Thermal, Hardness and Microstructural Characterization of Al-Si-SiC<sub>p</sub> Composites

Abstract

This study investigated the effects of silicon and silicon carbide particles contents on the thermal, hardness and microstructural behaviour of Al-Si-SiCp composites. 16 samples of the composite produced by stir casting technique were of silicon contents of 1, 2, 3 and 4% by weigh, and silicon carbide contents of 0.5, 1, 1.5 and 2% by weight for each composition of silicon. Each of the samples were subjected to homogenizing annealing heat treatment. Differential thermal analysis (DTA), hardness test and microstructural analysis were then performed on the samples from each composition. The results obtained showed that the hardness of the composite increased gradually as the silicon and silicon carbide particles content increased. The micrographs obtained revealed the presence of silicon carbide, silicon precipitates and aluminium carbide (Al4C3) within the metallic matrix. The amounts of these phases varied with the silicon and silicon carbide content. All the samples gave DTA curves with major endothermic peaks between 550 – 570℃ and two sets of exothermic peaks between 580 – 610℃ for the first set and between 565 – 570℃ for the second set. It was inferred from the study that although varied silicon and silicon carbide contents affected the thermal, hardness and microstructural behaviour of the Al-Si-SiCp composites, the variation of the SiCp content had a more pronounced effect on the hardness value of the Al-Si-SiCp composite.