Large-grained (4mm) specimens of 4N5-purity material were charged with high-purity H by heating (600C, 48h). The diffusion coefficients were deduced from desorption measurements. The diffusivity at temperatures of between 450 and 625C (table 20) could be described by:

D (m2/s) = 1.01 x 10-5 exp[-47.7(kJ/mol)/RT]

R.A.Outlaw, D.T.Peterson, F.A.Schmidt: Scripta Metallurgica, 1982, 16[3], 287-92