The process optimization, wear and corrosion properties of WTaNbMo refractory high-entropy alloy coatings by laser cladding

In this study, WTaNbMo refractory high-entropy alloy (RHEA) coatings were successfully fabricated on Inconel 718 substrate by laser cladding. Optimal coatings with superior comprehensive performances were systematically identified through orthogonal experimental design and Radar chart analysis. The phase composition, microstructural evolution, tribological behavior, and corrosion resistance of the RHEAs were comprehensively investigated, with emphasis on the effect of laser energy density (Led) on coating properties. The coatings predominantly consist of body-centered cubic (BCC), γ-(Ni, M) solid solutions, and Fe7(Nb, Ta)3 intermetallic compounds, attributed to high entropy effects and elemental diffusion. The results indicated that Led significantly influenced the thermal behavior of molten pool, thereby regulating solidification rate, elemental distribution, microstructural uniformity, and defect formation. At an optimized Led of 16.67 J/mm2, the coating exhibited a dense and homogeneous microstructure with reduced segregation and fewer defects, leading to a 304.45 % increase in microhardness compared with the substrate. The enhanced tribological performance was attributed to the synergistic effects of grain refinement, BCC solid-solution strengthening, improved coating densification, and enhanced deformation resistance, resulting in the lowest wear rate at room-temperature (RT). Electrochemical and immersion corrosion tests further demonstrated that the optimized Led improved corrosion resistance, as evidenced by lower corrosion current density, higher charge-transfer resistance, and a 33.33 % reduction in corrosion rate compared with the substrate. This improvement was mainly related to the formation of a more compact coating structure and stable passive films that effectively inhibited Cl− penetration.