Wire-Arc Directed Energy Deposition of Aluminum Alloy 7075 With Dispersed Nanoparticles

High-strength Al-Zn-Mg-Cu alloys such as AA7075 have drawn considerable attention and interest from both industry and academia owing to their high-specific strengths and good fatigue resistance. Wire-arc directed energy deposition, an emerging near-net-shape manufacturing technology, faces significant challenges in printing AA7075 due to its hot cracking susceptibility. In this study, we use nano-treated AA7075 wire as feedstock to additively manufacture a crack-free deposition of the high-performance alloy. After T6 heat treatment, the nano-treated AA7075 achieves exceptional yield strength (510.3 MPa), ultimate tensile strength (606.0 MPa), and elongation (12.6%). In addition, nanoparticles homogenize the microstructure upon solidification and inhibit grain growth from cyclic thermal exposure, yielding refined, equiaxed grains throughout the deposition and enabling isotropic mechanical properties in both as-built and T6-treated conditions. Thus, this study highlights a promising intersection of nano-treatment and wire-arc directed energy deposition for printing traditionally unprintable materials.