标题： 钯中空位和晶界处氢的偏析基础研究 显示英文标题

标题： Fundamental Study of Hydrogen Segregation at Vacancy and Grain Boundary in Palladium

摘要： 我们使用密度泛函理论研究了钯晶体中氢在间隙、空位和晶界处的基本结合过程。 结果显示，氢倾向于占据钯基体中的八面体间隙位点，然而一个稳定的氢-空位复合物最多可以包含八个氢原子围绕空位的四面体位点。 此外，氢的存在有助于附近空位的配对或形成，这与实验和理论研究之前的建议一致。 此外，这一观察结果可能意味着通过微孔和裂纹的连接而产生的氢脆（HE）机制。 然而，氢在晶界处的偏析表现出不同的效果。 高浓度的氢导致晶界扩展，这与实验中观察到的晶界脱粘的氢脆机制有关。 显示英文摘要

摘要： We have studied the fundamental process of hydrogen binding at interstitial, vacancy and grain boundary (GB) in palladium crystals using Density-Functional Theory. It showed that hydrogen prefers to occupy the octahedral interstitial site in Pd matrix, however a stable H-vacancy complex with most H occupations would contain up to eight hydrogen atoms surrounding the vacancy at tetrahedral sites. Furthermore, H presence assists the pairing or formation of nearby vacancies, which in agreement with previous suggestions by both experiment and theory investigation. Also, this observation could imply about a hydrogen embrittlement (HE) mechanism through the connections of microvoid and cracks. The segregation of hydrogen at grain boundary, nevertheless, has shown a different effect. High H accumulation results in grain boundary extension, which is related the HE mechanism of grain decohesion observed by experiments.