High-temperature oxidation behavior of carbon doped CoCrNi medium entropy alloy fabricated by laser powder bed fusion

The oxidation behaviour of two CoCrNi medium entropy alloys with carbon contents of 0.25 at% and 0.75 at% (0.25C MEA and 0.75C MEA) was investigated. These alloys were designed via laser powder bed fusion (L-PBF) to enhance mechanical properties by controlling in-situ nano precipitates. High-temperature oxidation tests were conducted at 900, 1000, and 1100 °C for 24 h in an air-like atmosphere. The 0.25C MEA exhibited weight changes of 0.052–0.852 mg/cm 2 , while the 0.75C MEA showed higher changes of 0.256–1.148 mg/cm 2 , highlighting the significant impact of carbon on oxidation resistance. Carbide formation was suggested to play an important role in determining internal oxidation behaviour.