Experimental Investigation on the Effect of Graphene/Al2O3 Reinforcements on the Microstructural, Mechanical, and Tribological Characteristics of AZ91 Alloy

Abstract In the present work, the effect of graphene/Al2O3 on the microstructure, mechanical, and wear characteristics of AZ91 alloy was studied. The composites with various proportions of graphene/ Al2O3 are prepared using inert gas-assisted stir-casting technique. The scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) mapping investigation exhibited that the reinforcing elements were uniformly distributed inside the matrix structure. The composite's hardness increased from 62HB to 86HB with the incorporation of reinforcements. The hybrid composite (AZ91 + 1 wt% graphene + 2 wt%Al2O3) demonstrated a significant enhancement in ultimate tensile strength (UTS), yield strength (YS), and compressive strength (CS), with enhancements of 39.01%, 59.26%, and 52.17%, respectively, as compared to the AZ91 alloy. From wear test results, it is observed that the hybrid composites demonstrate greater wear resistance compared to the AZ91 alloy. At a load of 30 N, the wear rate (WR) of the hybrid composite (HC3) was 79.10% lower than that of pure AZ91, indicating a greater improvement in wear resistance. Further, the SEM analysis identified delamination, abrasion, oxidation, and adhesion mechanisms on the worn surface.