C，N，O原子在金属V中扩散行为的第一性原理计算∗

摘要

Based on the density functional theory, the diffusion behaviors of C, N and O atoms in V metal are studied by using the first-principles calculation method. Firstly, the site occupations of C, N and O atoms in the interstitials of the bcc V lattice are discussed. The interactions of interstitial C, N and O atoms with V lattice are analyzed, and the influence of the electronic structure on the interaction is explored. The study results show that C, N and O atoms are more stable in octahedral interstice of V metal, and a relatively strong bonding interaction is formed between their 2p-electron and the 3d-electron of V metal. The diffusion barriers of C, N and O atoms are 0.89 eV, 1.26 eV and 0.98 eV, respectively. Thus, the expressions of their diffusion coefficients are obtained. Finally, the diffusion coefficients of C, N and O atoms are compared by the Arrhenius plot. Their diffusion coefficients are calculated at 500–1100 K, and the calculation results are consistent with experimental values.%基于密度泛函理论,采用第一性原理计算方法研究了C, N, O原子在金属V中的扩散行为.首先,讨论了C, N, O原子在V体心立方晶格中的间隙占位情况,分析了其在间隙位置与V晶格的相互作用,并探究了这种相互作用对金属V电子结构的影响.研究结果表明： C, N, O原子在V的八面体间隙位置更为稳定,并且C, N, O原子的2p电子与V的3d电子之间有比较强的成键作用； C, N, O原子的扩散势垒分别为0.89,1.26,0.98 eV,并得出了其扩散系数表达式；最后,通过阿仑尼乌斯关系图对比了三者在V中扩散系数的大小,并计算出体系温度在500—1100 K之间时其在V中的扩散系数,计算结果与实验值基本符合.