Microstructural Characterization and Mechanical Performance of Friction Stir Processed Aluminum Matrix Composites

Abstract

Aluminum Matrix Composites (AMCs) have emerged as one of the most promising lightweight structural materials for aerospace, automotive, marine, defense, railway, and highperformance engineering applications owing to their exceptional combination of low density, high specific strength, superior wear resistance, enhanced thermal conductivity, and excellent corrosion resistance. The incorporation of ceramic reinforcements such as silicon carbide (SiC), aluminum oxide (Al₂O₃), boron carbide (B₄C), titanium carbide (TiC), and graphene into aluminum matrices significantly improves hardness, stiffness, fatigue resistance, and high-temperature mechanical properties. However, conventional casting and powder metallurgy techniques often produce reinforcement agglomeration, porosity, poor particle distribution, and weak interfacial bonding, resulting in non-uniform microstructures and reduced mechanical performance. These limitations restrict the full utilization of aluminum matrix composites in demanding structural applications requiring consistent mechanical reliability and long service life. The present study investigates the Microstructural Characterization and Mechanical Performance of Friction Stir Processed Aluminum Matrix Composites using an integrated experimental methodology. Aluminum alloy AA6061 reinforced with silicon carbide particles is processed under various tool rotational speeds, traverse speeds, and processing passes to evaluate the influence of FSP parameters on grain refinement, reinforcement distribution, hardness, tensile strength, impact toughness, and wear resistance. Advanced characterization techniques including Optical Microscopy (OM), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), Electron Backscatter Diffraction (EBSD), and X-ray Diffraction (XRD) are employed to investigate grain evolution, particle dispersion, crystallographic texture, and phase stability. Mechanical evaluation is performed through Vickers microhardness testing, tensile testing, impact testing, and dry sliding wear experiments. The results demonstrate that optimized Friction Stir Processing significantly refines the aluminum matrix microstructure, uniformly disperses ceramic reinforcements, enhances interfacial bonding, and substantially improves mechanical performance compared with the as-cast composite. The findings provide valuable guidance for manufacturing high-performance aluminum matrix composites suitable for advanced lightweight engineering applications.