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利用第一性原理计算,研究了氧原子在Nb中的扩散现象以及施加应变的影响,并对氧原子在Nb-Ti、Nb-Zr合金中的团簇化进行了计算分析。发现在单向应变下,在平行于应变方向上,氧原子的扩散势垒随着应变的增大不断减小,当应变为10%时,扩散激活能从初始的0.92eV降低至0.5eV左右;在垂直于应变方向上,氧原子更容易扩散至被拉长的八面体间隙中,即单向应变下氧原子会在Nb中沿应变方向聚集排列,这会在实际材料中导致应力的集中。计算研究了氧原子在Nb合金中的团簇化问题,发现在纯Nb中,氧原子倾向于均匀分布而不是形成氧原子对;添加合金元素Ti和Zr后,随着氧原子浓度的升高,氧原子对将在合金元素周围形成,Zr周围氧原子对的形成可使体系的能量降低0.29eV。
First-principles calculations were used to investigate the diffusion of oxygen atoms in Nb and the effect of strain on the microstructures. The clustering of oxygen atoms in Nb-Ti and Nb-Zr alloys was also calculated. It is found that under unidirectional strain, the diffusion barrier of oxygen atoms decreases with increasing strain parallel to the strain direction. When the strain is 10%, the diffusion activation energy decreases from the initial 0.92eV to 0.5eV ; In the direction perpendicular to the strain, the oxygen atoms diffuse more easily into the elongated octahedral interstices, that is, the unidirectional strain of oxygen atoms in the strain-accumulating direction in Nb will result in the concentration of stress in the actual material . Computation of oxygen atoms in the Nb alloy cluster problem found that in pure Nb, the oxygen atoms tend to be evenly distributed rather than the formation of oxygen atom pairs; addition of alloying elements Ti and Zr, with the oxygen atom concentration increases , Oxygen atom pairs will form around the alloying elements and the formation of oxygen atom pairs around Zr will reduce the energy of the system by 0.29 eV.