High-Temperature Oxidation Behaviours of AlCoCrFeNi High-Entropy Alloy at 1073-1273 K

The effect of the temperature on the characteristics of the oxide films on AlCoCrFeNi high-entropy alloy (HEA) at 1073-1273 K was investigated through scanning electron microscopy, energy-dispersive spectroscopy, and x-ray diffraction. Elemental enrichments in the outer oxide layer and internal oxide zone were studied. The oxidation resistance of AlCoCrFeNi HEA was compared with two commercial alloys [825 Ni-based alloy and 2205 duplex stainless steel (DSS)] with similar Cr content at 1273 K. These alloys are ranked as follows in descending order of oxidation resistance at 1273 K: AlCoCrFeNi HEA, 825 Ni-based alloy, and 2205 DSS. At 1273 K, both Cr and Mo were enriched in the outer oxide layer on 825 Ni-based alloy and 2205 DSS. Only Cr enrichment was observed on the AlCoCrFeNi HEA, but the Cr content in the outer oxide layer on the HEA was greater than those on the 825 Ni-based alloy and 2205 DSS. This might be the main reason why the AlCoCrFeNi HEA showed the best oxidation resistance among the three studied alloys.