报告题目：Unified charge transfer associated strain destabilization mechanism of hydrogen clusters around metal vacancies and its application to DOS steels

报告内容简介：Interaction between hydrogen and lattice defects underlies diverse materials phenomena, including H storage, H embrittlement, metallic H membranes, nuclear fusion reactors, etc. Crucial to all these problems is trapping of H at the lattice defects, such as vacancies, voids, dislocations, grain boundaries and cracks. To date, H trapping at vacancies has attracted the most attention because it holds many surprises and mysteries as well as importance to engineering alloys. Through first-principles calculations, we have systematically performed the investigations of interaction of hydrogen with metal vacancies. We propose a unified mechanism involving charge transfer associated strain destabilization to understand H segregation behavior at vacancies. We discover that H prefers to occupy interstitials with high pre-existing charge densities and the availability of such interstitials sets the limit on H trapping capacity at a vacancy. Once the maximum H capacity is reached, the dominant charge donors switch from the nearest-neighbor to the next-nearest-neighbor metal atoms. Accompanying with this long-range charge transfer, the sharply increased reorganization energy would occur, leading to the instability of the H-vacancy complex. The physical picture unveiled here appears universal across the BCC and FCC series and is believed to be relevant to other metals/defects as well. In addition, this mechanism can be also applied to the interpretation of hydrogen interacting with high density ultrafine and ultrastable Ti-Y-O nanoparticles in ODS steels.

报告人姓名：陈星秋

报告人简介：陈星秋, 中国科学院金属研究所研究员,博士生导师,中科院百人计划。1998年东北大学材料与冶金学院钢铁冶金专业毕业，2005年奥地利维也纳大学物理化学研究所博士毕业。随后在美国橡岭国家实验室材料科学与工程部材料理论组做博士后研究。主要从事合金计算设计的新方法、新模型、新机理及应用探索研究。迄今为止，在国际刊物（Nature Chemistry，Nature Communications，7篇Phys. Rev. Lett.，26篇 Phys. Rev. B，1篇 Adv. Mater.等）发表论文70余篇，发表学术论文迄今被SCI杂志他引1800余次，H-index为24，5篇论文SCI引用超百次。参与承办和组织大型的计算材料国际会议（比如CDSM 2015）或者分会。当前担任Journal of Materials Science and Technology、Science China Materials、Scientific Report和 Metals四个杂志的编委。

报告人单位：中国科学院金属研究所  

报告时间：2015-11-25 09:00

报告地点：宝山校区E415室