Abstract:Tribological properties of Al19Fe20-xCo20-xNi41Mo2x (x=0, 1, 2, 3, 4, 5) eutectic high-entropy alloys (EHEAs) were investigated in this research. Results show that EHEAs with trace Mo addition can form the face-centered cubic (fcc)+B2 eutectic microstructure, whereas EHEAs with relatively higher Mo content can form fcc+B2+μ dendritic microstructure. Mo element is beneficial to the strength enhancement of L12 phase and the ductility improvement of B2 phase. However, with increasing the Mo content to x>2, the resultant Mo-rich μ phase degrades the strength and plasticity of EHEAs. Al19Fe18Co18Ni41Mo4 EHEA has the optimal combination of high strength and high ductility. Increasing Mo content can improve the oxidation resistance of EHEAs. With increasing the Mo content, EHEA forms a tribo-oxide layer with improved oxidation resistance during sliding process, and the friction coefficient is monotonically decreased. This research provides guidance for the investigation of tribological properties of Al19Fe20-xCo20-xNi41Mo2x EHEAs.