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With the advancement of laser powder bed fusion (LPBF) for aluminum alloys, developing novel lightweight Al–Li alloy systems present enormous potential for aerospace applications. Conventional Al–Mg–Li alloys exhibit low densities but suffer from poor strength due to the lack of inherent strengthening phases. In the present work, a novel lightweight Al–Mg–Li–Ag-Sc-Zr alloy was developed for LPBF after optimizing the processing parameters. The as-built alloy featured a bimodal microstructure consisting of fine equiaxed grains and columnar grains. The submicron primary Al 3 (Sc, Zr) phases with a cubic L 1 2 structure served as inoculants for grain refinement and exhibited good coherency with the α-Al matrix. Besides, submicron spherical quasicrystalline T-Mg 32 (Al, Ag) 49 phases of and nanometer rod-shaped S 1 –Al 2 MgLi phases were scattered inside the grains. These results produced a yield strength (σ y) of 286 ± 8 MPa, ultimate tensile strength (σ UTS) of 406 ± 3 MPa, and elongation at fracture (ε f) of 12.5 ± 0.3%. The direct aging at 325 °C for 12 h led to an increase in hardness to a peak value of 170 HV. The secondary phases at the grain boundaries were breached and a large amount of submicron T and S 1 phases within the grains were prominently increased. Besides, spherical Al 3 (Sc, Zr, Li) and tiny δ′-Al 3 Li precipitates were observed in the α-Al matrix. A considerably enhanced σ y of 375 ± 12 MPa and σ UTS of 469 ± 4 MPa were achieved mainly due to the particle strengthening but decreased ε f to 5.8 ± 0.2%. The alloys in both states exhibited a moderate work-hardening capability. The feasibility of LPBF for lightweight Al–Li alloy was successfully established but required further optimization of the alloy composition. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel Al-Cu-Li-Mg-Ag-Sc alloy was fabricated by direct energy deposition. • Dual-phase strengthening of Al 3 Sc and T 1 phases can be achieved with a single-stage T6 heat treatment. • The excellent compressive yield strengths achieved 512, 345 and 227 MPa at 20, 200 and 300 °C, respectively. • Al 3 Sc and T 1 phases can maintain strong pinning effects on dislocations. In this work, precipitation and deformation behavior of a novel Al-Cu-Li-Mg-Ag-Sc alloy fabricated by direct energy deposition (DED) were investigated in detail. Dual-phase strengthening of Al 3 Sc and T 1 (Al 2 CuLi) phases can be achieved with a single-stage T6 heat treatment compared to normal double-aging. The excellent compressive yield strengths achieved 512, 345 and 227 MPa at 20, 200 and 300 °C, respectively. Al 3 Sc and T 1 phases can maintain strong pinning effects on dislocations, suggesting a good work hardening ability during deformation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Quasi-crystalline T 2 phase precipitates for 2A97 Al-Li alloy produced by laser additive manufacturing. • Under influence of thermal cycle, T 2 phase transforms into face-centered cubic Y phase. • T 2 phase turns into O phase with orthorhombic at 515 °C for 1.5 h during solution treatment. Precipitated phases of 2A97 Al-Li alloy fabricated by laser additive manufacturing with thermal input are mainly composed of quasicrystal T 2 phase gathered around grain boundary and T B phase in grain interior. Diffraction patterns of quasi-crystalline T 2 phase show two-fold, three-fold and five-fold symmetry, respectively. Under condition of thermal cycling, T 2 phase transforms into a face-centered cubic Y phase with a lattice constant of 2 nm. Y phase can grow into twins, and the twin plane is (1 1 1). After solution treatment at 515 °C for 1.5 h, δ' phase, T 1 phase and T B phase are completely dissolved in matrix, while quasi-crystalline T 2 phase transforms into orthorhombic O phase. The size of O phase is similar to that of T 2 , with length of about 400 nm and rougher surface. [ABSTRACT FROM AUTHOR]