| Summary: | Both crack-free AlCoCrFeNi<sub>2.1</sub> eutectic high-entropy alloy (EHEA) and Y and Hf co-doping AlCoCrFeNi<sub>2.1</sub> EHEA (YHf-EHEA) coatings were prepared by laser cladding. The solidification microstructure, thermal stability, and hot corrosion performance of the coatings at 900 °C under 75% Na<sub>2</sub>SO<sub>4</sub> + 25% NaCl molten salts were investigated. The experimental results showed that the structure of the as-deposited coatings consisted of FCC and BCC/B2 phases. After heat treatment, an Al-rich L1<sub>2</sub> phase was precipitated in the FCC phase of all coatings. The grain sizes of the EHEA and YHf-EHEA coatings after heat treatment at 900 °C for 10 h increased by 27.5% and 15.7%, respectively, compared to the as-deposited coatings. Meanwhile, after hot corrosion, the spallation areas of the YHf-EHEA and EHEA coatings accounted for 14.98% and 5.67% of the total surface area, respectively. In this study, the Y and Hf co-doping did not change the microstructure morphology and phase structure of the coatings but did improve the thermal stability and resistance of the hot corrosion oxide scale spallation, providing a certain amount of data and theoretical support for the application of EHEA coatings as high-temperature protective coatings.
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