Laser-offset assisted in-situ Ti/Zr microalloying for grain refinement in Arc-DED fabricated Al-Cu alloy

Arc-directed energy deposition (Arc-DED) enables the rapid fabrication of Al alloys for developing large-scale and lightweight structural components. However, Arc-DED struggles to flexibly regulate the chemical composition, which limits mechanical property enhancement in fabricated components, due to its inherent dependence on commercial welding wires as raw materials. To address this issue, this study proposes a laser-offset assisted in-situ Ti/Zr microalloying strategy. With the laser offset ahead of the arc, the two heat sources generate a synergistic molten pool. The pre-positioned Ti and Zr foils on the top surface of the as-deposited layer are incorporated into this molten pool during subsequent deposition. The laser offset ensures full dissolution of the foils and promotes the formation of L1₂-Al₃(Ti, Zr) phases, which refines grains. Grain boundary strengthening combined with stable work hardening behavior improves tensile strength. This study provides a facile route for fabricating high-strength Arc-DED Al alloys.