Atomic-scale simulations of the interfacial mechanical properties of Al/AlCu intermetallic compounds

The dynamic evolution and the mechanical properties of Al–Cu interfacial microstructures hold considerable scientific and technological significance. This study explores the mechanical behavior of Al/AlCu intermetallic compound (IMC) layered composites using the NEP machine learning molecular dynamics simulation method, with a focus on the bond strength between the Al matrix and various AlCu alloy interfaces. The Al/Al₂Cu/Al and Al/Al₄Cu₉/Al composite systems exhibit significantly enhanced bond strength, resulting in an overall improvement in their mechanical properties. The ordered atomic arrangement of Al–Cu at the interface effectively regulates stress distribution. Notably, the strength of θ′-Al₂Cu is found to increase by approximately 30% compared to the pure polycrystalline Al system. In contrast, the Al₃Cu IMC interface results in reduced bond strength between the Al matrix and the interface due to its poor structural stability, leading to a larger damage region at the grain boundary-Al₃Cu interface. Under high-strain-rate conditions, the Al₂Cu IMC interface is compressed by the polycrystalline Al along the z-direction, leading to greater distortion at the interface.