Abstract: A ternary metal matrix composite comprising a metallic binding matrix material and a reinforcement material consisting essentially of an insoluble ceramic and a semi-metal. The ternary metal matrix composite of the invention has a coefficient of thermal expansion which is lower and more consistent than that of known binary composites using similar materials. The coefficient of thermal expansion may be tailored to meet specific application needs. The invention also has a low density, good thermal conductivity, dimensional stability, and formability. In one form of the invention, the insoluble ceramic and semi-metal contain the same element. In a preferred form of the invention, the ternary metal matrix composite comprises an aluminum alloy matrix and a reinforcement material of silicon carbide and silicon.