An investigation of the mechanical properties and deformation of graphene/metal composites by molecular dynamic simulations

Metal matrix composites (MMCs) have attracted a great deal of research interest because they have better mechanical and physical properties than pure metals. The extraordinary mechanical properties of graphene make it very suitable for reinforcing components in MMCs. Although a lot of investigations have been carried out to introduce graphene into the metal matrix, there has been no systematic research into the mechanical performance of graphene/metal composites at an atomic level. In this thesis, molecular dynamics (MD) simulations are used to investigate the mechanical properties and deformation behaviour of graphene/metal composites. This thesis focuses on nano-layered graphene/Cu composites. The results indicate that a larger volume fraction of graphene enhances the Young’s modulus and tensile strength of composites, but it results in a lower yield strain. A ‘negative Poisson’s ratio’ behaviour of composites is observed under uniaxial tension, which is explained by the enhanced surface effect and inhomogeneous distribution of stress caused by the graphene/Cu interface. Furthermore, a simultaneous positive and negative Poisson's ratio can be obtained in an asymmetric composite because graphene has a good blocking effect. An alternating composite consisting of multilayer graphene and thin Cu films is proposed to overcome the limitations of scale, and its negative Poisson's ratio persists when the total thickness is over 100 nm. Nanolayered graphene/Cu composites with adjustable Poisson's ratio may have potential applications in scaffold design and telecommunication cables.