Dislocation-blocking mechanism for the strengthening and toughening of laminated graphene/Al composites

Graphene/aluminum (Gr/Al) nanolaminated structures have a great reinforcing and toughening effect in Al composites. The graphene layers effectively impede the growth and movement of dislocations in the Al matrix. Therefore, more and shorter dislocation-lines occur in the Al matrix in-between graphene layers. In this paper, compression tests were performed on Gr/Al nanolaminated composites using molecular dynamics (MD) to study the dislocation-blocking mechanism of the reinforcing and toughening effect. Strength and strain at the yield point as well as the yield mode for Gr/Al nanolaminated composites were obtained. Nucleation, expansion, and movement of dislocations in the Al matrix under compression were investigated. The results reveal that the reinforcing mechanism involves the increase of dislocation density and shear-stress transfer. At the same time, the toughening mechanism can be explained with a decrease of the plastic-strain rate. Moreover, the reinforcing and toughening effects as a function of spacing-distance of the graphene layers was also investigated. Furthermore, we also explored the changing properties of Gr/Al composites for different Al lattice orientations.