Synthesis, characterization, and properties of graphene reinforced metal-matrix nanocomposites

Although significant effort has been made on using graphene as a reinforcement in metal matrix nanocomposites due to its extraordinary high strength and high modulus, metal-matrix graphene nanocomposites still exhibit large scatters in experimentally measured physical and mechanical properties. In this paper, recent progress in research on the synthesis of metal-matrix graphene nanocomposites using powder metallurgy technique involving milling, compaction, and extrusion or rolling with special emphasis on the agglomeration of graphene, interfacial bonding, and reaction between metal-matrix and graphene has been critically reviewed. Strengthening mechanisms such as grain refinement, oxide dispersions, strengthening, impeding of dislocations by reinforcement, load transfer between the matrix and graphene, and CTE mismatch in the metal-matrix graphene nanocomposites has been discussed. Existing theoretical models on the effects of graphene on mechanical properties including tribological behavior will also be discussed and compared with experimental observations. Potential future research directions in the area of graphene-reinforced MMNC will be outlined.