Effect of reinforcement amount on the microstructural and mechanical properties of mechanically alloyed graphene nanoplatelet reinforced Al-3.5 wt% Cu composites

In this study, various amounts (0.25, 0.5, 0.75, 1, and 2 wt%.) of graphene nanoplatelets (GNPs) reinforced Al-3.5 wt% Cu metal matrix composites were produced using powder metallurgy processes consisted mechanical alloying and pressureless sintering. To compare the properties of the sintered composites, as-blended and 4 h mechanically alloyed powders were sintered to yield Al-3.5 wt% Cu matrix alloys. The microstructural, thermal and mechanical properties were examined using relevant characterization techniques. The formation of Al₂Cu phase was detected at all XRD patterns of the sintered samples other than matrix and reinforcement phases. Mechanically alloyed powders exhibit the equiaxed particle morphology compared to the as-blended ones, their mechanical properties were found better than as-blended and sintered samples. Additionally, mechanical alloying led to the dispersion of GNP reinforcements into the Al[sbnd]Cu matrix. The highest hardness value (around 153 HV) was obtained for 2 wt% GNP reinforced composite. The highest wear resistance was recorded for 1 wt% GNP reinforced composite with 2.07 ± 0.2 mm³/N.m×10⁻³ wear rate. Additionally, composites' compressive strength improved with adding 1 wt% GNP (∼68.5 MPa). The good dispersion of the optimum amount of GNP's via mechanical alloying provide to obtain preferable mechanical properties.