Interface-Engineered Circular AA6061/Fly Ash Composites Fabricated by Semi-Solid Compocasting for Enhanced Mechanical and Environmental Performance

This study develops high-performance AA6061 aluminum composites reinforced with fly ash (FA) via semi-solid compocasting. The process enhances mechanical properties, achieving a 65% increase in microhardness and 41% improvement in tensile strength at 10 wt.% FA, while maintaining 8.1% elongation, surpassing typical SiC-reinforced composites. Interface-controlled microstructural refinement reduces porosity and defects, improving particle-matrix bonding. A life-cycle assessment demonstrates a 0.8–1.0 kg CO2-eq/kg reduction in embodied emissions and more than 95% cost savings through waste valorization. This dual-circularity approach aligns with SDGs 9, 12, and 13, highlighting the sustainability and potential of FA-reinforced AA6061 composites for infrastructure applications.