Study on the Microstructure and Mechanical Properties of Al–Cu–Mg Aluminum Alloy Based on Molecular Dynamics Simulation

The solidification process and uniaxial tensile test of Al–Cu–Mg alloy at the atomic scale were studied using the molecular dynamics method. The influence of the Mg/Cu ratio on the microstructure and mechanical properties of the Al–Cu–Mg alloy was investigated. The results indicated that during the solidification, the diffusion coefficient of Mg atoms was the lowest, while that of Al atoms was the highest. There may be strong bonding and strong chemical short range ordered structures between Mg–Mg, Al–Cu, and Mg–Cu atoms. As the uniaxial tensile progressed, the alloy exhibited a transformation of FCC→BCC→HCP phase. With increase of the Mg/Cu ratio, HCP and FCC layer-like phases gradually appeared, promoting the occurrence of twins and stacking faults, which resulted in dislocation slip and stress relaxation. As a result, the material become more prone to deformation, leading to a reduction in tensile strength.