Microstructural and mechanical characteristics of in situ metal matrix composites

During the past decade, considerable research effort has been directed towa rds the development of in situ metal matrix composites (MMCs), in which the reinforcements are formed in situ by exothermal reactions between elements or between elements and compounds. Using this approach, MMCs with a wide r ange of matrix materials (including aluminum, titanium, copper, nickel and iron), and second-phase particles (including borides, carbides, nitrides, o xides and their mixtures) have been produced. Because of the formation of u ltrafine and stable ceramic reinforcements, the in situ MMCs are found to e xhibit excellent mechanical properties. In this review article, current dev elopment on the fabrication, microstructure and mechanical properties of th e composites reinforced with in situ ceramic phases will be addressed. Part icular attention is paid to the mechanisms responsible for the formation of in situ reinforcements, and for creep failure of the aluminum-based matrix composites. (C) 2000 Elsevier Science S.A. All rights reserved.