Abstract The embrittlement of metallic materials by hydrogen (H) segregation is widely observed, but not understood well on an atomic scale. In the present study, an atomistic investigation of H embrittlement of various grain boundaries (GBs) has been performed by mapping H segregation energy of trapping sites and examining the effect of H segregation on the decohesion of GBs. The simulation results show that under the equilibrium concentration of H atoms typical of embrittlement in Ni, in conjunction with local H diffusion process, the maximum reduction of tensile strength and fracture energy is 6.60% and 15.75% for Σ5 (210) ⟨100⟩ and Σ17 (530) ⟨100⟩ GBs, respectively. Inspired by experimental observations of the dislocation structures beneath intergranular failure features, further calculations reveal that the embrittling effect of H atoms in metallic materials can be largely facilitated by the boundary disruption and local stress state concentrated on the GB through the plasticity process. The findings directly provide a picture of H embrittlement arising from the cooperative action of H-induced plasticity and GB decohesion.

中文翻译：

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氢致镍晶界脱聚的原子研究

摘要 氢 (H) 偏析引起的金属材料脆化已被广泛观察到，但在原子尺度上并未得到很好的理解。在本研究中，通过绘制捕获位点的 H 偏析能并检查 H 偏析对 GB 脱聚的影响，对各种晶界 (GB) 的 H 脆化进行了原子学研究。模拟结果表明，在Ni典型脆化H原子的平衡浓度下，结合局部H扩散过程，Σ5(210)⟨100⟩和抗拉强度和断裂能的最大降低分别为6.60%和15.75%。分别为 Σ17 (530) ⟨100⟩ GB。受对晶间破坏特征下位错结构的实验观察的启发，进一步的计算表明，通过塑性过程集中在 GB 上的边界破坏和局部应力状态可以在很大程度上促进金属材料中 H 原子的脆化效应。这些发现直接提供了由 H 诱导的可塑性和 GB 脱聚的协同作用引起的 H 脆化的图片。