Y2O3-Doped Fe-Mn-Ni-Cr Medium Entropy Alloy with Superior Oxidation and Spallation Resistance Fabricated by Spark Plasma Sintering

We report a type of superior oxidation and spallation-resistant Y2O3-doped Fe-Mn-Cr-Ni medium-entropy alloy (MEA) fabricated by spark plasma sintering. A continuous weight-gain oxidation experiment was designed to study the oxidation kinetics of undoped Fe-Mn-Cr-Ni MEA and Y2O3-doped Fe-Mn-Cr-Ni MEA. The microstructures of oxide scale and the potential oxidation mechanisms are discussed. The results indicate that the oxidation and spallation resistance of Fe-Mn-Cr-Ni MEA can be enhanced through Y2O3 doping. The two MEAs follow the single-stage parabolic law at temperatures ranging from 700 degrees C to 900 degrees C. Y2O3-doped MEA exhibits a lower oxidation rate, characterized by oxidation rate constant of 0.025 mg(2) cm(-4) min(-1), which is 86.8% lower than that of Y2O3-free MEA at 900 degrees C. The oxidation activation energy of Y2O3-doped MEA is 135.3 kJ/mol, which is 30.5% higher than that of Y2O3-free MEA. The Y2O3-doped MEA demonstrates much better resistance to the oxide scale spallation compared with the Y2O3-free MEA, resulting from the good suppression of interface rumpling.