An Overview of Key Challenges in the Fabrication of Metal Matrix Nanocomposites Reinforced by Graphene Nanoplatelets

This article provides an overview of research efforts with an emphasis on the fabrication of metal matrix nanocomposites (MMNCs) reinforced by graphene nanoplatelets (GNPs). Particular attention is devoted to finding the challenges in the production of MMNCs through the powder metallurgy techniques. The main technical challenges can be listed as: (I) reinforcement selection; (II) dispersion of reinforcement within the matrix; (III) reactivity between the reinforcement and matrix; (IV) interfacial bonding; (V) preferred orientation of reinforcement. It is found that some of these difficulties can be attributed to the nature of the materials involved, while the others are related to the preparation routes. It is reported that the challenges related to the process can often be addressed by changing the production process or by using post-processing techniques. More challenging issues instead are related to the composition of the matrix and reinforcement, their reactivity and the dispersion of reinforcement. These topics still bring significant challenges to the materials scientists, and it would be worth mentioning that the fabrication of MMNCs with a uniform dispersion of reinforcement, strong interfacial bonding, without detrimental reactions and improved isotropic properties is still a puzzling issue.