Fabrication and Characterization of Aluminium Metal Matrix Composite Using Ultrasonic-Assisted Stir and Squeeze Casting

Abstract

This study focuses on fabricating and characterising an aluminium metal matrix composite (Al-MMC) reinforced with alumina and fly ash cenosphere, utilising ultrasonic-assisted stir casting followed by squeeze casting. Scrap aluminium alloy wheels were repurposed as the matrix material, providing a sustainable and cost-effective manufacturing method that combines recycled aluminium with lightweight and high-strength reinforcements. The purity and chemical composition of both the matrix and reinforcement materials were confirmed prior to processing using X-ray diffraction (XRD), scanning electron microscopy (SEM), optical microscopy, and X-ray fluorescence (XRF) analysis. The ultrasonic treatment promoted uniform dispersion of the reinforcements, while squeeze casting minimised porosity and enhanced interfacial bonding. The fabricated composites were characterised using optical microscopy, XRD, SEM, density measurements, hardness testing, and porosity assessments to evaluate phase composition, microstructural refinement, and physical and mechanical properties. The results indicate that the developed Al-MMC exhibits reduced porosity, a refined microstructure, improved density stability, and significantly higher hardness than the base aluminium alloy. The incorporation of lightweight cenosphere further decreased the composite's density without compromising strength. These improvements demonstrate the potential of using recycled aluminum, alumina, and cenosphere reinforcements to create high-performance, lightweight, and environmentally sustainable composites suitable for automotive, aerospace, and other engineering applications, where strength-to-weight ratio and sustainability are critical.