The rate of H permeation through Cu-Fe composite membranes was measured for incident H molecules and atoms at membrane temperatures of between 570 and 780K. The incident H fluxes ranged from 2.7 x 1022 to 7.3 x 1025/m2s for molecules and from 6 x 1015 to 1.2 x 1019/m2s for atoms. On the basis of diffusion-limited permeation data for molecules, the H permeability of Cu was found to be described approximately by:

P (H/smPa½) = 2 x 1016 exp[-0.64(eV)/kT]

The H recombination coefficients for Cu were deduced from surface-limited molecular H permeation data and from diffusion-limited atomic permeation data. The two methods yielded consistent results. An effective recombination coefficient of about 8 x 10-27H2 m4/H2s was obtained for a Cu surface whose impurity coverage was measured in situ by using Auger electron spectroscopy. This coefficient was essentially independent of temperatures of between 570 and 780K.

Measurement of Hydrogen Permeation through Bilayer Copper–Iron Membranes. A.A.Haasz, P.L.Andrew, A.B.Antoniazzi: Journal of Vacuum Science and Technology A, 1989, 7[3], 1042-6