A new casting process for fabrication of particle-reinforced metals is presented whereby a composite of particulate reinforcing phase in metal is first produced by pressure infiltration. This composite is then diluted in additional molten metal to obtain the desired reinforcement volume fraction and metal composition. This process produces a pore-free as-cast particulate metal-matrix composite. This process is demonstrated for fabrication of magnesium-matrix composites containing SiC reinforcements of average diameter 30, 10 and 3-mu-m. It is compared with the compocasting process, which was investigated as well for similar SiC particles in Mg-10 wt % Al, and resulted in unacceptable levels of porosity in the as-cast composite.