Microstructures and properties of graphene-nanoplatelet-reinforced magnesium-matrix composites fabricated by an in situ reaction process

Abstract

Abstract Novel Mg–graphene-nanoplatelet (GNP) composites were fabricated using the Rieke method to synthesize Mg in situ on the GNP surfaces and powder metallurgy (PM). Mg particles synthesized using the Rieke method were deposited on the surfaces of the GNPs during the displacement reaction between Li and anhydrous MgCl2, which yielded in situ Mg-encapsulated GNPs (GNPs@Mg) composite structures. In the GNPs@Mg composite structures, the displaced Mg was closely attached to the surfaces of the GNPs in a nanocrystallite form and achieved a close mechanical interfacial bonding with the GNPs. After employing the PM, the obtained GNPs@Mg composite powders were transformed into GNPs@Mg bulk composites, which ensured the integrity and dispersion of the GNPs in the Mg matrix. The mechanical properties of the GNPs@Mg bulk composite were significantly improved owing to the strengthening effects of the GNPs. The yield strength and ultimate tensile strength of a 1.5-wt.% GNPs@Mg bulk composite were approximately 38.8 and 35.1% higher than those of a pure Mg bulk, respectively, while the hardness and elongation to failure were increased by approximately 47.4 and 36.5%, respectively. Furthermore, the strengthening and toughening efficiencies of the GNPs@Mg bulk composites were significantly higher than those of GNPs/Mg composites fabricated using the conventional addition method. Therefore, this research provides new insights into the process design of high-performance lightweight structural metallic materials.