Surface barrier for hydrogen permeability in Ni3Al — influence of Cr, Fe and Zr

Hydrogen permeability through Ni3Al–M intermetallic membranes was studied by gas-permeation method in the temperature range 573–1223 K. The influence of the third element (M=Cr, Fe and Zr) upon the retardation of hydrogen transfer from the gas phase into the bulk was qualified by dependence of measured permeation flux J through the sample on sample thickness d. It was found that Zr supports and, on the contrary, Cr eliminates the inhibiting effect of the surface. The most expressive effect of Fe additions consists in a considerably raised grain boundary brittleness in a hydrogen environment.