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] = -3.625 - 0.032Mn - (1491 + 23Mn)/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 the diffusion of H in Fe:

log[D] = -3.67 - 1438/4.575T

was obtained by extrapolating the above equations 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 116

Lattice Diffusion Parameters for 22P in Fe-Mn

 

P (at%)

Mn (at%)

Phase

Do (m2/s)

E (kJ/mol)

-

-

paramagnetic

2.87 x 10-2

271

-

-

ferromagnetic

1.38 x 101

332

0.16

-

paramagnetic

3.76 x 10-2

275

0.16

-

ferromagnetic

1.08 x 10-1

288

0.18

-

paramagnetic

2.55 x 10-3

247

0.18

-

ferromagnetic

1.06 x 103

359

0.38

-

paramagnetic

8.87 x 10-3

259

0.38

-

ferromagnetic

4.90 x 100

316

0.17

0.38

paramagnetic

7.93 x 10-8

159

0.17

0.38

ferromagnetic

2.35 x 10-1

292

0.11

2.11

paramagnetic

6.56 x 10-5

211

0.11

2.11

ferromagnetic

1.32 x 10-2

259