Effect of stainless steel 309 particulate reinforcement on the microstructure, porosity, hardness, and tribological properties of Al 6061-based composites

This study investigates characterization of Al6061-stainless steel 309 (SS) composites fabricated via powder metallurgy. The research focuses on optimizing the reinforcement volume percentage and milling duration to achieve superior microstructure, hardness, and tribological properties. Initially, Al6061 aluminum powder and an Al6061-5%SS powder mixture were milled for varying durations. Laser particle size analysis (LPSA) and scanning electron microscopy (SEM) identified 90 min as the optimal milling time. Subsequently, composite samples with 5, 8, 10, and 12 vol. % SS particles were prepared using cold pressing and sintering techniques. Characterization involved SEM, optical microscopy (OM), hardness testing, density measurement, and wear analysis. The results revealed an 18% increase in macrohardness for the Al6061-10%SS composite compared to the reference sample (composed of milled aluminum powders), with hardness declining at higher SS contents. Wear testing demonstrated significant improvements in wear resistance and friction behavior with the addition of SS particles. The Al6061-10%SS composite exhibited the best wear performance, with a 91% reduction in wear rate and a 64% decrease in the coefficient of friction compared to the reference sample.