Influence of Boron Fiber Powder and Graphite Reinforcements on Physical and Mechanical Properties of Aluminum 2024 Alloy Fabricated by Stir Casting

Abstract

In this study, boron fiber powder and graphite is reinforced to Al 2024 alloy to develop hybrid metal matrix composite by stir casting process. Hybrid MMCs developed with different weight fraction for 4%, 6%, 8% and 10% of boron fiber and 2% of graphite. Stirring parameters are optimized to obtain solid casting. Reinforcements are poured into molten aluminium at 15 g/min and stirrer is rotated for 5 minutes at 250 rpm with two stages stirring. 1% of magnesium was added to improve the wettability of Al 2024. Cast samples are machined as per the standards to investigate the microstructure, physical and mechanical properties. Optical and SEM analysis was carried out on machined sample to study the uniform distribution of particles. XRD and EDAX analysis is carried out to confirm the dispersion of particles into the matrix. Uniform distribution of the particles is found in optical and SEM images for these stirring parameters. The peak representation of boron and graphite particles is also observed in XRD and EDAX analysis. Theoretical and experimental density of the cast sample is determined by rule of mixture and Archimedes principle. Result shows the density of the composite decreases by increasing percentage of reinforcements. Micro Vickers hardness was tested on the cast composites and the result showed Al 2024 alloy hardness was increased by 31.25% by reinforcing boron and graphite. Similarly, tensile and compression strength increased by increasing the percentage of reinforcement. Tensile and compression strength of Al 2024 alloy increased by 45.23% and 29.18% respectively. The ductility of the composites decreased by increasing the percentage of reinforcements.