Abstract: A cast composite material is formed from about 5 to about 35 volume percent of particulate reinforcement, preferably silicon carbide particles, embedded in an aluminum alloy matrix having from about 8.5 to about 12.6, most preferably about 9.5 to about 11.0, weight percent silicon. The cast composite material is particularly well suited for use as a foundry alloy for remelting purposes. Other alloying elements may be added without interfering with the beneficial effects of the silicon.

Abstract: A metal matrix composite material containing discontinuous particles in a metallic matrix is prepared by forming a mixture of the molten alloy and the particles in a closed reactor, removing oxygen from the interior of the reactor, statically pressurizing the interior of the reactor with nitrogen gas, mixing the mixture of the molten alloy and particles in the presence of the static nitrogen gas to wet the molten matrix to the particles, and evacuating the interior of the reactor in a stepwise manner. The nitrogen gas aids in wetting the metallic alloy to the particles by forming aluminum nitride at the particle-molten matrix interface, so that a lower contact angle of the alloy to the particle results. Oxygen that may be present in the sealed reactor is gettered by the aluminum, and the nitrogen is removed by stepwise evacuation, thereby minimizing the introduction of gas into, and retention of gas within, the melt.