Thermal sprayed high-entropy NiCo0.6Fe0.2Cr1.5SiAlTi0.2 coating with improved mechanical properties and oxidation resistance

In this study, we developed an overlay coating of high-entropy alloy (HEA) NiCo0.6Fe0.2Cr1.5SiAlTi0.2 (C3) via atmospheric plasma spraying. The as-deposited coating is a supersaturated BCC phase except some oxide stringers formed during the spray. However, a plenty of Cr3Si phase forms in the coating and cause a large increase of hardness and wear resistance when aged at 800 and 1100 °C. The oxidation weight gain test demonstrates that the coating exhibits oxidation resistance as good as typical NiCrAlY coating at 1100 °C due to the formation of a dense thermally grown oxide layer (TGO) comprising Al2O3 and Cr2O3. This coating becomes a strong candidate for high-temperature protective layer requiring oxidation and wear resistance.