Microscopic strengthening and failure mechanisms of graphene/Al composite: A molecular dynamics study

This study focused on the microscopic strengthening and failure mechanisms of the Al matrix reinforced by graphene (Gr), and the effects of number of layers, chirality, and arrangement of Gr were calculated based on the molecular dynamics simulation. The results revealed that the Young's modulus and yield strength were significantly enhanced by the addition of Gr. In Gr/Al composites with monolayer Gr, the zigzag Gr exhibited a better ultimate strain than the armchair Gr, indicating that the plastic deformation was affected by the chirality, and the dislocation hindrance and load transfer were the dominated strengthening mechanisms. The crack in the armchair Gr was limited to follow straight paths, while that in zigzag Gr extended in a petal-like manner across multiple directions. In Gr/Al composite with multilayer Gr, the dispersing Gr showed a stronger strengthening effect than the stacking Gr, and the strengthening effect increased with increasing the volume fraction of Gr. The dispersing Gr strongly hindered the movement of dislocations, while the Al matrix in the composite with stacking Gr could retard the folding of Gr. Moreover, Gr nanosheets fractured layer by layer rather than simultaneously fractured in the Gr/Al composites with multilayer Gr.