The temperature dependence of H migration in alloys which contained 0.93, 3.17 or 3.11%Mo, and 0.013, 0.02, or 0.015%C, was examined. The alloys were homogenized in H at 1150C, forged into plates, and cut into sheets. The latter were polished, and annealed at 950C. The diffusivity and permeability were determined by using the stationary-flow technique under isothermal conditions. The data for 300 to 800C showed that H permeation was unaffected by the presence of Mo, whereas the diffusivity was more sensitive to Mo additions. Thus, the activation energy increased from 2.82 to 3.70kcal/g-atom upon increasing the Mo concentration from 0.93 to 3.11% (table 70). This was suggested to indicate that there was a higher bonding energy between H and Mo than between H and Fe.

V.I.Zhitenev, R.A.Ryabov, P.V.Geld: Fizika Metallov i Metallovedenie, 1976, 41[3], 650-2

Table 73

Diffusivity of H in Liquid Fe and Fe-Ni

Table 74

Permeation Parameters for Maraging Steel