Partitioning of Interstitial Segregants during Decohesion: A DFT Case Study of the Σ3 Symmetric Tilt Grain Boundary in Ferritic Steel
Partitioning of Interstitial Segregants during Decohesion: A DFT Case Study of the Σ3 Symmetric Tilt Grain Boundary in Ferritic Steel
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DOI：
10.3390/ma12182971
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发表时间：
2019-09-01
期刊：
影响因子：
3.4
通讯作者：
Janisch, Rebecca
中科院分区：
文献类型：
--
作者：
Huang, Xiang;Janisch, Rebecca
氢原子在金属晶界上的作用通常对界面的结合力是有害的。这种效果可以量化的强化能量，这是获得以下的Rice和Wang的热力学模型。该模型的一个关键组成部分是原子与消粘过程中产生的自由表面的结合能或溶解能。在多组分系统的晶界处，不同的物质如何在解理的自由表面上分配和分布并不立即清楚。在这项工作中，它表明，分配模式的选择有显着的影响，H和C晶界内聚力的预测影响。为此，研究了具有不同间隙C和H含量的bcc Fe中σ 3（112）[1（1）over bar 0]对称倾斜晶界，考虑了元素的所有可能分布以及表面扩散效应。H作为单一元素对晶界结合力有负面影响，与H分布的细节无关。另一方面，C可以双向作用，增强或降低界面的内聚性。混合H和C成分的效果取决于分配模式。然而，总的趋势是有害情况的数量随着H含量的增加而增加。分解的强化能量到化学和机械的贡献表明，在高C含量的弹性贡献占主导地位，而化学贡献设置的趋势高H含量。
The effect of hydrogen atoms at grain boundaries in metals is usually detrimental to the cohesion of the interface. This effect can be quantified in terms of the strengthening energy, which is obtained following the thermodynamic model of Rice and Wang. A critical component of this model is the bonding or solution energy of the atoms to the free surfaces that are created during decohesion. At a grain boundary in a multicomponent system, it is not immediately clear how the different species would partition and distribute on the cleaved free surfaces. In this work, it is demonstrated that the choice of partitioning pattern has a significant effect on the predicted influence of H and C on grain boundary cohesion. To this end, the Sigma 3(112)[1 (1) over bar0] symmetric tilt grain boundary in bcc Fe with different contents of interstitial C and H was studied, taking into account all possible distributions of the elements, as well as surface diffusion effects. H as a single element has a negative influence on grain boundary cohesion, independent of the details of the H distribution. C, on the other hand, can act both ways, enhancing or reducing the cohesion of the interface. The effect of mixed H and C compositions depends on the partition pattern. However, the general trend is that the number of detrimental cases increases with increasing H content. A decomposition of the strengthening energy into chemical and mechanical contributions shows that the elastic contribution dominates at high C contents, while the chemical contribution sets the trend for high H contents.