The oxidation behavior of a Ni2FeCoCrAl0.5 high-entropy superalloy in O2-containing environments

Abstract

The oxidation behavior of a Ni2FeCoCrAl0.5 high-entropy superalloy was studied at 900 °C in O2-containing environments over the oxygen pressure range of 10 - 1.0 × 105 Pa. The superalloy oxidized parabolically at PO2 < 2.1 × 104 Pa, having its oxidation rates increasing with increasing oxygen pressure. An exclusive α-Al2O3 layer formed on the alloy with its thickness increased with oxygen pressure. On the contrast, a mass-lost kinetics was observed and heterophasic scales of intermixed α-Al2O3, Cr2O3, and M-Cr spinels (M = Ni, Fe, or Co) were detected at PO2 = 1.0 × 105 Pa.