The diffusion of H in 5N-purity polycrystalline material was investigated by using isothermal and constant heating-rate desorption techniques. The latter technique was used to clarify the effects of microstructural trap states upon the apparent diffusivity. The isothermal desorption of H from annealed uniformly-charged cylindrical specimens was controlled by bulk diffusion. The data at 30 to 600C obeyed:

D (cm2/s) = 1.75 x 10-4 exp[-3.9(kcal/mol)/RT]

The constant heating-rate desorption spectra revealed 3 distinct trapping states, with desorption energies of 15.3, 43.5 and 84.8kJ/mol. These trapping states were associated with interstitial lattice sites, dislocations and vacancies, respectively.

G.A.Young, J.R.Scully: Acta Materialia, 1998, 46[18], 6337-49

The best linear fits to the solute diffusion data ([562] to [565], [567] to [570], [573] to [577], [581] to [585], [592] to [599], [608] to [611], [623] to [626]) yield:

Au: Ln[Do] = 0.67E – 20.7 (R2 = 0.999); Co: Ln[Do] = 0.43E – 12 (R2 = 0.69);

Cu: Ln[Do] = 0.69E – 22.7 (R2 = 0.99); Fe: Ln[Do] = 0.56E – 20.5 (R2 = 0.996);

H: Ln[Do] = 0.63E – 9.45 (R2 = 0.96); Mn: Ln[Do] = 0.52E – 21.4 (R2 = 0.993);

Zn: Ln[Do] = 0.77E – 24 (R2 = 0.99)