Tribological performance of a TiZrNbMo_0.6 refractory high entropy alloy at elevated temperatures

Refractory high-entropy alloys (RHEAs) have attracted extensive attention in the field of high-temperature for their excellent high-temperature resistance, mechanical properties, and wear performance. One kind of RHEAs, e.g., Ti-Zr-Nb-Mo, is a potential candidate for wear-resistant materials due to its high strength and low modulus. In this study, the microstructure, oxidation resistance, tribological properties and mechanisms of TiZrNbMo_0.6 RHEA were studied. SEM and EDS were used to characterize the morphology and compositions of the wear surfaces and cross-sections, as well as the Si₃N₄ counterparts. The results indicate that the TiZrNbMo_0.6 alloy has the optimal wear resistance due to forming a compacted and continuous glaze layer on the surface at the temperature of 500 °C. The evolution of the wear mechanism at different temperatures has been discovered and the oxidation test has been conducted to explain the mechanisms of tribological properties at high temperatures. The dominate wear mechanism changes from abrasive wear and adhesive wear at room temperature to oxidative wear and slight abrasive wear at 500 °C. With the wear temperature increasing to 800 °C, the dominate wear mechanism is severe oxidative wear, and followed partly abrasive wear, which results in a higher wear rate at 800 °C than that at 500 °C.