Abstract: The microstructure of a metal matrix composite comprising copper and reinforcement material is improved when the metal matrix composite comprises at least about 0.02% by weight of at least one of silver and gold. In one embodiment, the process for making a metal matrix composite comprises compacting powder particles of a reinforcement material to form a green compact, sintering the green compact to produce a porous skeletal body and infiltrating the porous skeletal body with an infiltrant comprising copper and at least about 0.1% of at least one of silver and gold, based on the weight of infiltrant. In another embodiment, the process comprises forming a mixture of particles of reinforcement material, copper and at least about 0.02% by weight of at least one of silver and gold, compacting the mixture to form a green compact, and sintering the green compact to form a near net shape metal matrix composite.

Abstract: The thermal conductivity, thermal conductivity, of a sintered copper/refractory metal composite having a maximum porosity of about 1% is greatly improved when the composite contains phosphorus and sintering aid in a specified weight ratio, “phosphorus/sintering aid ratio.” The copper/refractory matrix composite herein comprises, by weight, from about 5% to about 30% copper, from about 0.2% to about 0.6% sintering aid, from about 0.08% to about 0.3% phosphorus, the remaining metal is refractory metal. The phosphorus to sintering aid ratio ranges from about 0.25 to about 0.55. In one embodiment of the invention the sintering aid contains cobalt and the refractory metal is tungsten.