Study on the Friction and Wear Properties and Mechanism of Nb‐Doped CoCrFeNi High‐Entropy Alloy

This study examines the impact of ball milling control agents on the microstructure, tensile strength, and tribological properties of CoCrFeNi–Nb high‐entropy alloys (HEAs) fabricated via spark plasma sintering. The incorporation of Nb facilitates the formation of a Laves hard phase within the CoCrFeNi HEA matrix. At the same time, the addition of 0.1%wt stearic acid significantly enhances the dispersion of the Laves phase and tensile strength. Friction and wear tests demonstrate a notable enhancement in the wear resistance of the material upon the addition of Nb. Specifically, the wear rate decreases progressively from 0.342 × 10 −3 mm 3 (N m −1 ) in the absence of Nb doping to 0.213 × 10 −3 mm 3 (N m −1 ) when doped with 7%wt Nb. For the CoCrFeNi alloy, significant fluctuations in the friction coefficient are observed at 200 r, with abrasive wear being the predominant wear mechanism. As the rotational speed and load increase, the friction coefficient stabilizes, and the wear mechanism transitions from abrasive wear to oxidative wear and adhesive wear. For the CoCrFeNiNbx HEA, the fluctuation amplitude of the friction coefficient increases with higher Nb content, whereas the wear rate decreases. The predominant wear mechanism in the CoCrFeNiNb HEA shifts from abrasive wear in the absence of Nb to adhesive wear.