Solid-particle erosion resistance of NbC-reinforced AlCrFeNi medium-entropy alloy at ambient and elevated temperatures

High-entropy alloys (HEAs) and medium-entropy alloys (MEAs) containing passive elements, such as Al and Cr, exhibit good resistance to high-temperature oxidation due to the formation of protective Al 2 O 3 or Cr 2 O 3 oxide scales. The cost-effective AlCrFeNi alloys have demonstrated impressive mechanical properties, attracting considerable attention. In this study, NbC particles in various amounts (10, 20, 30, 40, and 60 wt%) were added to the AlCrFeNi alloy via arc melting to fabricate MEA-matrix composites. The microstructure, mechanical properties, and resistance of the NbC-added AlCrFeNi composites to air-jet sand erosion at both ambient temperature (20 °C) and elevated temperature (500 °C) were investigated. To better evaluate the NbC-AlCrFeNi composites, two commercial materials, high-Cr cast iron (HCCI) and Ni superalloy (Inconel HX), were also tested for comparison. The results demonstrated that the addition of NbC significantly enhanced the erosion resistance of the alloy. Samples containing 40–60 wt% NbC exhibited superior erosion resistance compared to the reference alloys at both 45° and 90° impact angles. The increased hardness, good toughness, and oxidation resistance of the NbC-added AlCrFeNi alloys contributed to their enhanced erosion resistance. This study highlights the potential of AlCrFeNi as a metal matrix for developing high-performance metal-matrix composites (MMCs). • AlCrFeNi medium-entropy alloy (MEA) samples with various NbC contents (10–60 wt%) were synthesized by arc melting. • The NbC addition considerably increased the hardness of the MEA; AlCrFeNi-60 vol%NbC shows the highest hardness about 68 HRC. • AlCrFeNi-NbC samples show higher erosion resistance than the HCCI and Ni-base superalloy at both room temperature and 500 °C. • Erosion at 45° impact angle involves ploughing and cutting; erosion at 90° impact angle involves more craters and platelets. • AlCrFeNi-30%NbC & AlCrFeNi-60%NbC show the highest resistance to 45°-impact erosion and vertical one at 500°C, respectively.