% or more ceramic particles can be tough, strong and relatively ductile, despite the high ceramic loadings. We then discuss toughening mechanisms that can explain the mechanical properties displayed by these composites, to highlight the importance of the particle strength distribution on the composite fracture toughness.