Wear Properties of Spark Plasma-Sintered AlCoCrFeNi2.1 Eutectic High Entropy Alloy with NbC Additions

AlCoCrFeNi 2.1 - x NbC ( x = 0, 2.5, 7.5, and 10 wt%, denoted as NbC0, NbC2.5, NbC7.5, and NbC10) high-entropy alloy (HEA) matrix composites were fabricated by mechanical alloying (MA) and spark plasma sintering (SPS) methods. The effect of NbC content on the microstructures, Vickers hardness, and wear properties of AlCoCrFeNi 2.1 eutectic high entropy alloy (EHEA) was systematically investigated. The results indicate that the AlCoCrFeNi 2.1 alloy consisted of FCC, B2, Al 2 O 3, and Cr 7 C 3 phases, while the AlCoCrFeNi 2.1 - x NbC ( x > 0) alloys consisted of FCC, NbC, Al 2 O 3, and Cr 7 C 3 phases. The AlCoCrFeNi 2.1 - x NbC alloys exhibit excellent Vickers hardness with 679 HV, 664 HV, 677 HV, and 695 HV, respectively. In addition, with the addition of NbC, the average friction coefficient and wear rate of the AlCoCrFeNi 2.1 - x NbC alloys decrease from 0.59 to 0.42 and from 1.5 × 10 –5 mm 3 N −1 m −1 to 2.4 × 10 –6 mm 3 N −1 m −1 , respectively. Wherein, NbC10 alloy shows the smallest average friction coefficient of 0.42 and lowest wear rate of 2.4 × 10 –6 mm 3 N −1 m −1 , indicating that the NbC10 alloy displays the best wear resistance. And the wear mechanism of the NbC10 alloy was oxidation wear accompanied by slight adhesive wear.