Improved Wear Resistance of High-Entropy Alloy Composite Coatings Reinforced With Cr3C2 Carbide via Laser Cladding

Abstract

Abstract. In an effort to acquire harder and more wear-resistant FeCoCrNiMn high-entropy alloys, the Cr3C2-reinforced FeCoCrNiMn HEA composite coatings were fabricated by laser cladding, and their microstructure, hardness, and tribological properties were characterized. The results indicate that the coatings are composed of face-centered cubic (FCC) matrix and Cr3C2 phase, and the addition of Cr3C2 enhances the microhardness, with values ranging from 371.1 to 559.2 HV0.5. When paired with Si3N4 ceramic, the average friction coefficient first decreases from 0.77 to 0.59, and then increases to 0.64. When coupled with 440C steel, the average coefficient of friction first decreases from 0.71 to 0.50, and then rises to 0.62. However, the addition of Cr3C2 carbide can significantly improve the wear resistance, and the wear-rate of the coatings paired with Si3N4 ceramic is always much lower than that paired with 440C steel. When paired with 440C steel, the minimum wear-rate of 1.44 × 10−5 mm3/Nm can be achieved. When paired with Si3N4 ceramic, the minimum wear-rate reaches 9.24 × 10−7 mm3/Nm (FeCoCrNiMn/20Cr3C2 coating), which is only 4.91% of the FeCoCrNiMn coating without Cr3C2 reinforcement. The superior wear resistance stems from a cooperative effect of Cr3C2 enhancement and tribo-oxidization. The main wear mechanism against 440C steel is abrasive and adhesive wear, and the main wear mechanism against Si3N4 ceramic shifts from abrasive-adhesive to oxidative wear as the Cr3C2 content increases.