Influence of Cr upon hydrogen permeation in Ni3Al at low partial pressure of oxygen

Permeability Φ of hydrogen with low partial pressure of O2 in Ni3Al, Ni3AI–4Cr, Ni3Al–8Cr intermetallics and in related disordered solid solutions Ni–4Cr, Ni–8Cr, Ni–7Al, Ni–7A1–8Cr (compositions in at. %) was measured in the temperature range 523–1223 K by gas permeation method. A maximum of Φ at about 623 K observed in Ni3A1 is most likely due to maximum of hydrogen solubility reported in literature. It was observed that the addition of Cr to Ni3Al reduces the Φ. Chromium shows the destabilizing effect that reduces the protective function of Al-based oxides. Aluminum, present in the studied alloys, is responsible for a surface protective layer that reduces the permeation flux of hydrogen.