Oxidation of Superalloys in Impure Helium

Abstract

An investigation was made to clarify the corrosion of several superalloys in impure helium.
The corrosion in helium was more severe than in air. This corrosion was due to the insufficiency in supply of oxidizing species to form a continuous protective scale. For this reason, the severe corrosion occured with the formation of Cr-denuded zone and with internal oxidation.
This oxidation could be reduced by the surface treatment, such as calorizing and pre-oxidizing in air to form a protective film on the surface.