通过体心立方金属中氢的优先偏聚调制位错反应
Modulating dislocation reactions through preferential hydrogen segregation in bcc metals
AI总结：
本研究通过铁的原子模拟揭示，氢的优先偏聚促进螺位错反应形成稳定的<001>刃位错结，进而演变为空位型位错环，为体心立方金属的氢致损伤提供了新机制。
摘要：
位错之间的相互作用是塑性变形、加工硬化和缺陷积累的基础。尽管大量研究集中在溶质对单个位错的影响上，但溶质如何影响位错-位错反应在很大程度上仍未被探索。在这里，使用铁作为模型体心立方系统的原子模拟，我们证明氢溶质使两个<111>/2螺位错能够反应并形成<001>刃位错结，这一过程在无氢环境中是不利的。这种现象源于氢在<001>位错周围的优先偏聚，它降低了反应产物的能量。生成的<001>位错表现出显著的稳定性，并在应变下转变为<001>空位型位错环。这些空位型位错环可以在连续变形和位错反应过程中积累，作为结构损伤（如开裂和起泡）起始的前兆。我们的发现突出了氢在位错反应中的关键作用，揭示了对解释近期实验观察至关重要的新型缺陷积累机制，并代表了对体心立方金属中氢致损伤理解的重大进展。
英文摘要：
The interaction between dislocations is fundamental to plastic deformation, work hardening, and defect accumulation. While extensive research has focused on the impact of solutes on individual dislocations, how solutes affect dislocation-dislocation reactions remains largely unexplored. Here, using atomistic simulations of iron as a model bcc system, we demonstrate that hydrogen solutes enable two <111>/2 screw dislocations to react and form a <001> edge dislocation junction, a process that is otherwise unfavorable in hydrogen-free environments. This phenomenon arises from the preferential segregation of hydrogen around the <001> dislocation, which reduces the energy of the reaction product. The resulting <001> dislocation demonstrates remarkable stability and transforms into a <001> vacancy-type dislocation loop under strain. These vacancy-type dislocation loops can accumulate during continuous deformation and dislocation reactions, serving as precursors for the initiation of structural damage, such as cracking and blistering. Our findings highlight the pivotal role of hydrogen in dislocation reactions, uncover a novel defect accumulation mechanism crucial for interpreting recent experimental observations, and represent a significant advance in understanding hydrogen-induced damage in bcc metals.
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