Grain Refinement of CoCrFeNiMn High-Entropy Alloy for Improved High-temperature Tribological Properties

Abstract

CoCrFeNiMn high-entropy alloys (HEAs) are renowned for their exceptional ductility but their broader application is limited by poor wear resistance. Herein, ultrasonic shot peening (USP) was employed to perform surface enhancement treatments on CoCrFeNiMn high-entropy alloys, and their friction behavior from room temperature up to 600°C was studied. Friction testing demonstrated that USP significantly enhances tribological performance over a wide temperature range. Notably, at 600°C, USP-treated samples exhibited a reduced coefficient of friction of 0.41 and a 66.6% decrease in wear rate from 1.86×10^-4 to 6.21×10^-5 mm³/Nm. Detailed analysis reveals that USP not only increased dislocation density but also introduced a grain-refined layer. Additionally, it facilitated a transition from a singular FCC phase to a multiphase structure predominantly composed of FCC, with minor phases of HCP and BCC, substantially enhancing wear resistance.