Understanding how hydrogen affects the slip and twinning behaviors in metals is paramount for ensuring safe material use in a hydrogen environment and contributing to the development of hydrogen-resistant structural metals. Despite recent reports highlighting an increase in hydrogen-induced twinning in metals under applied deformations, the root case remains elusive. Here, we use molecular dynamics simulations to investigate how high hydrogen concentrations and shear direction affect edge-dislocation behavior in bcc iron. Our findings reveal that the pinning effect increases with hydrogen density along the dislocation line. This effect becomes more pronounced when shear is applied along the twinning direction. We demonstrate the nucleation of micro-twinning, characterized by a three atomic-layer thickness, originating from the dislocation under these conditions. The growth mechanism of this phenomenon aligns with Mahajan's model. Our findings identify the high shear stress as the primary driver for twinning, owing to the hydrogen's strong pinning effect.

中文翻译：

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bcc 铁中氢原子钉扎的刃位错引发孪生：分子动力学研究


了解氢如何影响金属中的滑移和孪生行为对于确保氢环境中材料的安全使用并有助于耐氢结构金属的开发至关重要。尽管最近的报告强调金属在施加变形下氢致孪晶的增加，但根本情况仍然难以捉摸。在这里，我们使用分子动力学模拟来研究高氢浓度和剪切方向如何影响 bcc 铁中的刃位错行为。我们的研究结果表明，钉扎效应随着位错线沿线氢密度的增加而增加。当沿着孪晶方向施加剪切时，这种效应变得更加明显。我们证明了微孪晶的成核，其特征是三原子层厚度，源自这些条件下的位错。这种现象的增长机制与 Mahajan 的模型一致。我们的研究结果表明，由于氢具有很强的钉扎效应，高剪切应力是孪晶的主要驱动因素。