Prone H reduction is considered an important factor in the poor corrosion resistance of Mg and its alloys, while the reduced H simultaneously impacts their mechanical properties whose mechanism is still unclear. It can be experimentally found that the elongation of Mg charged with atomic H is 2.76 % greater than that in air. To reveal the underlying physics, multi-scale modeling combining first-principle calculation, molecular dynamic/static (MD/MS) simulation, and crystal plasticity finite element method (CPFEM) is first employed to elaborate the influence of H on Mg at different length scales. The first-principle results show that the Prism-I {100} exhibits the most corrosive nature with an effective H adsorption density that reaches 18 nm and its diffusion barrier is only 0.156 eV . Conversely, the Basal {0001} has the best surficial H resistance. After H infiltration into the Mg matrix, the generalized stacking fault energies of most twining planes decrease by 2.26 % ∼18.49 %. Especially for the Basal {0001}, the H not only lowers its stacking fault energy to -7.13 J , but also impedes its cleavage cracking along [100] according to the MD/MS simulation. The presence of H within the grains induces early initiation of stacking fault and elevates the critical stress at the crack tips. The CPFEM modeling reveals that the difference in twining growth is concentrated within 4 % strain. The H addition promotes the twining of Mg, however, following 4 % strain, the relative activity of planes in the Mg/Mg-H models is consistent.

中文翻译：

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辨别 Mg 中 H 的二元性：H 引起的损伤和延展性


容易发生的H还原被认为是镁及其合金耐蚀性差的重要因素，而还原的H同时影响其力学性能，其机制尚不清楚。实验发现，充有H原子的Mg的伸长率比空气中的伸长率大2.76%。为了揭示底层物理原理，首先采用结合第一性原理计算、分子动态/静态（MD/MS）模拟和晶体塑性有限元法（CPFEM）的多尺度建模来阐述H对不同长度下的Mg的影响秤。第一原理结果表明，Prism-I {100}表现出最强的腐蚀性，有效H吸附密度达到18 nm，扩散势垒仅为0.156 eV。相反，Basal {0001} 具有最佳的表面 H 电阻。当H渗入镁基体后，大多数孪晶面的广义堆垛层错能降低了2.26%~18.49%。特别是对于Basal{0001}，根据MD/MS模拟，H不仅将其堆垛层错能降低至-7.13 J，而且还阻止了其沿[100]的解理裂纹。晶粒中 H 的存在会导致堆垛层错的早期产生，并提高裂纹尖端的临界应力。 CPFEM 模型显示，缠绕生长的差异集中在 4% 应变范围内。 H 的添加促进了 Mg 的缠绕，然而，在 4% 应变之后，Mg/Mg-H 模型中平面的相对活性是一致的。