Influence of fly ash particles on tensile and impact behaviour of aluminium (Al/3Cu/8.5Si) metal matrix composites

The present work aimed to study the tensile and impact behaviour of fly ash particle reinforced aluminium matrix composites. Fly ash particles reinforced aluminium (Al/3Cu/8.5Si) matrix composites were fabricated by the stir casting technique. Three different size ranges of fly ash particles (50–75, 75–103 and 103–150 μm) were used. The composites were subjected to tensile and impact tests. The tensile and impact fracture surfaces of the aluminium alloy and composites were investigated using a scanning electron microscope to characterise the fracture mechanism of the composites. The tensile strength of composites increased, while the ductility and impact strength of composites decreased with an increase in fly ash particle content. The fracture surface of the unreinforced material was characterised by uneven distribution of a large number of dimples resulting in ductile failure. In the case of composites, the presence of hard and brittle reinforcement particles in the ductile aluminium matrix places constraints on the plastic flow of the matrix leading to brittle failure with an increase in fly ash particles.