| Autor: |
Jebaraj, J. J. M., Morrison, D. J., Suni, l. l. |
| Předmět: |
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| Zdroj: |
Corrosion; Mar2015, Vol. 71 Issue 3, p376-388, 13p |
| Abstrakt: |
We report the hydrogen diffusion coefficients in Alloy 686 (UNS N06686] and Alloy 59 (UNS N06059), using the electrochemical hydrogen permeation method. Optical microscopy and SEM indicate the presence of a second phase inclusion concentrated along the grain boundaries in Alloy 686 specimens, but distributed randomly in Alloy 59 specimens. TEM and X-ray mapping showed the presence of bcc Mo-rich inclusions. Effective diffusion coefficient (Deff) values for hydrogen during successive rise transients reveals the nature of trap sites to be predominantly reversible in Alloy 686, while both reversible and irreversible in Alloy 59. Multiple permeation transients show an increase in diffusion coefficient values for the decay transients (3.88 x 10-11 cm²/s) compared to the rise transients (1.49 x 10-11 cm²/s) in Alloy 686 specimens. The Deff values alternate for each pair of rise and decay transients, which suggests that hydrogen transport is controlled by a high density of reversible trap sites in Alloy 686 specimens. On the other hand, the first rise transient had a lower diffusion coefficient (3.0 x 10-11 cm²/s) compared to successive rise and decay transients (5.0 x 10-11 cm²/s) in Alloy 59 specimens. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Supplemental Index |
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