A systematic study of interface properties and fracture behavior of graphene/aluminum: Insights from a first-principles study

In-depth study of graphene/aluminum interface properties with different structures is of great significance for improving the toughness and strength of next-generation aluminum alloys. In this paper, different structural models of Al matrix and graphene/Al composites were studied by first-principles calculations, revealing the interface strength and fracture behavior mechanism. The stability, fracture energy and tensile strength of different surfaces of Al(1 0 0), Al(1 1 0), and Al(1 1 1) were investigated by first-principles calculations, and the interfacial strength and fracture behavior of three common surfaces were revealed. The Al(1 1 1) surface has the lowest surface energy, lowest fracture energy and lowest tensile stress intensity. On this basis, we considered coating graphene on Al(1 1 1) surface, and then investigated the effects of C vacancies and Si doping on the fracture energy and tensile strength of the composites. The results show that with the increase of C vacancies and the increase of Si introduction concentration, the fracture energy and tensile stress strength of the system tend to increase. The density of states calculations show that there is a certain hybridization effect between Al-3s, Al-3p and C-2p, Si-3p orbitals, forming s-p hybrid orbitals. The most stable interfaces contain low-energy state electrons with the most uniform electron distribution, which is a key factor for interface stabilization and strengthening. Our theoretical research results have certain guiding significance for the experimental synthesis of graphene-reinforced aluminum matrix composites and the improvement of the strength of aluminum and aluminum alloys.