Y-doped AlCoCrFeNi2.1 eutectic high-entropy alloy with excellent oxidation resistance and structure stability at 1000°C and 1100°C

Highlights: • The Y-doped AlCoCrFeNi_2.1 EHEA exhibits superior oxidation resistance and structural stability at high temperatures. • Doping of Y into the Y into the AlCoCrFeNi_2.1 EHEA can significantly improve Al₂O₃ scale adhesion. • The Al-rich β phase with a high aspect ratio is beneficial to facilitate the exclusive formation of Al₂O₃ scale during oxidation at 1000 °C. • The eutectic lamellar structure composed of γ' and β phases is highly stable after prolonged oxidation at 1000 °C and 1100 °C. In this study, the oxidation behavior of AlCoCrFeNi_2.1 eutectic high entropy alloy (EHEA) with/without Y doping at 1000 °C and 1100 °C was reported. The doping of minor Y is crucial to improving the Al₂O₃ scale adhesion and achieving its durability at high temperatures. The oxidation rates of Y-doped AlCoCrFeNi_2.1 EHEA at 1000 °C and 1100 °C are comparable and even lower compared with conventional Al₂O₃-forming NiCoCrAlY/CoNiCrAlY alloys. The superior oxidation resistance and highly stable eutectic lamellar structure after high-temperature oxidation make Y-doped AlCoCrFeNi_2.1 EHEA show a tremendous potential in high-temperature application.