Preparation of AlTiVNiCu/Cu-Al gradient functional coating via laser cladding for enhanced wear and corrosion resistance of Mg-Li alloy

The poor surface properties of Mg-Li alloys and the excellent comprehensive performance of high -entropy alloy (HEA) coatings are highly complementary. This study uses laser cladding technology to deposit an AlTiVNiCu/ Cu-Al gradient functional coating with favourable wear and corrosion properties on Mg-Li alloy substrates. Through the design of the gradient coating structure, laser cladding is used to coat HEA layers on low -meltingpoint Mg-Li alloys, which effectively reduces further dilution of Mg and Li in the substrate. Notably, the Mg content in the prepared AlTiVNiCu protective layer is only 2.34 %. Furthermore, the microstructure, phase structure, microhardness, tribological and corrosion properties of the gradient coating are systematically studied. The protective layer consists of V -rich BCC1, (Ni, Ti) -rich BCC2, Cu -rich FCC, Mg -rich BCC3 and nanoscale beta-Ti phases, with a predominance of body -centered cubic (BCC) structural phases. The average microhardness is 547.46 HV0.3. Under a load of 3 N, the average friction coefficient of the protective layer is 0.54, with a wear volume of only 2.87 % compared with that of the substrate, which is satisfactory wear resistance. In a 3.5 wt% NaCl solution, the protective layer exhibits the highest corrosion potential (-0.49 VSCE, where SEC denotes saturated calomel electrode), and the lowest corrosion current density (1.14 x 10-6 A & sdot;cm- 2), representing a remarkable enhancement compared with those of the substrate (-1.57 VSCE and 5.41 x 10-4 A & sdot;cm- 2).