Microstructure, mechanical and fracture properties of groundnut shell ash and silicon carbide dispersion strengthened aluminium matrix composites

The mechanical properties of aluminium hybrid composites reinforced with groundnut shell ash (GSA) and silicon carbide was investigated. GSA and silicon carbide with different mix ratios (10:0, 7.5:2.5, 5.0:5.0, 2.5:7.5 and 0:10) constituted 6 and 10 wt.% of the reinforcing phase, while the matrix material was Al-Mg-Si alloy. The hybrid composites were produced via a two-step stir casting technique. Microstructural examination, hardness, tensile and fracture toughness testing were carried out to appraise the mechanical properties of the composites. The results show that with increasing GSA in the reinforcing phase, the hardness, ultimate tensile strength (UTS) and specific strength of the composites decreased slightly for both 6 and 10 wt.% reinforced Al-Mg-Si based composites owing to the amount of the oxides of Al, Si, Ca, K2 and Mg present in the composition of GSA. However, the percentage elongation improved marginally and was generally invariant to increasing GSA content while the fracture toughness increased with increasing GSA content. GSA offered a favourable influence on the mechanical properties of Al-Mg-Si hybrid composites comparable to that of rice husk ash and bamboo leaf ash.