Interface optimization by introducing Ti for strengthening graphene network/copper composites: New insight from MD simulations

The inadequate bonding at the interface between graphene and the Cu matrix has significantly impeded the advancement of graphene-reinforced Cu matrix composites. In this study, Ti was introduced between the three-dimensional graphene network (GN) and the Cu matrix, which effectively strengthened the interfacial bonding by in-situ formation of Cu_xTi_y compounds and TiC with both the Cu matrix and GN. Compared with the GN/Cu composites, the maximum strength and interface separation strain of the GN-TiC-Cu_xTi_y/Cu (GT/Cu) composites are enhanced by 40 % and 275 %, respectively. Molecular dynamics simulations were used to study the strengthening mechanism of the GT/Cu composites. The results show that, the formation of Ti–C bonds, mechanical interlocking, and strong chemisorption significantly enhanced the interfacial adhesion and stress transfer between GN and the matrix, delaying the nucleation and propagation of cracks. On the other hand, the metallic bonds formed between the Cu_xTi_y layer and the Cu matrix further promote the stress transfer between the matrix and the reinforcement, and alleviate the stress concentration in the reinforcement part. In addition, the strengthened interface with dislocation blocking effectively enhances the load-bearing capacity of the Cu matrix. This study provides a new approach for the development of high-strength Cu matrix composites.