In-situ Synthesis of Al-based Composites Reinforced with TiB2-TiC-Al2O3 Ceramic Particulates

Metal matrix composites (MMCs) reinforced with ceramic particulates have been attractive as high specific strength materials utilized in automobile and aerospace industries. In order to enhance refinement and dispersibility of the ceramic particulates, the synthesis process with in-situ reactions has been investigated. The in-situ synthesis can avoid complex and harmful processes of powder handling and produce fine inclusions in the matrix with rather lower costs than conventional fabrication methods. In this study, the Al-based composites with TiC, TiB 2 and Al 2 O 3 particulates have been prepared by the in-situ reaction synthesis from starting powders of Al, TiO 2 and B 4 C. It was found that the reactions has completed at 1200 ˚C and the temperature could be reduced when finer powder was used as the starting material. The obtained porous sintered samples were subjected to subsequent extrusion processing. The extrudates containing ceramic reinforcements up to 20vol% exhibited high density and homogeneous microstructures with fine ceramic particulates. The mechanical properties such as tensile strength were remarkably improved when the ceramic particulates were induced by in-situ reactions, as a result of enhanced dispersion strengthening.