Effect of Al on oxidation behavior of AlxCrCuFeNi2 (x = 0.2, 0.4, 0.6) high entropy alloys.

The effect of Al on the oxidation behavior of Al x CrCuFeNi 2 (x = 0.2, 0.4, 0.6) high entropy alloys was investigated at 700 °C in water vapor. The oxidation kinetics of all the alloys followed parabolic behavior, with their oxidation rates decreasing with increasing Al concentration. Thick triplex oxide scales with discontinuous Al 2 O 3 formed on the Al 0.2 CrCuFeNi 2 alloy, while a continuous Al 2 O 3 layer and thinner spinel oxide scale grew on Al 0.4 CrCuFeNi 2 and Al 0.6 CrCuFeNi 2 alloys. The early formation of continuous Al 2 O 3 scale in the initial stage of oxidation contributes to the enhanced oxidation resistance of high Al content alloys. ● The steam oxidation kinetics of Co-free Al x CrCuFeNi 2 (x = 0.2, 0.4, 0.6) high entropy alloys decreased with Al concentration increased at 700 °C. ● Al content of Al 0.2 CrCuFeNi 2 (∼4 at% Al) HEA was found to be the boarder-line composition of internal and external Al 2 O 3 formation. ● The early establishment of a continuous Al 2 O 3 scale in initial oxidation contributed to the enhanced oxidation resistance of high Al content HEAs. [ABSTRACT FROM AUTHOR]