Effect of element N on microstructure and tribological properties of CoCrFeNiV alloy at severe temperature

Abstract

In this study, CoCrFeNiV non-equiatomic high entropy alloys (HEAs) with varying N content were prepared using vacuum hot-press sintering. The effects of N content on the alloy's microstructure, mechanical properties, and tribological behavior at different temperatures were investigated. The results indicate that the N-added alloys primarily maintain an FCC phase. With increasing N content, the σ phase in the alloy gradually decreases, while the VN content increases, leading to grain refinement. This results in a 10.7% increase in hardness, a 9% increase in compression strength, and a 56% increase in compression deformation. Below 400°C, the primary wear mechanisms are adhesive wear, spalling wear, and slight oxidative wear, while above 600°C, oxidative wear dominates. The addition of N reduced the wear rates of the alloy by 33.8%, 8.1%, and 31.3% at RT, 200°C, and 600°C, respectively, and decreases the coefficient of friction at all temperatures. In summary, N addition improves the alloy's tribological performance at various temperatures.