Enhancing Wear Resistance and Mechanical Behaviors of AA7020 Alloys Using Hybrid Fe3O4-GNP Reinforcement

Abstract

This study investigates the effect of graphene nanoplatelets (GNPs) and milling duration on the microstructure, mechanical properties, and wear resistance of the AA7020 alloy reinforced with Fe3O4 and GNP. The composites were prepared with a fixed 10 wt.% Fe3O4 and varying GNP contents (0.5 and 1 wt.%) using high-energy ball milling for 4 and 8 h, followed by hot pressing. The aim was to enhance the performance of the AA7020 alloy for potential use in defense, automotive, aviation, and space applications, where superior mechanical properties and wear resistance are required. The results showed that the incorporation of 0.5 wt.% GNP and optimized milling significantly improved the composite’s performance. The AA7020 + 10 wt.% Fe3O4 + 0.5 wt.% GNP composite achieved the highest density (99.70%) when milled for 4 h. Its hardness increased with both the inclusion of GNP and extended milling duration, with the composite milled for 8 h exhibiting the highest hardness value (149 HBN). The tensile strength also improved, with the composite milled for 4 h showing a 28% increase (292 MPa) compared with the unreinforced alloy. Additionally, the friction coefficient decreased with GNP content and milling duration, with the composite milled for 8 h showing a 26% reduction. Wear resistance was notably enhanced, with the composite milled for 8 h exhibiting the lowest specific wear rate (7.86 × 10⁻7 mm3/Nm).