Influence of Al2O3 addition on microstructure, mechanical strength, and wear behavior of AA7075- Al2O3 matrix composites fabricated using deformation-driven metallurgy

• AA7075- Al₂O₃ matrix composites fabricated using deformation-driven metallurgy. • Grain size decreases up to 16 wt. % Al₂O₃ but increases at higher concentrations due to agglomeration. • Hardness rises with Al₂O₃ content, but excessive addition (32 wt. %) reduces tensile strength due to particle clustering. • The lowest wear rate (4.3 ± 0.3 µg/m) and optimal friction coefficient (0.38 ± 0.04) occur at 8 wt. % Al₂O₃. This study investigates the impact of Al₂O₃ addition on the microstructure, mechanical properties, and wear behavior of AA7075-Al₂O₃ composites processed through deformation-driven metallurgy. It addresses a critical gap in understanding the relationship between alumina content and composite performance, particularly regarding grain size, strain accumulation, and wear resistance. The results show that grain size decreases with increasing Al₂O₃ content up to 16 wt. % (5.2 ± 1.1 µm), but increases at higher concentrations (6.4 ± 0.8 µm at 24 wt. % and 6.8 ± 0.9 µm at 32 wt. %). X-ray diffraction analysis revealed a peak in strain accumulation at 8 wt. % Al₂O₃ (0.3245), followed by a decrease at higher concentrations, suggesting that excessive alumina limits dislocation mobility. Scanning electron microscopy confirmed a uniform distribution of alumina at 8 wt. % Al₂O₃, leading to strong particle-matrix bonding, while higher concentrations caused agglomeration and interfacial discontinuities. Hardness increased with Al₂O₃ content, reaching 326.8 ± 21.5 HV₀.₁ at 32 wt. % Al₂O₃. However, tensile strength decreased at 32 wt. % Al₂O₃ (462.5 ± 10.7 MPa) due to particle agglomeration. The wear rate was lowest at 8 wt. % Al₂O₃ (4.3 ± 0.3 µg/m), with an optimal friction coefficient of 0.38 ± 0.04. This study fills the gap in understanding the effect of Al₂O₃ content on the mechanical and tribological properties of AA7075 composites and demonstrates their potential for high-strength and wear-resistant applications.