Alumina -Reinforced Friction Stir Processing for Enhanced ۶۰۶۱ Aluminum Performance

This study investigates the fabrication and characterization of surface composites on ۶۰۶۱ aluminum alloy using Friction Stir Processing (FSP) with and without alumina (Al₂O₃) reinforcement. The effects of micron- and nano-sized alumina particles on mechanical properties, microhardness, and corrosion resistance were systematically evaluated. FSP was carried out using custom-designed tools and fixtures, and alumina powders were incorporated into the stir zone through a pre-machined groove and zigzag hole pattern. Three processing conditions were explored: FSP without reinforcement (FSP(NP)), FSP with micron-sized alumina (FSP/Al₂O₃(M)), and FSP with nano-sized alumina (FSP/Al₂O₃(N)). The sample reinforced with micron-sized alumina exhibited the highest ultimate tensile strength (۲۱۴ MPa) and yield strength (۱۳۰ MPa), representing improvements of ۲۶% and ۶% over the base alloy, respectively. Microhardness also increased significantly, reaching ۹۰ HV for micron-reinforced samples compared to ۴۶ HV in the base metal. Electrochemical corrosion testing in ۳.۵ wt.% NaCl solution revealed superior performance in the micron-reinforced sample, which exhibited the lowest corrosion current density (۱.۸۸ × ۱۰⁻⁵ A/cm²) and corrosion rate (۰.۲۶۴۵ mm/year), along with the highest polarization resistance (۱۴۷۳ Ω). The findings confirm that FSP enhances the mechanical and corrosion-resistant properties of aluminum alloys, particularly when reinforced with micron-sized alumina. These improvements position FSP as a viable surface modification technique for demanding applications in aerospace, automotive, and marine industries where wear and corrosion resistance are critical.