Effect of extrusion temperature on the microstructure and porosity of A356-SiCp composites

The effect of extrusion temperature on the microstructure and porosity of Al A356-10 vol.% SiC composites was investigated. Composites containing three different particle sizes of 38, 62 and 82 μm fabricated by compocasting (SL) method were extruded at three different temperatures of 450, 500, and 550 °C using an extrusion ratio of 18:1. The extruded composites exhibited reduced porosity as well as a more uniform particle distribution when compared with the as-cast samples. Image analysis showed that the SiC particles were refined by the extrusion process and that the extent of the refinement decreased with the extrusion temperature. These results indicate the extrusion-induced particle fracture when particle-reinforced metal matrix composites (MMCs) are extruded at a relatively low temperature.