A composite of a metal matrix with one or more incorporated secondary phases is referred to as a metal matrix composite (MMC). Secondary phase refers to all the particles or fibers which have a different composition than the metal matrix, and which are incorporated therein. As incorporation phases, elements and compounds are possible which, as a result of their material characteristics, are suited for improving individual properties of the metal matrix.Besides an improvement in individual properties of the pure metal matrix as a result of the incorporated secondary phase, certain properties of the metal are also degraded, in particular by particles having a size of 1 to 50 .mu.m. For example, the elongation at break decreases, the strength may decrease, or the tribology may become less favorable. The object of the invention is to improve the properties of the composites by an appropriate selection of the size and type of fibers and/or particles in the secondary phase, and/or the formation of a special pore structure in the preform.