A method for forming a metal matrix composite body by an outside-in spontaneous infiltration process

The present invention relates to a novel method for forming a metal matrix composite body, and products produced thereby. Particularly, a permeable mass of filler material is formed into a preform (22) the preform (22) having at least a portion thereof which contains a cavity (30). An infiltration enhancer and/or an infiltration enhancer precursor and/or an infiltrating atmosphere are also in communication with the preform (22) at least at some point during the process, which permits molten matrix metal (20) to spontaneously infiltrate the preform (22) when the preform (22) is placed into molten matrix metal (20). An infiltrating atmosphere is provided in communication in the cavity (30) in the preform (22) for at least a portion of the process and molten matrix metal (20) is contacted with an exterior portion of the preform (22) such that molten matrix metal (20) will spontaneously infiltrate the preform (22) from an exterior surface thereof toward the cavity (30).