Effect of Y2O3 on the microstructure and tribology property of WMoTaNb refractory high entropy alloy coating prepared by laser cladding

Recently, high-entropy alloys (HEAs) reinforced with ceramic particles have attracted increasing attention due to their excellent hardness and wear resistance. In this study, the WMoTaNb-Y2O3 refractory high-entropy alloy coatings were produced on Inconel 718 by laser cladding to improve the microhardness and high-temperature wear resistance of the substrate. The phase composition, microstructure, and mechanical properties of the HEAs were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), microhardness, and wear resistance tests. The results show that due to the high entropy effect and elemental diffusion, the WMoTaNb-Y2O3 refractory high-entropy alloy coatings comprise simple BCC and Fe-containing phases. Y2O3 particles are mainly distributed at the surface of the high-entropy alloys coatings. Y2O3 particles have an advantage in the inhibition of HEAs grain growth attributed to a strong pinning effect. The microhardness and the wear resistance of the HEA composite improved significantly with the addition of Y2O3 particles. A good comprehensive mechanical properties was obtained at the HEA with the addition of 3 wt% Y2O3 particles, which microhardness can reach to 1274.6 HV0.2. The laser-cladded WMoTaNb-Y2O3 high-entropy alloy coatings show a good wear performance at high temperature, which is mainly attributed to the formation of oxide films on the surface of the coating. The wear mechanisms are dominated by abrasive wear, adhesive wear and oxidative wear. The HEAs coating with 3 wt% Y2O3 has the best tribological performance at 800 °C with the minimum friction coefficient is around 0.4 and the minimum wear rate of only 0.58 × 10−5 mm3/Nm, respectively.