The time-lag permeation method was used to determine the diffusivity of H at temperatures ranging from 496 to 946C. Previous measurements had indicated a large positive deviation from Arrhenius behavior at temperatures above 600C. No such deviation was found in the present measurements; which were also in good accord with previous determinations that had been made at lower temperatures. The diffusivity at temperatures ranging from 469 to 946C could be described by:

D (m2/s) = 2.83 x 10-7 exp[-21.7(kJ/mol)/RT]

K.Katsuta, R.J.Farraro, R.B.McLellan: Acta Metallurgica, 1979, 27[7], 1111-4