The migration of the isotopes through the α-phase was studied, by using the pressure-modulation technique, at temperatures of between 500 and 1000K. Ion bombardment was used to extend the temperature range of the experiments. The diffusion results could be described by:

D:     D (m2/s) = 4.28 x 10-8 exp[-6.47(kJ/mol)/RT]

H:     D (m2/s) = 4.43 x 10-8 exp[-5.31(kJ/mol)/RT]

and the permeation results could be described by:

D:     P (mol/m s MPa½) = 1.05 x 10-5 exp[-32.4(kJ/mol)/RT]

H:     P (mol/m s MPa½) = 1.77 x 10-5 exp[-31.6(kJ/mol)/RT]

It was found that the ratio of H diffusivity to D diffusivity depended upon the temperature, and approached unity with increasing temperature.

Measurements of Permeation of Hydrogen Isotopes through α-Iron by Pressure Modulation and Ion Bombarding. A.Tahara, Y.Hayashi: Transactions of the Japan Institute of Metals, 1985, 26[12], 869-75

Table 39

Diffusivity of H in Fe at 21C under Hydrostatic Pressure