The high-temperature oxidation resistance and tribological properties of (FeCoCr)75Ni10(BSi)15−x Ta x high-entropy alloy coating by laser cladding

Abstract (FeCoCr)75Ni10(BSi)15-x Ta x (x = 2, 4, 6) high-entropy alloys (HEAs) coatings are prepared on TC4 substrate using laser cladding (LC), and the high-temperature oxidation (HTO) resistance and tribological properties are studied at room temperature (RT) and high temperature(600 °C). The results showed that at RT, the phase compositions of all coatings primarily comprise the face-centered cubic (FCC) phase, intermetallic compounds, and Laves phase. As a result of solid solution strengthening and the generation of additional hard Laves phase, Ta6 coating demonstrates the highest microhardness (811.9 HV0.2), measuring 2.11 times higher than the substrate(385.7 HV0.2). After 200 h of oxidation, dense and uniform oxide films (composed of TiO2, SiO2, Cr2O3, and CrTaO4) form on the coating surfaces. The surface microhardness is lower compared to RT, where the Ta6 coating decreased to 776.5 HV0.2. However, the oxide films effectively prevent the reaction between the O element and other elements in the coating. Ta6 coating exhibits the least average oxidation rate, approximately 0.75 × 10−3 mg2·mm−4·h−1, and the lowest wear rates of 0.51 and 0.99 mm3· (N·m)−1 at RT and high temperature, respectively, which are reduced by 58% and 67% compared to the substrate. The high-temperature wear mechanisms included abrasive wear, oxidative wear, and adhesive wear. These results demonstrate that the coatings possess excellent tribological performance and HTO resistance, which not only extend the service life of aircraft engine blades but also reduce the post-damage restoration costs of blades.