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• La 2 O 3 improved the temperature gradient and reduces crack susceptibility. • La 2 O 3 promoted nucleation and grain refinement and increases dislocation density. • La 2 O 3 doping increased the hardness of the coating and improved the wear pattern. In this study, CoCrFeNiMoSi and CoCrFeNiMoSi + 0.5 % La 2 O 3 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 La 2 O 3 resulted in the refinement and uniformity of the CoCrFeNiMoSi + 0.5 % La 2 O 3 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 La 2 O 3 has significant potential in enhancing the friction and wear performance of HEA coatings. [ABSTRACT FROM AUTHOR]

To strengthen face-centered cubic structured high entropy alloys, this paper explores a new method of ceramic reinforced CoCrFeNiMo 0.2 high entropy alloy composite gradient coating. In this study, four sets of gradients were created by first preparing a pristine alloy coating without silicon carbide content on the substrate, followed by preparing composite coatings with varying silicon carbide mass fractions (8 %, 16 %, 24 %) on the pristine coatings. The coatings were then analyzed for their phase composition, microstructure, microstructure evolution process, and friction wear properties. The study reveals that the microstructure of the initial alloy coating consists of a single-phase face-centered cubic solid solution. It is observed that intragranular segregation occurs in the coating, resulting in the boundary enrichment of Mo and Cr elements. As the silicon carbide addition increases, the segregation behavior becomes more pronounced, and the generation of body-centered cubic phase is observed. The second, third, and fourth layers exhibit significantly higher average hardness, measuring at 594 HV, 722 HV, and 788 HV respectively. This can be attributed to the presence of body-centered cubic structure, carbide, and grain boundary strengthening effects. On average, the hardness of these layers is three to four times higher than that of the first layer. With an increase in the number of layers, the wear mechanism changes from adhesive wear to abrasive wear. The wear rates of the second, third, and fourth layers were all reduced by at least 87 % compared to the first layer. However, there were different forms of abrasive wear observed between these layers. The findings of this study have significant engineering implications. • The microstructural evolution of columnar grains to equiaxed dendrites was studied. • The high-density of dislocations enhances the diffusion of Mo and Cr elements. • The tissue shows phase separation act containing the BCC structure. • The shift behavior of the wear mechanism of the gradient structure was studied. [ABSTRACT FROM AUTHOR]