Arc-DED additive manufacturing of high-Zn-content Al-Zn-Mg-Cu alloy assisted by interlayer remelting and mechanical hammering

Arc-directed energy deposition (Arc-DED) is a promising additive manufacturing method for producing medium-to-large-scale and lightweight structural components. The development of high-strength aluminum alloys is crucial for optimizing the performance of these Arc-DED-manufactured components. However, achieving a high tensile strength remains a major challenge for Arc-DED fabricated aluminum alloys. In this work, high-Zn-content Al-Zn-Mg-Cu alloys were fabricated by Arc-DED, with a small amount of TiC and Al₃Ti introduced for grain refinement. In-situ Zn alloying elevates the Zn content to over 9 wt.%, which plays a dominant role in achieving the ultra-high strength. During the Arc-DED process, in-situ Zn alloying is achieved by pre-positioning Zn foil on the top surface of each deposited layer. Interlayer remelting coupled with synchronized mechanical hammering promotes Zn homogenization and improves the forming quality. After T6 treatment, the high Zn content promotes the formation of fine, uniform and high-density nanoprecipitates, resulting in an ultra-high strength of 633 MPa.