Combinatorial synthesis and analysis of AlxTayVz-Cr20Mo20Nb20Ti20Zr10 and Al10CrMoxNbTiZr10 refractory high-entropy alloys: Oxidation behavior

The combinatorial development of refractory high-entropy alloy AlxTayVz-Cr20Mo20Nb20Ti20Zr10 (AlxTayVz-Q) was carried out, and microstructural analysis was performed. The homogenized AlxTayVz-Q revealed a body-centered cubic structure with intermetallic phases. High-temperature oxidation analysis of AlxTayVz-Q for 1 h at 1000 °C using thermogravimetric analysis (TGA) revealed volatile oxidation of the alloy. Therefore, in an effort to improve the oxidation resistance of the alloy, the composition was modified to Al10CrMoxNbTiZr10 and analyzed. The TGA analysis revealed enhanced oxidation resistance of Al10CrNbTiZr10 (Mo-0), and a weight gain of only 1 mg/cm2 after oxidation for 1 h at 1000 °C in air, owing to the formation of the protective oxides of Al and Cr. The Mo-x samples were subjected to prolonged oxidation (for 50 h) at 1000 °C in air. After 50 h of oxidation, the Mo-0 sample showed a weight gain of ∼24 mg/cm2 and remained intact. The energy dispersive spectroscopy analysis of the oxide scale formed after 50 h of oxidation revealed CrNbO4, Al2O3, and AlTiO5, which account for the enhanced oxidation resistance of Mo-0 and forecasts its potential for high-temperature applications.