Numerical analysis of the influence of scale effects and microstructure on hydrogen diffusion in polycrystalline aggregates

• Published in: Computational materials science Vol. 71; pp. 1 - 9
• Main Authors: Legrand, E., Bouhattate, J., Feaugas, X., Touzain, S., Garmestani, H., Khaleel, M., Li, D.S.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.04.2013; Elsevier
• Subjects: Chemical Sciences; Condensed matter: structure, mechanical and thermal properties; Diffusion; Diffusion in solids; Diffusion of impurities; Exact sciences and technology; Grain boundaries; Hydrogen; Microstructure; Permeation; Physics; Scale effects; Transport properties of condensed matter (nonelectronic); Grain boundaries; Scale effects; Diffusion; Microstructure; Hydrogen; Permeation; Representative volume element; Voronoi tessellation; Scale effect; Polycrystals; Finite element method; Solid clusters; Impurity diffusion; Damage; Hydrogen embrittlement; Concentration distribution
• ISSN: 0927-0256; 1879-0801
• DOI: 10.1016/j.commatsci.2013.01.018

► We simulated permeation tests with hexagonal/random Voronoi microstructures. ► We considered grain boundaries as fast diffusion path only. ► We analysed scale effects with the hexagonal microstructure. ► We compared the hexagonal and random Voronoi microstructures. ► We discussed the effects of the microstructure on hydrogen concentrations. Predicting resistance to environmental degradation, especially hydrogen embrittlement (HE) has become a major concern for life assessment and risk analysis of structural materials. The microstructure of the materials plays a significant role in HE. Despite the large documentation about the subject, the contribution of hydrogen diffusion on this process stays unclear. In this work, we analyze the effects of the microstructure on hydrogen diffusion, especially the influence of grain boundaries considered as high diffusivity paths and possible sites of damage occurrence. Electrochemical permeation was simulated using finite elements method (FEM). Scale effects between the RVE (Representative Volume Element) and the size of the membrane are discussed. Domains of applicability for standard homogenization methods, especially Hashin–Shtrikman model are studied using results from microstructural based FEM. Domains of invariance of diffusion behavior and concentration profiles for grain shapes and the size of the membrane are also analyzed. Thus, the difficulty to extract diffusion properties by permeation test for heterogeneous microstructures is highlighted and discussed.