Hydrogen diffusion and trapping in nickel-based alloy 625: An electrochemical permeation study. (20th July 2022)

• Record Type: Journal Article
• Authors: Lu, Xu; Wang, Dong; Johnsen, Roy
• Is Part Of: Electrochimica acta. Volume 421(2022)
• Publication Date: 2022-07-20
• Subjects: Nickel-based alloy 625 -- Hydrogen -- Diffusion -- Trapping -- Hydrogen fugacity; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2022.140477
• Languages: English
• ISSNs: 0013-4686

Abstract

Highlights: Based on the electrochemical permeation test, a sinusoidal trend in D e f f was observed when the cathodic charging current density varies from -1 to -100 mA/cm 2 . The expressions for the hydrogen fugacity on the surface associated with hydrogen evolution reactions during the change of applied cathodic current density was deduced. The energy associated with the solubility energy of lattice hydrogen and reversible trapping site was determined as 9.90 kJ/mol and 26.04 kJ/mol, respectively. Abstract: This work studied the effect of cathodic charging conditions on hydrogen diffusion and trapping behavior in a nickel-based Alloy 625 using the electrochemical permeation approach. Results showed that the effective diffusion coefficient of hydrogen can be expressed as D e f f = 1.82 × 10 − 7 exp ( − 44.46 k J m o l R T ) m 2 / s . A sinusoidal trend in D e f f with charging current density was observed showing a deflection point at -40 mA/cm 2, which contributes to the most efficient hydrogen permeation. In addition, the thermodynamic relationship between hydrogen activity and electrochemical potential was investigated. Furthermore, the energy associated with the solubility energy of interstitial hydrogen and reversible trapping site was determined as 9.90 kJ/mol and 26.04 kJ/mol, respectively.