Wrinkles-assisted nanocrystalline formation and mechanical properties of wrinkled graphene/aluminum matrix composites

摘要

The graphene-reinforced metal matrix composites (Gr/MMCs), prepared by additive manufacturing technology, render a wide range of promising applications. The graphene sheets in Gr/MMCs may get wrinkled during preparation, which renders a significant influence on crystalline texture and deformation behavior. Herein, molecular dynamics models of wrinkled graphene/aluminum (W-Gr/Al) composites are established to study the effect of graphene wrinkle angle on crystal texture of the metallic matrix during the sintering process and mechanical properties of the resulting composites. The results indicate that the sintering temperature significantly affects the molding quality of W-Gr/Al composites, promoting the transformation of sintering mechanism. Furthermore, new wrinkles appear on initially-wrinkled graphene surfaces during the sintering process, resulting in grain boundaries and twin boundaries (TBs), which facilitate the refinement of Al grains. Moreover, uniaxial compression tests reveal that the W-Gr/Al composites sintered at 900 K exhibit the highest Young's modulus and yield strength. It has been demonstrated that the enhancement effect of composite originates from the skeleton network, consisting of wrinkled graphene and TBs. These results provide significant guidance for the design and development of Gr/MMCs.