The evolution of H was studied by using a hot-extraction high-vacuum technique which was based upon mass spectrography. The H content of the alloys ranged from 1 to 10ppm[wt]. The H diffusivity in W-3.5Ni-1.5wt%Fe, at temperatures ranging from 510 to 1030C, could de described by:

D (cm2/s) = 0.0057 exp[-10.8(kcal/mol)/RT]

The equivalent data for Ni-23.5Fe-22wt%W, at temperatures ranging from 485 to 1040C, were described by:

D (cm2/s) = 0.011 exp[-10.8(kcal/mol)/RT]

G.L.Powell: Analytical Chemistry, 1972, 44[14], 2357-61