Microstructure and Mechanical Characteristics of CDA–B4C Hybrid Metal Matrix Composites

Abstract

This study focuses on fabricating aluminium hybrid metal matrix with eco-friendly agro waste, cow dung ash and boron carbide by two stage stir casting. Weight percentage of cow dung ash and boron carbide were reinforced in ratios of 2.5:7.5, 5:5, and 7.5:2.5. The fabricated samples were subjected to optical microscope, scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX) to identify micro structural analysis and phase identification of the reinforcements respectively. The effects on mechanical properties like density, hardness, tensile strength, impact strength and flexural strength properties were studied, and the results are compared to the base alloy (Al 7075). Fracture mechanisms for tensile and impact specimens were analysed through SEM and EDX. Micro structural and SEM images reveal uniform distribution of particles in the matrix. Increasing CDA particles has reduced the density of the hybrid composite up to 8%. A maximum increase in hardness and tensile strength was up to 30% and 56% respectively, and then a slight decrease was found in increasing the CDA particles. The flexural strength has increased to a maximum of 12% at 7.5% CDA and decrement in impact strength was inferred in all the hybrid composites when compared with base alloy. Dimples, transgranular cleavage facets and cracks are revealed from the fractured specimens of tensile and impact specimens.