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 degrees C. The oxidation weight gain test demonstrates that the coating exhibits oxidation resistance as good as typical NiCrAlY coating at 1100 degrees 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.