Abstract
A potentiostatic pulse technique was used to determine the efficiency of hydrogen entry and trapping in two precipitation-hardened (Inconel 718 and Incoloy 925) and two work-hardened (Inconel 625 and Hastelloy C-276) nickel-base alloys in an acetate buffer (1 M acetic acid/1 M sodium acetate) containing 15 p.p.m. As2O3. The data were examined as a function of charging time and overpotential. The trapping efficiency increases with charging time (f c) and is linearly dependent on (t c)1/2 for sufficiently short times. The range of linearity is determined by the apparent trapping constant for the alloy. The entry efficiency is independent of charging time but it can vary with overpotential depending on the value of the charge transfer coefficient (α) for the hydrogen evolution reaction. In the case of Inconel 718 and Hastelloy C-276, the value of α was 1.4, which is consistent with a mechanism for hydrogen evolution involving fast discharge followed by slow electrochemical desorption.
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Pound, B.G. Potentiostatic pulse technique to determine the efficiency of hydrogen absorption by alloys. J Appl Electrochem 21, 967–972 (1991). https://doi.org/10.1007/BF01077581
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DOI: https://doi.org/10.1007/BF01077581