High temperature oxidation behavior of a novel cobalt-nickel-base superalloy

Oxidation behavior of a novel cobalt-nickel-base superalloy in air from 600 to 900 degrees Cis investigated in details. The results indicate a two-layer oxide film formed on the surface after oxidation: the external layer of oxide film is mainly composed of Cr2O3 and a few of other oxides, and the inner layer dominantly contains Al2O3. During oxidation at higher temperature and long duration, evaporation of Mo-containing oxide leads to void formation and local failure in external oxide layer, characterized by roughening of oxide film. A formation mechanism of oxide film on this alloy during oxidation is proposed for the first time. (C) 2018 Elsevier B.V. All rights reserved.