Ti-Al金属间化合物的力热性能及其能带计算

发布时间：2018-02-03 04:39

本文关键词： Ti-Al合金密度泛函理论第一性原理热力性能电子结构　出处：《沈阳工业大学》2017年硕士论文　论文类型：学位论文

【摘要】：Ti-Al合金是一类倍受人们关注的重要材料,由于它具有优异的物理性能,因此它在航空航天、汽车制造等领域有着广泛而重要的应用。在Ti-Al合金的设计和应用中,往往需要对其有关力热性能和电子结构有较深入的了解和掌握,因此“Ti-Al金属间化合物的力热性能及其能带计算”论文具有重要的理论意义与价值。本文针对Ti-Al合金中的TiAl、TiAl_2、TiAl_3、Ti_3Al金属间化合物的有关力热性能和能带,采用基于密度泛函理论的第一性原理以及Materials Studio软件中的CASTEP软件包进行了理论计算。在计算过程中,首先利用广义梯度近似(GGA)中的PBE方法,对晶体的结构进行了几何优化,得出了平衡晶格常数。在此基础上,利用生成热和结合能相应的公式,计算得到了四种金属间化合物的生成热、结合能的具体数值。利用广义梯度近似(GGA)中的PW91方法对Ti-Al合金的各个相的弹性系数进行计算。以及对电子能带和电子态密度曲线进行了计算,并对计算结果进行了理论分析。计算结果表明:在上述四种金属间化合物中,由生成热、结合能的计算结果比较得出,在Ti-Al合金的四个相中Ti_3Al的合金化形成能力最强,而且结构也最稳定,通过对弹性系数的计算结果分析得出四种相的各种弹性系数,其中Ti_3Al相呈韧性,且抗变形能力最强,刚性也最强,体现出良好的综合力学性能。通过能带、态密度的计算与分析得出,上述四种合金都属于金属性材料,但是TiAl_3相的金属性较其另三种材料弱一些。其结果与其他学者实验及理论研究的结果基本相符。本文的计算结果为相关的理论及应用研究提供了有益的参考。
[Abstract]:Ti-Al alloy is a kind of important material which has been paid more attention to. Because of its excellent physical properties, Ti-Al alloy is widely used in aeronautics and astronautics. Automobile manufacturing and other fields have a wide range of important applications. In the design and application of Ti-Al alloys, it is often necessary to have a deeper understanding of their mechanical and thermal properties and electronic structure. Therefore, the paper "Ti-Al Intermetallics and their Energy Band calculation" is of great theoretical significance and value. This paper focuses on TiAlAlTiAl2 in Ti-Al alloys. The mechanical and thermal properties and energy bands of TiAl3AlTi3Al intermetallic compounds. The first principle based on density functional theory and the CASTEP software package in Materials Studio software are used to carry out theoretical calculation. Firstly, the PBE method in the generalized gradient approximation (GGA) is used to optimize the structure of the crystal, and the equilibrium lattice constant is obtained. On this basis, the corresponding formulas of heat of formation and binding energy are used. The heat of formation of four intermetallic compounds was calculated. Specific values of binding energy. Generalized gradient approximation (GGA). The PW91 method is used to calculate the elastic coefficients of each phase of Ti-Al alloy, and the electron band and density of state curves are calculated. The calculated results show that the heat of formation and binding energy are compared among the above four intermetallic compounds. Among the four phases of Ti-Al alloy, the forming ability of Ti_3Al is the strongest and the structure is the most stable. The elastic coefficients of the four phases are obtained by the analysis of the elastic coefficient. Among them, the Ti_3Al phase is ductile, with the strongest resistance to deformation and the strongest rigidity, which reflects the good comprehensive mechanical properties. The calculation and analysis of the energy band and density of states show that. The above four alloys are all metallic materials. However, the gold properties of the TiAl_3 phase are weaker than those of the other three materials. The results are in good agreement with the experimental and theoretical results of other scholars. The calculated results in this paper are useful for the relevant theoretical and applied research. For reference.
【学位授予单位】：沈阳工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG146.23

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