By measuring out-diffusion from samples which had previously been loaded with H, the H diffusion coefficients in binary alloys were determined. They were found for the α-phase of each alloy, for temperatures of between 25 and 300C, and could be described by:log[D] = -3.512 + 0.024Ni - (1651 + 112Ni)/4.575T(K)
when the contents of the alloying elements were expressed in mol%. The additions decreased the H diffusion coefficient. The diffusion-retarding effect of the alloying element increased with decreasing temperature. The overall temperature expression for diffusion of H in Fe:
log[D] = -3.67 - 1438/4.575T
was obtained by extrapolating the above equation to 0% alloying element concentration. This result agreed quite well with the most likely value for the lattice diffusion of H; as extrapolated from measurements made at high temperatures.
H.J.Koenig, K.W.Lange: Archiv für Eisenhüttenwesen, 1975, 46[10], 669-75
Table 138
Diffusivity of H in Liquid Fe and Fe-Ni
Ni (wt%) | Temperature (C) | D (cm2/s) |
0 | 1560 | 7.5 x 10-4 |
0 | 1580 | 8.0 x 10-4 |
10 | 1530 | 1.23 x 10-3 |
10 | 1560 | 1.35 x 10-3 |
10 | 1580 | 1.46 x 10-3 |
20 | 1500 | 2.22 x 10-3 |
20 | 1530 | 2.30 x 10-3 |
20 | 1560 | 2.45 x 10-3 |
20 | 1580 | 2.61 x 10-3 |