Abstract The presence of interstitial hydrogen in steel produces embrittlement, which poses a severe risk to the integrity of structural components. Although real steel, as a multi-phase material with crystal defects at several scales is too complex a system to be modelled utilizing ab-initio calculations, mechanisms of hydrogen (H) diffusion in metals have attracted interest and have been widely described in the literature. Here, we study from first-principles (DFT code CASTEP) the role of phonons on the diffusion of hydrogen at different temperatures in a bcc iron lattice (Fe16H) via a calculation of Helmholtz’s free energy, which has been fed into COMSOL for finite element calculations. The diffusion coefficient of hydrogen between 250 K and 700 K was obtained and, the increment in the diffusion barrier at the higher temperatures, traditionally attributed to a transition regime, is now explained by the contribution of phonons. The effect of different traps sites on hydrogen diffusion is studied by using the FEM model.

中文翻译：

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不同温度下氢在碳钢中的扩散和捕集

摘要 钢中间隙氢的存在会产生脆化，这对结构部件的完整性构成严重威胁。虽然真正的钢，作为一种多相材料，在几个尺度上具有晶体缺陷是一个过于复杂的系统，无法利用 ab-initio 计算进行建模，但金属中的氢 (H) 扩散机制引起了人们的兴趣，并在文献中得到了广泛的描述。 . 在这里，我们通过计算亥姆霍兹自由能，从第一性原理（DFT 代码 CASTEP）研究声子在不同温度下氢在体心立方铁晶格 (Fe16H) 中扩散的作用，该自由能已输入 COMSOL 进行有限元计算。获得了 250 K 和 700 K 之间的氢扩散系数，并且在较高温度下扩散势垒的增加，传统上归因于过渡机制，现在由声子的贡献来解释。利用有限元模型研究了不同陷阱位点对氢扩散的影响。