On advanced casting methods for synthesis and improvement of microstructural and mechanical properties of graphene reinforced light metal matrix composites

Graphene nanoplatelet (GNP)-reinforced metal matrix composites (MMCs) represent a groundbreaking group of lightweight structural materials, offering exceptional combinations of strength, toughness, and multifunctionality that are critical for next-generation applications. Graphene imparts exceptional properties that significantly enhance the performance of lightweight alloys such as aluminum and magnesium. The review first examines the <i>ex situ</i> incorporation of GNPs into metal matrices and their effects on alloy solidification and mechanical properties based on process parameters, volume fraction, and matrix material. It then highlights two emerging <i>in situ</i> strategies, including the Covetic process, which employs electrically assisted processing (EAP) to synthesize graphene within metallic melts, and CO₂ bubbling in magnesium alloys to form carbon-metal (C-M) bonds. Particular emphasis is placed on mechanisms of C-M bonding, dispersion challenges, and interfacial bonding between the metallic matrices and graphene. This review emphasizes the potential of graphene-reinforced MMCs across industries and identifies the persistent barriers to process upscaling.