Homogenization of metal matrix composites by high-pressure torsion

This article deals with the homogenization of metal matrix composites (MMCs) with inhomogeneous particle distribution by severe plastic deformation. In this study, A16061-10 pct SiC and Al6061-20 pct Al^sub 2^O^sub 3^ powder metallurgy (PM) MMCs with clustered particle distribution in the as-fabricated condition are subjected to high-pressure torsion (HPT) at room temperature. The evolution of the microstructure during HPT is investigated. It is shown that, in the two materials, two different types of particle clusters appear that behave differently during deformation. In MMCs with dense particle clusters, the process of declustering during HPT occurs through a mechanism of particle debonding from the surface of the clusters. On the contrary, in MMCs with diffuse particle clusters, the deformation of the clusters is mainly responsible for the homogenization; therefore, the strain necessary to obtain a homogeneous particle distribution can be predicted by the Tan and Zhang model (M.J. Tan and X. Zhang: Mater. Sci. Eng. A, 1998, vol. 244, pp. 80-85). [PUBLICATION ABSTRACT]