Synthesis and microstructure, properties characterization of Ni-Ti-Cu/Cu-Al functionally graded coating on Mg-Li alloy by laser cladding.

[Display omitted] • Ni-Ti-Cu/Cu-Al functionally graded coating was prepared on Mg-Li alloy by laser cladding. • The graded coating was constructed to solve the problem that the influence of evaporation and dilution about Mg and Li elements on the performance of coating. • Typical hypoeutectic structure composed of Li 3 Mg 7 and CuMg 2 was obtained in the interlayer (Cu-Al). • The corrosion and wear resistance of Mg-Li got huge improvement. The bottleneck challenge of preparing laser cladded coating on Mg-Li alloys is the evaporation and dilution of substrate, which seriously affect the performance of coatings. In order to solve these deficiencies, Ni-Ti-Cu/Cu-Al functionally graded coating was proposed in this work. The graded coating with excellent performance was successfully prepared on Mg-Li alloy. More remarkable, the top-layer was not affected by dilution and substrate evaporation. The top-layer was mainly composed of Ni 3 Ti and NiTi intermetallic compounds, as well as TiNi 0.8 Cu 0.2 phase that dispersed on the surface of Ni 3 Ti. Typical hypoeutectic structure was found in the interlayer, which was composed of Li 3 Mg 7 and CuMg 2. Furthermore, the corrosion and wear resistance of Mg-Li alloy were greatly improved. Specifically, the wear volume of the top-layer and interlayer is reduced by 98.04% and 82.41% than that of substrate, respectively. The corrosion potential of the top-layer (-242 mV) and the interlayer (-991 mV) are 1311 mV and 562 mV higher than that of the substrate (-1553 mV), while the corrosion current density of the top-layer (2.71 × 10-7 A·cm−2) and the interlayer (1.93 × 10-6 A·cm−2) are about three and two orders of magnitude lower than that of the substrate (2.53 × 10-4 A·cm−2). [ABSTRACT FROM AUTHOR]