Spray Forming of Metal Matrix Composites

Abstract

Spray forming is emerging as a viable technology for the fabrication of discontinuously reinforced metal matrix composites. Advantages of this hybrid powder metallurgy approach reside in near net shape capability, the development of fine scale microstructures devoid of macrosegregation and porosity, and the presence of a uniform distribution of the reinforcing constituents in the matrix. In spray forming, interfacial properties are not compromised and the need to handle fine powder is eliminated. There are two primary adaptations of the Osprey process used in the processing of discontinuously reinforced metal matrix composites, namely reactive (in situ) spray forming, and inert spray forming. The former embraces spray processing with attendant gas–liquid reactions, liquid–liquid reactions, or liquid–solid reactions. In inert spray forming benign particles are injected into the metal spray. These approaches are analysed and their application to diverse metal matrix composites is described. It is demonstrated that reactive spray forming in the Osprey mode provides unique opportunities with respect to the synthesis of new composite systems. PM/0647