Improving the microstructure and properties of 205A alloys fabricated by wire-arc directed energy deposition using ultrasonic impact treatment

205A aluminum alloy was fabricated by wire-arc directed energy deposition (WA-DED) with and without ultrasonic impact treatment (UIT). The results indicated that UIT could lead to a large plastic deformation, improving surface forming quality and reducing internal porosity. Additionally, UIT facilitated the transformation of columnar grains into equiaxed grains, reducing the average grain size from 25 μm to 17 μm. After UIT, the mechanical properties improved, with ultimate tensile strength (UTS) and elongation (EL) reaching 255 MPa and 19% in the horizontal direction, and 245 MPa and 16% in the vertical direction, respectively. No significant anisotropy was observed.