Effect of rare earth La2O3 on the microstructure and tribological properties of laser-clad CoCrFeNiMoSi high-entropy alloy coatings

In this study, CoCrFeNiMoSi and CoCrFeNiMoSi + 0.5 % La2O3 High entropy alloy (HEA) coatings were prepared by laser cladding. The microstructure was consisted mainly of body-centered cubic structure, face-centered cubic structure and intermetallic compounds of Si. The addition of rare earth La2O3 resulted in the refinement and uniformity of the CoCrFeNiMoSi + 0.5 % La2O3 HEA coating grains, leading to an increase in microhardness from 430 HV to 520 HV. Additionally, the friction coefficient decreased by 0.15 and the wear rate decreased by 2/3. These findings indicate that the appropriate addition of La2O3 has significant potential in enhancing the friction and wear performance of HEA coatings.