Self-supporting bodies are produced by reactive infiltration of a parent metal into boron carbide typically resulting in a composite comprising a boron-containing compound and metal. The mass to be infiltrated may contain one or more inert fillers admixed with the boron carbide, or at least one carbon donor material, to produce a composite by reactive infiltration, which composite comprises a matrix of metal and boron-containing compound embedding the filler. In one embodiment of the invention, a parent metal is reactively infiltrated into a mass comprising a boron carbide material mixed with a carbon-containing compound. In this embodiment, a self-supporting composite is formed typically comprising a boron-containing compound, a carbon-containing compound, and metal. The relative amounts of reactants and process conditions may be altered or controlled to yield a body containing varying volume percents of ceramic, metal and/or porosity. The mass to be infiltrated can be contained within a refractory vessel having a venting means included therein.