A Study on the Wear Performance of Friction Stir Processed Al5083/Al ₂ O ₃ and Al5083/Al ₂ O

ABSTRACT

This study investigates the microstructural, mechanical, and tribological properties of friction stir processed (FSPed) Al5083 and Al5083‐based surface composites reinforced with different fractions of Al ₂ O ₃ and Al ₂ O ₃  + h‐BN. Two‐pass, same‐direction FSP was performed at a tool rotation speed of 1250 rpm, a traverse speed of 55 mm/min, an axial force of 5.89 kN, and a tool tilt angle of 3°. The microstructure and phase composition were characterized using SEM, EDS, and XRD, while microhardness and ball‐on‐disk wear tests were conducted to evaluate the mechanical and tribological performance. The reinforcement phases were distributed within the processed composite layers, and XRD confirmed the retention of Al ₂ O ₃ and h‐BN after processing. Williamson–Hall analysis revealed reinforcement‐dependent variations in the apparent crystallite‐domain size and lattice microstrain of the Al matrix. The Al5083/Al ₂ O ₃ composite exhibited the highest hardness, increasing from 89 ± 1.02 HV _0.025 for unreinforced FSPed Al5083 to 132 ± 0.87 HV _0.025 . Increasing the h‐BN content progressively reduced the hardness to 99 ± 0.92 HV _0.025 at 8 vol% h‐BN, although this value remained higher than that of the unreinforced FSPed Al5083. In contrast, the mean coefficient of friction decreased from 0.496 ± 0.008 for FSPed Al5083 to 0.310 ± 0.005 for the Al5083/92% Al ₂ O ₃  + 8% h‐BN composite. The corresponding specific wear rate decreased from 6.519 ± 0.115 × 10 ⁻⁶ to 4.453 ± 0.074 × 10 ⁻⁶ mm ³ /N·m. These results indicate that increasing h‐BN content improves the tribological performance of the FSPed Al5083‐based surface composites despite the accompanying reduction in hardness.