Interface intrinsic strengthening mechanism on the tensile properties of Al2O3/Al composites

Interface plays a crucial role to enhance the mechanical properties of metal-matrix composites. Here, we investigated and modulated the intrinsic characteristics of Al2O3/Al interface through interfacial doping by the first-principles calculations. The Al-terminated Al2O3 (0 0 0 1)/Al (1 1 1) interface with OT stacking was found to be the most stable structure by calculating works of adhesion and interface energies. Then, the first principles tensile experiments were performed on the stable interfacial structure, and the tensile strength and elongation were calculated. It is revealed that there is no direct correlation between tensile properties and the work of adhesion or the interface energy. Systematical analysis on electronic structure indicates that the incorporation of doping elements will redistribute the electrons at the interfaces, and there is the interplay between the uniform electron distribution and the tensile properties, especially the elongation. It is found that Mg-doped and Cu-doped interface systems with more uniform electron distribution show better mechanical properties. Therefore, the interface intrinsic strengthening mechanism caused by the interfacial microstructure has a significant impact on the mechanical properties of the composite materials, and complements the load transfer mechanism in metal matrix composites.