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For Sc-containing Al-Li alloys, Al 3 Sc precipitates exhibited inhomogeneous distribution due to limited solid solubility, segregation and sluggish diffusion of Sc. Laser rapid melting (LRM) with its merit of increasing the solubility of alloying elements during solidification represents a pivotal technique for exploring new alloy compositions. In this study, microstructure evolution and aging precipitation behavior of a novel Al-Li-Cu-Mg-Ag-Sc alloy fabricated by LRM were investigated during a systematically optimized T6 heat treatment. No primary Al 3 Sc particles were formed during the rapid solidification, but coherent Al 3 Sc nanoparticles were precipitated in the subsequent cooling process. Maximum hardness of 202 HV was achieved after aging at 175 °C/18 h due to combined precipitation strengthening of the Al 3 Sc, δ', Al 3 (Li, Sc) and T 1 phases. Coherent Al 3 Sc was concerned with a sequence of atomic displacement modulations that led to varying degrees of {002} Al planar collapse, while interfacial dislocations were emitted from the interface of Al 3 Sc with coherency lost. The existing Al 3 Sc phases were available to be acted as nucleation sites for δ′ and T 1 to form composite phases. These results can provide indispensable information for compositional design of novel Al-Li alloy specifically for laser additive manufacturing. • A novel Al-Cu-Li-Mg-Ag-Sc alloy was fabricated by laser rapid melting. • The maximum hardness achieved 202 HV for the peak-aged alloy. • The precipitates of peak-aged alloy were Al 3 Sc, δ', Al 3 (Li, Sc) and T 1 phases. • Al 3 Sc was formed by atomic displacement modulations inducing {002} Al plane collapse. • Al 3 Sc would act as the nucleation sites for δ′ and T 1 to form composites. [ABSTRACT FROM AUTHOR]

• The AMF with different densities was prepared by liquid-liquid interface self-assembly method. • A series of AMF@SiO 2 @NaYbF 4 : 2%Er3+ composite structures were constructed to enhance UC emission intensity of Er3+ ions. • The UC emission intensity of the single NaYbF 4 : 2%Er3+ microdisk was enhanced by 6.98 time. • The physics mechanism of the plasmon-enhanced UC luminescence is carefully studied. [Display omitted] Harnessing the precious metal plasmon effect is a powerful way to enhance the upconversion luminescence of rare-earth materials, so it has received extensive attention from researchers. In this study, a series of AMF@SiO 2 @NaYbF 4 : Er3+ composite structures were constructed with an Au mono-layer film (AMF) as the substrates and SiO 2 as the isolation layer to enhance the upconversion emission intensity of a single NaYbF 4 : 2%Er3+ microdisk. When the size of Au nanoparticles was 72 nm and the thickness of the SiO 2 isolation layer was 24 nm, the upconversion emission enhancement factor of the single NaYbF 4 : 2%Er3+ microdisk reached 6.98 under 980 nm laser excitation, due mainly to the enhancement of the local electromagnetic field. The upconversion luminescence properties of a single NaYbF 4 : 2%Er3+ microdisk were significantly affected by the size of Au nanoparticles, the density of the AMF substrate, and the thickness of the SiO 2 isolation layer. The plasmon-enhanced upconversion luminescence mechanism was studied according to its luminescence properties, dynamic tests, and theoretical simulation. The synergistic effects in the local electromagnetic field, luminescence quenching, and local surface plasmon resonance effect are also discussed. The results of this research provide an invaluable theoretical basis for enhancing the upconversion luminescence of rare-earth materials with the help of AMF substrates. [ABSTRACT FROM AUTHOR]