Solid-State Joining of Metal Matrix Composites: A Survey of Challenges and Potential Solutions

This article examines the challenges associated with joining particulate-reinforced metal matrix composites (MMCs). A survey of published research reveals the problems inherent in fusion welding of MMCs, namely, porosity and the formation of a deleterious theta phase precipitated by the reaction of molten Aluminum with the reinforcement. The theta phase is absent in joints produced using friction stir welding (FSW), a solid-state process. FSW, however, is not a panacea, as FSW welds of MMCs are characterized by rapid and severe wear of the welding tool. Research efforts to characterize and mitigate wear incurred during this process are also documented.