A novel NiCoCrAlPt high-entropy alloy with superb oxidation resistance at 1200 C

A new Y-Hf co-doped NiCoCrAlPt high-entropy alloy (HEA) was developed and subjected to a study on its long-term oxidation behavior at 1200 degrees C. The alloy shows a two-phase eutectic microstructure that comprises a gamma' matrix and beta' martensite precipitates. It is indicated that the alloy has superb oxidation resistance by forming an exclusive, slow-growing Al2O3 scale that remains intact after oxidation at 1200 degrees C for 1000 h. This exceptional performance of the alloy is attributed to the refined microstructure, increased Y/Hf solubility, low oxide growth stress, and a Pt,Al-rich oxide/alloy interface without S segregation. The findings offer scientific insights for the design of Pt-containing oxidation-resistant HEAs.