Influence of Co to Ni ratio in γ'-strengthened model alloys on oxidation resistance and the efficacy of the halogen effect at 900 °C

S. Virtanen, M. Weiser, H.-E. Zschau, M. Göken, M.C. Galetz, C. Zenk, S. Neumeier

Corrosion Science (2019), DOI: 10.1016/j.corsci.2019.05.007

The role of base element (Co or Ni) in γ′-strengthened single-crystalline superalloys was elucidated in the present study. Reaction kinetics during oxidation at 900°C were assessed by thermogravimetry and measurements of individual layer thicknesses in the multilayered oxide scales. The development of diffusion-limiting barrier layers as well as the extent of sub-scale phase transitions could be directly correlated to the Co/Ni ratio in the alloy. For the first time a surface pretreatment with F was applied to Co-base superalloys. Apparent differences in the efficacy of the halogen effect depending on the Co content in the model alloys were observed.

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