Mesoscale modeling of diffusion in polycrystalline structures

Bassman, Lori; Ibrahim, Nabeel Robert; Pinsky, Peter M.; Saraswat, Krishna C.; Deal, Michael D.

doi:10.1109/sispad.1997.621359

Cited by 5 publications

(3 citation statements)

References 4 publications

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“…Many reports consider models with square grains surrounded by GB [12,15,19,34]. Very often, they consider that the concentration within GB width is constant and unchanging.…”

Section: Kinetic Modelmentioning

confidence: 99%

Kinetic Modeling of Grain Boundary Diffusion: The Influence of Grain Size and Surface Processes

Jaseliūnaitė

Galdikas

2020

Materials

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Based on rate equations, the kinetics of atom adsorption, desorption, and diffusion in polycrystalline materials is analyzed in order to understand the influence of grain boundaries and grain size. The boundary conditions of the proposed model correspond with the real situation in the electrolytes of solid oxide hydrogen fuel cells (SOFC). The role of the ratio of grain boundary and grain diffusion coefficients in perpendicular and parallel (to the surface) concentration profiles is investigated. In order to show the influence of absolute values of grain and grain boundary diffusion coefficients, we select four different cases in which one of the diffusion coefficients is kept constant while the others vary. The influence of grain size on diffusion processes is investigated using different geometrical models. The impact of kinetic processes taking place on the surface is analyzed by comparing results obtained assuming the first layer as a constant source and then involving in the model the processes of adsorption and desorption. It is shown that surface processes have a significant influence on the depth distribution of diffusing atoms and cannot be ignored. The analytical function of overall concentration dependence on grain and grain boundary volume ratio (Vg/Vgb) is found. The solution suggests that the concentration increases as a complementary error function while Vg/Vgb decreases.

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“…Many reports consider models with square grains surrounded by GB [12,15,19,34]. Very often, they consider that the concentration within GB width is constant and unchanging.…”

Section: Kinetic Modelmentioning

confidence: 99%

Kinetic Modeling of Grain Boundary Diffusion: The Influence of Grain Size and Surface Processes

Jaseliūnaitė

Galdikas

2020

Materials

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“…There are several models to compute the effective diffusivity of a heterogeneous material as a function of its grain size [11] [12] [13]. Hart's model [14] considers parallel grain boundaries oriented in the diffusion direction.…”

Section: Introductionmentioning

confidence: 99%

Modeling the Nitrogen Diffusion Enhancement Resulting from a NanoPeening® Treatment on a Pure Iron – Influence of the Grain Morphology

Lacaille¹,

Kermouche²,

Tumbajoy-Spinel³

et al. 2015

DDF

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It is well known that nanocrystalline materials have enhanced diffusion properties due to their high grain boundary density which act as fast diffusion channels compared to the lattice. In this paper, we aim at simulating the nitriding process of a pure iron nanostructured by NanoPeening® process. We use a simple diffusional approach taking into account the grain size and the grain morphology resulting from the NanoPeening® treatment. EBSD measurements are carried out to extract morphological parameters which are used in the homogenization method to extract the effective diffusivity distribution. Then a 1D diffusion simulation is performed with this distribution and shows that the grain morphology resulting from the NanoPeening® treatment does not deteriorate the diffusion properties of the material but in fact, improves the nitrogen penetration depth and the diffusion kinetics in addition to the effect of the grain size reduction.

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“…Also, some authors studied the grain boundary diffusion effect on the effective diffusivity with numerical methods. Gryaznov et al [20] and Bassman et al [21] have made a finite element analysis considering two different media: grains and grain boundaries. This type of methodology has also been applied with the finite difference method [22] or by computation of the effective conductivity of two dimensional disordered random Voronoi networks [23] with Kirchhoff equations resolved by Lanczos algorithm [24].…”

Section: Introductionmentioning

confidence: 99%

Finite element analysis of the grain size effect on diffusion in polycrystalline materials

Lacaille

Morel²,

Feulvarch

et al. 2014

Computational Materials Science

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International audiencePolycrystalline materials with refined grain size are well known to have enhanced diffusion properties compared to coarse grain materials. Due to their high grain boundary density, the macroscopic diffusivity of such materials is increased. Indeed, grain boundaries are fast diffusion channels in the material. In this paper, a numerical method to calculate the diffusivity of polycrystalline materials as a function of their grain size is proposed. A homogenization technique is applied on polycrystalline representative volume elements on which diffusion calculations are performed with a finite element method. This technique allows to extract the effective diffusivity of the material for different grain sizes. A relationship is then built between the diffusivity and the grain size. It is shown that the extracted diffusivity follows a mixture law of both diffusivities in the grains and grain boundaries, as proposed by Hart [14], but taking into account grain boundaries randomly oriented compared to the diffusion direction

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Mesoscale modeling of diffusion in polycrystalline structures

Cited by 5 publications

References 4 publications

Kinetic Modeling of Grain Boundary Diffusion: The Influence of Grain Size and Surface Processes

Kinetic Modeling of Grain Boundary Diffusion: The Influence of Grain Size and Surface Processes

Modeling the Nitrogen Diffusion Enhancement Resulting from a NanoPeening® Treatment on a Pure Iron – Influence of the Grain Morphology

Finite element analysis of the grain size effect on diffusion in polycrystalline materials

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