Influence of annealing on the microstructures and oxidation behaviors of Al8(CoCrFeNi)92, Al15(CoCrFeNi)85, and Al30(CoCrFeNi)70 high-entropy alloys

Abstract

The understanding of the oxidation behaviors of as-cast and annealed high-entropy alloys (HEAs) is currently limited. This work systematically investigates the influence of annealing on the microstructures and oxidation behaviors of AlCoCrFeNi-based HEAs. Annealing was found to alter the distribution of Al-rich phases which caused a change in the oxidation mechanisms. In general, all three of the investigated HEAs displayed some degree of transient oxidation at 1050 °C that was later followed by protective, parabolic oxide growth. The respective oxidation behaviors are discussed relative to existing oxide formation models for Ni-Cr-Al alloys.