Microstructure and mechanical properties of wire arc additively manufactured 205A high strength aluminum alloy: The comparison of as-deposited and T6 heat-treated samples

In this study, the microstructure and mechanical properties of wire arc additive manufactured 205A high strength aluminum alloy were investigated. The samples in both the as-deposited (AD) condition and the T6 heat-treated (T6) condition were compared. The formed heterogeneous nucleation particles such as Al3Zr and Al3Ti promoted the formation of fine equiaxed grains with a low heat input. Some eutectics were dissolved during the solid solution process, with the appearance of secondary pores. A part of Cd was observed at the edge of the needle-like θ' phase, by transmission electron microscopy (TEM). In the subsequent aging process, the Cd atoms, vacancies, and Cu atoms formed Cu-Cd-vacancy clusters with lower activation energy than Cu atoms. Hence, the precipitation of the θ' phase was further promoted, which significantly improved the mechanical properties. The ultimate tensile strengths in the horizontal and vertical directions appeared isotropic and reached 510.2 MPa and 510.6 MPa, respectively. However, the eutectics and aggregated pores in the inter-layer regions resulted in the anisotropy of elongation.