Hydrogen diffusivity and solubility in an Fe-based amorphous metallic alloys

Abstract

Electrochemical hydrogen permeation tests were performed in the Fe 40Ni 38Mo 4B 18 amorphous metallic alloy at temperatures ranging from 313 to 353 K using an elevated cathodic charging electrochemical potential of −2.0 V/SCE in a 0.1N NaOH electrolyte. All permeation curves presented a double sigmoidal shape, suggesting hydride formation. The hydrogen content in the hydrided material was about 100 times greater than the hydrogen solubility in the original amorphous matrix. The effective hydrogen diffusivity in the composite material, partially hydrided, did not vary with temperature, within the experimental errors, while the hydrogen diffusivity in the α (matrix phase), D α, can be expressed as a function of temperature by the relation: D α = 4.2 × 10 −8 exp((−35.5 ± 2.9)/ RT) (m 2 s −1).