Effect of LaB₆ on the microstructure and wear resistance of In718/LaB₆ composite coatings by laser cladding

In this study, In718/LaB₆ composite coatings with LaB₆ content of 0–8 wt% were prepared on In718 substrate by laser cladding method, and the mechanism of LaB₆ strengthening of In718 nickel-based high-temperature alloy was investigated by studying the phase composition, microstructure, microhardness, and wear resistance of the coatings. The results show that the addition of LaB₆ reduces the G/R ratio and promotes the formation of equiaxed grains. The best wear resistance was achieved at 6 wt% of LaB₆, with a wear rate of 4.59 × 10⁻⁴ mm³/N m. The maximum microhardness of the coating was achieved at 8 wt%, with an increase of 52.7% in the average microhardness as compared to that of the substrate. However, the excessive addition of LaB₆ promotes a non-uniform tissue distribution, which negatively affects the wear resistance of the coatings.