Synthesis and characterization of A319 and A380 Al–Si alloy matrix composites reinforced with Y2O3 and TiO2 nanoparticles using machining chips as feedstock

This work investigates the production of Y2O3- and TiO2-reinforced A319 and A380 Al-Si matrix composites from aluminum machining chips through high-energy mechanical milling, uniaxial pressing, and sintering. XRD confirmed the presence of α-Al, eutectic Si, and the reinforcing oxides without detectable reaction products, while SEM–EDS and image analysis demonstrated effective reinforcement incorporation and retention, metallic-particle refinement, and reduced porosity. Reinforcement increased Vickers microhardness by 39.3–50.4% relative to the corresponding unreinforced alloys. The highest hardness was achieved in the A380-Y2O3 composite, which also exhibited the smallest metallic particle size and one of the lowest porosity levels. The superior hardening response of the Y2O3-reinforced composites is attributed to reinforcement dispersion, particle refinement, improved densification, and possible microstructural stabilization associated with the high thermal stability of Y2O3. Overall, the results demonstrate an effective solid-state route for transforming machining chips into Al-Si matrix composites with enhanced microstructural and mechanical properties.