Molecular dynamics simulation of reinforcement mechanism of graphene/aluminum composites and microstructure evolution

Graphene/Aluminum (Gr/Al) composites with different graphene chirality and distribution patterns were established. The contribution of graphene interfaces to the mechanical properties of composites was investigated by using molecular dynamics methods. The composites strengthen about 10% of Young's modulus and 5% of tensile yield strength compared with aluminum. Influenced by the chiral structures of graphene, the fracture strain of zigzag composite is larger, and the yield stress of armchair composite is higher. Folding deformation of graphene promotes the yielding of the composites under compressive loading. Even if the graphene breaks, the graphene interface can effectively limit the dislocation motion, and the twins can only expand around the graphene. The results of both tensile and compressive tests showed that the uniform distribution of graphene was beneficial to enhance the mechanical properties of the composites. Graphene hinders the motion of pre-dislocations more than pinning dislocations. Therefore, the Bauschinger effect of composite is lower than that of pure aluminum under tension-compression loading.