Influence of Fly Ash on Microstructure and Mechanical Properties of Aluminium (Al/7Si) Alloy Composite

Metal matrix composites (MMC) have a wide range of applications in today's world, due to their high strength to weight ratio. In the present work, aluminium alloy LM25 and fly ash are selected as matrix and reinforced materials, respectively. Fly ash is a waste product in thermal power plants. Its ease availability in low cost can be converted into useful product. MMC of aluminium alloy LM25-with 5 and 7.5% wt. fly ash composite is made by stir casting. The composite mechanical properties are compared with aluminium alloy. The chemical composition of aluminium alloy and its composite are studied by optical emission spectroscopy. The mechanical properties such as tensile strength, elongation and hardness are obtained by employing UTM and Brinell hardness tester. The specimens' microstructure and phase analysis are studied using an optical microscope and XRD. A segregation of fly ash is found in the grain boundaries in the microstructure. The mechanical properties show significant enhancement from the base metal. The various defects present in the casting are studied with the help of radiography technique.