Internal oxidation of Fe–2.25Cr has been studied in Fe/FeO Rhines pack (RP) and H2/H2O gas mixtures at 700–900 °C. A novel exposure technique allowing RP experiments in dual atmosphere conditions was developed. No measurable effect of hydrogen on lattice oxygen permeability in ferrite could be detected: neither in single nor in dual atmosphere conditions. The H2/H2O atmosphere was found to induce stronger oxidation attack at alloy grain boundaries resulting in a morphology similar to intergranular stress corrosion cracking often reported in nuclear technology. The intergranular oxidation attack was demonstrated to be independent of the dual atmosphere effect, i.e., hydrogen dissolved in the alloy.

The effect of hydrogen on oxygen permeability has been studied in a diluted Pd–Cr alloy in dual- and single- atmosphere conditions between 600 and 950 °C. The 0.3 mm thick Pd–1.5Cr foil was exposed in dry and humid air as well as in dual-atmosphere conditions, with one sample surface being exposed to air and one to hydrogen, as encountered in solid oxide fuel cells. At all temperatures, Cr oxidized internally forming internal oxidation zones which were measured in metallographic cross sections. Below 800 °C, an external layer of PdO formed on the surface decreasing the internal oxidation kinetics. No measurable effect of hydrogen on the internal oxidation of Cr in Pd has been detected.