Origin of micrometer-scale dislocation motion during hydrogen desorption
Origin of micrometer-scale dislocation motion during hydrogen desorption
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DOI：
10.1126/sciadv.aaz1187
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发表时间：
2020-06
期刊：
影响因子：
13.6
通讯作者：
M. Koyama;S. M. Taheri-Mousavi;Haoxue Yan;Jinwoo Kim;B. Cameron;S. Moeini-Ardakani;Ju Li;C. Tasan
中科院分区：
文献类型：
--
作者：
M. Koyama;S. M. Taheri-Mousavi;Haoxue Yan;Jinwoo Kim;B. Cameron;S. Moeini-Ardakani;Ju Li;C. Tasan
氢在晶界的偏聚导致了微米级的位错运动。氢虽然是一种潜在的能源解决方案，但可以说是高强度金属中最重要的脆化问题。然而，潜在的氢缺陷相互作用导致脆化是具有挑战性的解开。在这里，我们研究了一个有趣的氢效应，以揭示这些相互作用。通过设计无应力条件下样品的原位电子沟道衬度成像实验，我们发现位错（原子尺度的线缺陷）在氢脱附过程中可以移动1.5 μm的距离。结合分子动力学和巨正则蒙特卡罗模拟，我们发现，晶界氢偏析可以引起所需的长程分辨剪切应力，以及短程原子应力波动。因此，在氢的研究中应广泛考虑这种偏析效应。
Hydrogen segregation at grain boundaries induces micrometer-scale dislocation motion. Hydrogen, while being a potential energy solution, creates arguably the most important embrittlement problem in high-strength metals. However, the underlying hydrogen-defect interactions leading to embrittlement are challenging to unravel. Here, we investigate an intriguing hydrogen effect to shed more light on these interactions. By designing an in situ electron channeling contrast imaging experiment of samples under no external stresses, we show that dislocations (atomic-scale line defects) can move distances reaching 1.5 μm during hydrogen desorption. Combining molecular dynamics and grand canonical Monte Carlo simulations, we reveal that grain boundary hydrogen segregation can cause the required long-range resolved shear stresses, as well as short-range atomic stress fluctuations. Thus, such segregation effects should be considered widely in hydrogen research.