Effect of Graphene Nanoplatelets Content on the Mechanical and Wear Properties of AZ31 Alloy

Abstract

Graphene, as a rising-star materials, has attracted interest in fabricating lightweight self-lubricating metal matrix composites with superior mechanical and wear properties. In this work, graphene nanoplatelets (GNPs) reinforced AZ31 alloy composites were fabricated by a powder metallurgy technique and then a hot extrusion. The effects of GNPs content (0.5, 1.0, and 2.0 wt.%) on the microstructures, mechanical properties, and wear performance of the extruded GNPs/AZ31 composites were studied. It was found that the addition of GNPs resulted in a weakened basal plane texture and grain refinement of the AZ31 matrix metal. Less than 1.0 wt.% GNPs in GNPs/AZ31 composites resulted in the enhancement in both Vickers hardness and tensile yield strength with acceptable elongation. The Vickers hardness and tensile yield strength of 1.0GNPs/AZ31 composite increased by 4.9% and 9.5% respectively, compared with the unreinforced AZ31. Moreover, the elongation of the composites was about the same as the AZ31 base alloy. Both the friction coefficient and the wear mass loss continuously decreased with the increasing GNPs content, which exhibited a self-lubricating effect. The relationship of the friction coefficient and wear mass loss with the GNPs content could be modeled in terms of the Holliday model and the exponential decay model, respectively. The worn surface morphology revealed that adhesive wear and abrasive wear simultaneously acted in AZ31 alloy. Nevertheless, abrasive wear became the dominant wear mechanism in the GNPs/AZ31 composites.