A novel laser-cladded AlCuTiVCr/Cu-Al functionally graded coating with excellent corrosion resistance on Mg-Li alloy.

• A metallurgical AlCuTiVCr HEA coating was prepared on Mg-Li alloy. • Cu-Al layer can balance the thermal matching disparity among HEA layer and Mg-Li. • HEA coating consists of (V, Cr)-rich BCC 1 , Mg-rich BCC 2 , AlCu 2 Ti and β-Ti phases. • The corrosion resistance of Mg-Li alloy was significantly improved. AlCuTiVCr/Cu-Al lightweight high-entropy alloy gradient coating was successfully prepared by laser cladding to improve the corrosion resistance of Mg-Li alloy. The boundaries between AlCuTiVCr protective layer, Cu-Al transition layer and Mg-Li alloy substrate are distinct, forming an excellent metallurgical bonding. The gradient coating design has effectively balanced the thermal matching difference between HEA coating. The prepared AlCuTiVCr protective layer comprises (V, Cr)-rich BCC 1 , Mg-rich BCC 2 , AlCu 2 Ti and β-Ti phases. The Cu-Al transition layer is composed of β-Li, Cu 2 Mg and Al 2 Cu 3 phases. The corrosion potential of AlCuTiVCr protective layer (−0.46 V SEC) is 1.09 V SEC higher than that of Mg-Li alloy (−1.55 V SEC), while the corrosion current density of the protective layer (9.41 × 10−7 A cm−2) is about three orders of magnitude lower than that of the substrate (5.97 × 10−4 A cm−2). [ABSTRACT FROM AUTHOR]