Enhanced strengthening by wrinkled graphene in copper matrix nanocomposites: a molecular dynamics study

Graphene-reinforced copper (G/Cu) nanocomposites have attracted extensive research interests as promising in developing high strength yet light weight composites. In such composites, however, the weak van der Waals (vdW) interaction mainly dominates interfacial interactions, which considerably hinders their mechanical performance. In this study, wrinkles are constructed on surface of graphene by shear engineering, and their strengthening effect on tensile properties of winkled graphene-reinforced polycrystalline Cu (wG/pCu) nanocomposites is examined by using molecular dynamics (MD) simulations. Extensive MD works demonstrate that wrinkles significantly improve mechanical properties of nanocomposites due to the increased surface roughness. When pre-shear strain γ = 0.2, Young’s modulus and strength of wG/pCu are ~ 105 and ~ 41% enhancement over those reinforced by pristine graphene. Such enhancement is also observed for high-temperature properties and defective tolerance of wG/pCu nanocomposites. With increasing grain sizes of the Cu matrix, tensile strength of wG/pCu decreases, performing an inverse Hall–Petch relationship. This work suggests material design direction—wrinkles on surface of graphene—can effectively alleviate the challenge of weak interaction between graphene and Cu and tailor high-performance G/Cu nanocomposites.