βTi-Nb合金的电子结构计算

发布时间：2018-06-23 15:09

本文选题：第一原理 + 钛合金　；参考：《辽宁大学》2017年硕士论文

【摘要】：从发现钛合金优秀力学性能起,人们对它的研究就从未止步。由中科院沈阳金属研究所开发的新型钛合金Ti2448是一款新型医用钛合金。该合金表现出了更卓越的力学性能,不过对其微观变化机理还不明确。本文采用基于密度泛函理论的第一原理计算方法,运用VASP软件包对βTi-Nb合金的电子结构进行初步研究的基础上,继续对不同构型下不同Nb含量的βTi-Nb合金的电子结构进行更细致的理论计算。为研究Ti2448合金的微观机制的分子动力学模拟和开发势函数提供数据支持。本课题组初步计算过程中发现βTi-Nb在Nb含量为35at%~65at%之间对Vegard定律有明显的偏移。我们的计算针对的是Nb含量在这一范围内的βTi-Nb合金。通过结合能的计算发现合金稳定性随着Nb含量的增加而提高,合金不易形成有序相;随着Nb含量的增加,态密度图中的赝能隙变宽,费米能级降低说明合金不易氧化,抗氧化性升高;合金的分波态密度对比发现βTi-Nb合金体系的态密度主要由Ti-Nb的d轨道电子提供;为了更加直观的了解原子间成键情况,本文计算了βTi-Nb合金的电荷差分密度并绘制了差分电荷密度图,分析发现:Nb-Nb键之间表现出较强的共价性,形成很强的共价键,所以随着Nb含量的增加合金中电子的局域性和方向性增强,结构也更加稳定;在计算βTi-Nb合金的电子结构的同时,还计算了Ti-Nb基体中的杂质间的相互作用。结果表明:Nb基体中Ti杂质间具有相互排斥作用,而在Ti基体中的Nb杂质具有相互吸引的作用。
[Abstract]:Since the discovery of excellent mechanical properties of titanium alloys, the study of titanium alloys has never stopped. A new titanium alloy Ti2448 developed by Shenyang Institute of Metals of Chinese Academy of Sciences is a new medical titanium alloy. The alloy exhibits more excellent mechanical properties, but the mechanism of microcosmic change is not clear. In this paper, the first principle method based on density functional theory is used to study the electronic structure of 尾 Ti-Nb alloy by using VASP software package. The electronic structures of 尾 Ti-Nb alloys with different NB contents in different configurations were calculated in detail. It provides data support for molecular dynamics simulation and development potential function of micromechanism of Ti2448 alloy. During the preliminary calculation of 尾 Ti-Nb, we found that 尾 Ti-Nb deviated from Vegard's law obviously between the NB content of 35atum and 65at%. Our calculations are for 尾 Ti-Nb alloys with NB content in this range. Through the calculation of binding energy, it is found that the stability of the alloy increases with the increase of NB content, and the ordered phase is not easily formed, and with the increase of NB content, the pseudo-energy gap in the density of states diagram becomes wider, and the decrease of Fermi energy level indicates that the alloy is not easy to oxidize. The density of states of 尾 Ti-Nb alloy system is mainly supplied by the d-orbital electrons of Ti-Nb alloy system, and in order to understand the bonding between atoms more intuitively, the density of states of 尾 Ti-Nb alloy system is mainly supplied by the d-orbital electrons of Ti-Nb alloy system. In this paper, the charge differential density of 尾 Ti-Nb alloy is calculated and the differential charge density diagram is plotted. It is found that there is a strong covalent bond between the 2: Nb-Nb bonds, and a very strong covalent bond is formed. Therefore, with the increase of NB content, the electron localization and directivity in the alloy become more stable, and the interaction between impurities in Ti-Nb matrix is also calculated while the electronic structure of 尾 Ti-Nb alloy is calculated. The results show that the Ti impurity is mutually repulsive and the NB impurity in the Ti matrix is attractive to each other.
【学位授予单位】：辽宁大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG146.23

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