Investigation of through-thickness anisotropy in 2195 A l-Li alloy fabricated by additive friction stir deposition

Additive Friction Stir Deposition (AFSD), as a novel solid-state additive manufacturing process, has demonstrated significant potential in fabricating lightweight aluminum alloys, thereby emerging as a rapidly developing manufacturing method. However, when utilizing AFSD to manufacture thicker components, notable through-thickness anisotropy arises due to the varying thermal cycles and pressures experienced by each layer of the alloy. In this study, 14-layer samples were fabricated from as-rolled 2195 A l-Li alloy using AFSD, and the differences in microstructure and properties across varying thicknesses of the samples were investigated. Microstructural characterization revealed that θ phase predominated throughout the sample. The T1 phase precipitated within the upper-layer material, with fine and dispersed precipitates and an inconspicuous precipitation-free zone at grain boundaries, resulting in superior strength (246/417 MPa) and ductility (22%). Compared to the bottom-layer material, the strength increased by 68.5%, and the elongation improved by 20%. The findings of this study indicate that when employing AFSD to manufacture 2195 A l-Li alloy components, the influence of thickness dimension on component performance must be considered, and thin-walled components are more prone to achieving an excellent combination of strength and ductility.