The behavior of H was determined by using the gaseous permeation method at 473 to 1073K, under partial pressures of between 0.01 and 0.1MPa:

D (cm2/s) = 6.20 x 10-4 exp[-2.5(kcal/mol)/RT]

The Arrhenius plot of the diffusivity values was linear down to temperatures as low as 473K.

Y.Yamanishi, T.Tanabe, S.Imoto: Transactions of the Japan Institute of Metals, 1983, 24[1], 49-58