Liu Wusong, Miao Naihua, Zhu Linggang, Zhou Jian, Sun Zhimei
School of Materials Science and Engineering, Beihang University, Beijing 100191, China.
Phys Chem Chem Phys. 2017 Dec 13;19(48):32404-32411. doi: 10.1039/c7cp07208b.
Hydrogen and oxygen play an important role in the hydrogen embrittlement and oxidation of novel Co-based alloys with γ/γ' microstructure. In this study, the adsorption of hydrogen and oxygen atoms on the FCC-Co(111) surface and their diffusion behavior from the surface into the sub-layers and bulk have been investigated by means of first-principles calculations. It is observed that hydrogen and oxygen atoms prefer to adsorb on the fcc and hcp (threefold hollow) sites, respectively. The hydrogen atom can penetrate into the first and second sub-layers energetically, while it is not feasible for the oxygen atom as diffusion from the surface into the first sub-layer is more difficult. It is found that the calculated diffusion coefficients of hydrogen are in good agreement with the available experimental data. Finally, we briefly discuss the changes in total magnetic moment along the Oct-Tet-Oct diffusion path and the associated electronic structures. The present work is helpful to provide comprehensive guidance for the development and applications of novel Co-based alloys.
氢和氧在具有γ/γ'微观结构的新型钴基合金的氢脆化和氧化过程中起着重要作用。在本研究中，通过第一性原理计算研究了氢原子和氧原子在FCC-Co(111)表面的吸附及其从表面扩散到亚层和体相中的行为。观察到氢原子和氧原子分别倾向于吸附在面心立方（fcc）和六方密堆积（hcp，三重中空）位点上。氢原子能够以能量有利的方式渗透到第一和第二亚层，而氧原子则不行，因为从表面扩散到第一亚层更加困难。结果发现，计算得到的氢扩散系数与现有的实验数据吻合良好。最后，我们简要讨论了沿着八面体-四面体-八面体扩散路径的总磁矩变化以及相关的电子结构。本工作有助于为新型钴基合金的开发和应用提供全面的指导。
