Effects of grain-boundary networks on the macroscopic diffusivity of hydrogen in polycrystalline materials
Effects of grain-boundary networks on the macroscopic diffusivity of hydrogen in polycrystalline materials
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DOI：
10.1016/j.commatsci.2014.10.048
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发表时间：
2015-02
影响因子：
3.3
通讯作者：
B. O. Hoch;A. Metsue;J. Bouhattate;X. Feaugas
中科院分区：
文献类型：
--
作者：
B. O. Hoch;A. Metsue;J. Bouhattate;X. Feaugas
晶界的扩散不均匀性影响多晶材料的有效扩散率。然而，两者之间的关系尚未明确确立。在这项工作中，氢的有效扩散率的晶界拓扑结构和连通性的影响进行了研究，膜具有不同的晶粒尺寸。我们在两个维度上模拟了一个多晶体，作为一个包含三相的复合材料，一个用于晶粒，另一个用于晶界。这些阶段的特征在于它们的扩散系数，与不同性质的晶粒边界之间的对比度的六个数量级和晶粒和晶粒边界之间的三个。对高扩散率边界的路径长度和相关长度进行了统计特征。我们发现三种不同的行为的有效扩散系数取决于晶界网络结构。我们观察到两个线性政权之间的连接性参数和有效扩散，和一个非线性政权。我们定量分析了晶界网络结构的有效扩散率的变化的影响，在两个第一制度。
The diffusion heterogeneities of grain boundaries are known to affect the effective diffusivity in polycrystalline materials. However, the correlation between both has not been clearly established. In this work, the influence of the grain boundary topology and connectivity on hydrogen effective diffusivity was investigated, for membranes with different grain sizes. We modeled a polycrystal in two dimensions, as a composite containing three phases, one for the grains and the others for grain boundaries. These phases are characterized by their diffusion coefficient, with a contrast of six orders of magnitude between grain boundaries of different character and three between grains and grain boundaries. The path length and correlation length of high diffusivity boundaries were statistically characterized. We found three different behaviors of the effective diffusivity depending on the grain-boundary networks structure. We observed two linear regimes between the connectivity parameters and the effective diffusivity, and a percolated regime. We quantitatively analyzed the impact of the grain-boundary network structure on the variation of the effective diffusivity, in the two first regimes.