Mechanical and microstructure evaluation of stir cast Al-4.5%Cu alloy reinforced fly ash/boron carbide hybrid metal matrix composites

Abstract

Metal matrix composites (MMCs) have risen to prominence as a structural material in the aerospace and automotive industries. When compared to traditional materials, MMCs have higher specific strength, wear resistance, reduced part weight, less thermal shock, and strength conservation at high temperatures. In this study, it was established that components should be cast using Aluminium Copper as the base matrix, with fly ash and B4C as reinforcement. A composite of 3 wt% and 5 wt% fly ash with 2, 4, and 6 wt% B4C was reinforced in an Al-4.5 wt% Cu matrix for three different diameters of 25, 50, and 75 mm casting. Stir cast composites were tested for hardness, tensile, compression, and impact strength. The results showed that stir casting composites with a 25 mm diameter had better mechanical qualities than those with a 50 mm or 75 mm diameter. For a 25 mm diameter stir casting, the increase in percentage of reinforcements enhanced 20% hardness, 29% tensile strength, 30% compression, and 38%impact strength. Microstructure analysis reveals better bonding between matrix and reinforcement for 25 mm diameter casting compared to 50 and 75 mm castings.