Samples of amorphous Fe40Ni38Mo4B18 alloy were submitted to electrochemical H permeation tests, under cathodic charging conditions, which resulted in high H fugacity. It was observed that the apparent H diffusivity was dependent upon the H concentration used. For cathodic charging levels of -1.15 and -1.35V (standard calomel electrode), the H permeation curves exhibited a single sigmoidal shape; typical of tests where no hydride formation occurred. For higher applied cathodic potentials (-1.65, -1.80 and -2.00V), strong deviations were observed from the theoretical curve shape. This suggested the formation of a hydride phase across the thickness of the alloy. The value of the apparent H diffusion coefficient in the β-phase hydride, formed in the amorphous Fe40Ni38Mo4B18 alloy, was found to be equal to 6.0 x 10-15m2/s at an applied cathodic potential of -2.00V at 40C.

Hydrogen Diffusivity in Fe40Ni38Mo4B18 Amorphous Metallic Alloys. D.S.dos Santos, P.E.V.de Miranda: Journal of Alloys and Compounds, 2003, 348[1-2], 241-6