A 1mm substrate of 3N5-purity Fe was prepared by cold-rolling, and was coated with 3N-purity vacuum-deposited films of the other metals. The permeation of H through the composite films was then measured by using electrochemical techniques. It was found that the diffusivity of H appeared to be reduced in thin films. It was suggested that this was caused by the effect of H trapping by vacancies, which increased with decreasing thickness, or by the formation of an intermediate layer.

N.Takano, Y.Murakami, F.Terasaki: Scripta Metallurgica et Materialia, 1995, 32[3], 401-6