纳米结构铁素体合金中氦捕获的第一性原理研究

发布时间：2018-12-25 07:42

【摘要】：基于第一性原理计算研究纳米结构铁素体合金(NFAs)对中子辐照引发的氦的选择性捕获能力。结果表明与铁基体中的空位相比,氦更容易被NFAs中Y_2Ti_2O_7的八面体间隙和Y_2TiO_5沿b轴方向的中空通道捕获;被氧化物捕获的氦相互间存在排斥作用,说明氦在NFAs中的分散度将在很大程度上取决于氧化物的析出分数和弥散度;通过计算界面相图推断,铁素体/Y_2Ti_2O_7界面应为富Y/Ti型,与实验观测到的Y_2Ti_2O_7析出相的非化学计量比特性吻合;氦对Fe/Y_2Ti_2O_7界面有较强的偏聚倾向,且可能对氧化物颗粒尺寸敏感。较大尺度的Y_2Ti_2O_7能够将氦捕获在界面和体内,而低纳米尺度的Y_2Ti_2O_7更倾向于将氦捕获在界面。
[Abstract]:The selective capture ability of nanoscale ferrite alloy (NFAs) for helium induced by neutron irradiation was investigated based on first principle calculation. The results show that helium is more easily captured by the octahedron gap of Y_2Ti_2O_7 in NFAs and the hollow channel of Y_2TiO_5 along b axis than the vacancies in iron matrix. The repulsion of helium trapped by oxides indicates that the dispersion of helium in NFAs depends to a great extent on the precipitation fraction and dispersion degree of the oxides. It is inferred from the calculation of the boundary phase diagram that the ferrite / Y_2Ti_2O_7 interface should be Y/Ti rich, which is consistent with the non-stoichiometric ratio of the Y_2Ti_2O_7 precipitates observed experimentally. Helium has a strong segregation tendency to Fe/Y_2Ti_2O_7 interface and may be sensitive to oxide particle size. Large scale Y_2Ti_2O_7 can capture helium at interface and in vivo, while low nanometer scale Y_2Ti_2O_7 is more inclined to capture helium at interface.
【作者单位】：中南大学材料科学与工程学院;中南大学粉末冶金国家重点实验室;中南大学有色金属材料科学与工程教育部重点实验室;清华大学材料科学与工程学院;北京科技大学材料科学与工程学院;东北大学材料与冶金学院;
【基金】：国家自然科学基金资助项目(51471189,51171211,51471049) 国家重点基础研究发展计划资助项目子课题(NC2014CB644001-2) 中南大学粉末冶金国家重点实验室自主项目
【分类号】：TG142.1

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