氧在β钛合金中扩散的第一性原理研究
(中国科学院金属研究所 沈阳材料科学国家实验室，沈阳 110016)
摘 要: 利用第一原理平面波赝势方法研究β钛间隙原子氧与合金原子(Nb, Zr, Sn)相互作用以及氧在β钛中的扩散。氧在纯β钛中的扩散研究表明：在0 K下，由于β钛在低温下的结构不稳定性，氧在β钛中的稳定位置偏离高对称的八面体间隙位置，其扩散势能曲线为“W”型；随着电子温度的升高，β钛结构稳定性增加，扩散势能曲线趋于抛物线型。合金原子与氧的相互作用能计算结果表明，合金原子与其最近邻八面体中的氧相互排斥，与次近邻氧吸引。从合金原子与氧的化学作用及弹性作用两个角度对相互作用能进行分析。在TiNb中氧倾向于占据周围Ti原子较多且最近邻位置有Ti的八面体间隙。
关键字: β钛合金；第一性原理；间隙扩散；电子温度
（Shenyang National Laboratory for Materials Sciences, Institute of Metal Research, Chinese Academy of Sciences,
Shenyang 110016, China）
Abstract:A first-principles plane-wave pesudopotential method was used to study the interaction between the interstitial oxygen and alloying atom (Nb, Zr, Sn) as well as the diffusion of oxygen in β-Ti. It is shown that, at 0 K, the most stable location for oxygen in β-Ti is slightly away from the high-symmetry octahedral interstice, and the migration of oxygen exhibits ‘W’-type of profile due to the instability of β-Ti. With the elevating of electronic temperature, the stability of β-Ti increases, and the diffusion energy curve tends to behave normal parabolically shaped. From the calculated interaction between the alloying atom and oxygen, the alloying atoms repulse their first nearest oxygen, while attract the second nearest one. The calculated interaction energy was discussed in terms of the elastic and chemical interaction. In TiNb alloy, oxygen tends to occupy the octahedral interstices with more Ti atoms also with Ti in its nearest sites.
Key words: β-Ti alloy; first-principles; interstitial diffusion; electronic temperature
