Verification of the generalised chemical potential for stress-driven hydrogen diffusion in nickel

Abstract

ABSTRACT Hydrogen embrittlement leads to time-dependent failure of structural components. Hydrogen absorption and diffusion contribute to the time dependency and are often treated by thermodynamic diffusion models, which consider the ideal-solution approach and spherical distortion of the lattice. The interaction of spherical lattice distortions with hydrostatic stress fields causes stress-driven hydrogen diffusion. In the present work, ab-initio calculations are used to verify and parametrise the stress dependency of the generalised chemical potential for hydrogen in nickel. Therefore, the partial molar volume for hydrogen in nickel is introduced. The assumption of linear elasticity and a linear dependency on the hydrostatic stress is sufficient to describe hydrogen diffusion on the macroscopic and mesoscopic scale. The work is concluded with hydrogen diffusion simulations, which reveal a minor influence of stress-driven hydrogen diffusion on the overall hydrogen distribution in nickel.