Equal channel angular pressing of metal matrix composites: Effect on particle distribution and fracture toughness

An A16061-20%Al2O3 powder metallurgy (PM) metal matrix composite (MMC) with a strongly clustered particle distribution is subjected to equal channel angular pressing (ECAP) at a temperature of 370 degrees C. The evolution of the homogeneity of the particle distribution in the material during ECAP is investigated by the quadrat method. The model proposed by Tan and Zhang [Mater Sci Eng 1998;244:80] for estimating the critical particle size which is required for a homogeneous particle distribution in PM MMCs is extended to the case of a combination of extrusion and ECAP. The applicability of the model to predict a homogeneity of the particle distribution after extrusion and ECAP is discussed. It is shown that ECAP leads to an increase of the uniformity of the particle distribution and the fracture toughness. (c) 2005 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.