Particle distribution in cast metal matrix composites—Part I

The widespread adoption of particulate metal matrix composites (MMCs) for engineering applications has been hindered by the high cost of producing components of even minimally complex shape. Casting technology may be the key to overcoming this problem, although several technical challenges currently exist with this method. Achieving a uniform distribution of reinforcement within the matrix is one such challenge which impacts directly on the properties and quality of the composite material. In the case of particle reinforced metal matrix composites, the distribution of the reinforcement particles in the matrix alloy is influenced by several factors during casting. These include the rheological behaviour of the matrix melt, the particle incorporation method, interactions of the particles and the matrix before, during and after mixing, and the changing particle distribution during solidification. The large differences in bulk properties (e.g. density) between particles and matrix materials play a significant role, as do the surface properties of the reinforcement powders. In this paper, research relevant to these factors which influence particles distribution is reviewed and discussed.