Numerical simulation of the influence of alloying elements on welding performance

With the increasingly widespread application of high-strength aluminum alloys, research on the modification of Al-Si brazing filler alloys to achieve high-strength brazed joints has attracted significant attention. However, the lack of theoretical guidance for experimental investigations remains a pressing issue that urgently needs to be addressed. Based on first-principles density functional theory (DFT) calculations, this study investigates the effects of various alloying elements on the brazing performance of AlSi12 filler metal. The research analyzes doping formation energy, charge density, electron localization function (ELF), and integrated crystal orbital Hamilton population (COHP) to elucidate the influences of these elements at the atomic level. The results demonstrate that elements with atomic radii greater than 220 pm (such as Ce, Er, and La) induce lattice expansion, while those with atomic radii less than 180 pm (such as Mg, Ti, and Zn) result in lattice contraction. Elements exhibiting negative doping formation energies include Ce, Cu, Er, La, and Ti, whereas Ag, Mg, and Zn display positive formation energies. Notably, highly oxophilic elements (Ce, Er, and La) are found to enhance interfacial bonding and increase joint strength. This research provides theoretical guidance for the design of alloying compositions in aluminum alloy brazing filler metals.