International Hydrogen Conference (IHC 2012): Hydrogen-Materials Interactions
78 Hydrogen Diffusion and Trapping in Random Heterogeneous Materials: Some Advances Using FEM on Polycrystalline Description
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The resistance to environmental degradation, especially Hydrogen Embrittlement (HE) has become a major concern for the durability of materials and structures. Numerous parameters such as the microstructure of the materials play a significant role in HE. In this work, we analyzed the effects of the microstructure and hydrogen trapping on hydrogen diffusion. To do so, we used the FEM software Comsol Multiphysics to simulate electrochemical permeation tests; the membranes are modeled with random microstructures composed of three phases (grains, grain boundaries and triple junctions) with different properties. The macroscopic properties of diffusion depend on the heterogeneous distribution of the phases as well as the trapping sites. The contrast between the properties of the phases (diffusion coefficients and trapping properties) also reveals a significant impact on the macroscopic “apparent” diffusion. Scale effects between the RVE (Representative Volume Element) and the size of the membrane have also been observed, and domains of applicability for standard homogenization methods such as Hashin Shtrikman have been discussed.