Cu, Cu-Al-Fe, Cu-Be, Cu-Si, Cu-Si-Mn, Cu-Sn-P: H Diffusion and Permeation

A study was made of the permeation and diffusion of H in various Cu-based alloys (tables 19 and 20). The pre-exponential factors were found to depend strongly upon the alloying elements which were present. When 2%Be was present, the permeability decreased by a factor of 3. The addition of 3%Si caused a factor of 6 change, and additions of 9%Al and 4%Fe caused a factor of 100 change. The effect of the alloying elements could be qualitatively related to the thermodynamic stability of their oxides and to the uniformity of the oxide layers which formed on the surface. It was suggested that the decrease in permeability was due not only to a lower mobility of H in the alloy lattice, but also to a lower solubility and to the formation of surface oxide layers.

J.I.Belyakov, J.I.Zvezdin: Uch. Zap. Leningrad (Gos. Univ. Ser. Fiz. Nauk), 1968, 345, 44-9

Table 19

Parameters for H Diffusion in Cu Alloys at 800 to 1000K

Alloy	Do (cm2/s)	E (kcal/g-atom)
Cu (commercially pure)	2.29 x 10-2	11.3
Cu (oxidized and reduced)	2.51 x 10-2	11.3
Cu-7Sn-0.2%P	3.2 x 10-3	9.2

Table 20

Parameters for H Permeation in Cu Alloys at 800 to 1000K

Alloy	Po (cm2/s atm½)	E (kcal/g-atom)
Cu (commercially pure)	0.119	20.0
Cu (oxidized and reduced)	0.134	20.0
Cu-7Sn-0.2%P	0.011	16.7
Cu-3Si-1%Mn	0.009	18.8
Cu-2%Be	0.021	18.8
Cu-9Al-4%Fe	0.001	20.1
Cu-1.5%Si	0.029	18.3
Cu-3.0%Si	0.011	18.3