Transactions of Nonferrous Metals Society of China The Chinese Journal of Nonferrous Metals

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中国有色金属学报

ZHONGGUO YOUSEJINSHU XUEBAO

第28卷    第8期    总第233期    2018年8月

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文章编号:1004-0609(2018)-08-1491-08
Al-Ti-B合金中AlB2、TiB2和TiAl3的第一性原理研究
黄元春1, 2, 3,邵虹榜1,肖政兵1, 2, 3,任贤魏1,郭晓芳1

(1. 中南大学 轻合金研究院, 长沙 410083;
2. 中南大学 高性能复杂制造国家重点实验室, 长沙 410083;
3. 中南大学 机电工程学院, 长沙 410083
)

摘 要: 采用基于密度泛函理论的第一性原理方法,研究0 K条件下Al-Ti-B体系中AlB2、TiB2和TiAl3的平衡晶格常数、形成热、结合能及电子特性,并结合准简谐德拜模型对3种物相在高温条件下的热力学基本性质进行了分析。计算结果表明:AlB2、TiB2和TiAl3的形成热与结合能均为负值,表明3种相均具有结构稳定性,且稳定性由大到小依次为TiB2、TiAl3、AlB2;3种物相的离子性与金属性由大到小依次为TiAl3、AlB2、TiB2,TiAl3与AlB2显示离子键特性,而TiB2键合特性以共价键为主;3种物相的热稳定性由大到小依次为TiB2、AlB2、TiAl3。计算所得TiB2、AlB2和TiAl3的热力学性质可以用于分析氟盐法制备Al-Ti-B时Al熔体与氟盐之间反应发生情况以及中间合金最终的物相组成。

 

关键词: Al-Ti-B合金;第一性原理;准简谐德拜模型;结构特性;热力学性质

First principle study of AlB2, TiB2 and TiAl3 in Al-Ti-B alloy
HUANG Yuan-chun1, 2, 3, SHAO Hong-bang1, XIAO Zheng-bing1, 2, 3, REN Xian-wei1, GUO Xiao-fang1

1. Light Alloy Research Institute, Central South University, Changsha 410083, China;
2. State Key Laboratory of High Performance and Complex Manufacturing, Central South University, Changsha 410083, China;
3. College of Mechanical and Electrical Engineering, Central South University, Changsha 410083, China

Abstract:The crystal structure, heat of formation, cohesive energy and electronic properties of AlB2, TiB2 and TiAl3 in Al-Ti-B system under 0 K condition were investigated by using first principles based on density functional theory, and the quasi-harmonic Debye model was performed to calculate the thermodynamic properties of these phases. The results show that the heat of formation and cohesive energy of AlB2, TiB2 and TiAl3 are both negative, which indicate that these phases possess structural stability, and the structural stability decreases in the order from big to little of TiB2, TiAl3, AlB2. The iconicity and metallicity of these compounds increase in the following sequence from big to little of TiAl3, AlB2, TiB2, and the dominant bonding in TiAl3 and AlB2 is ionic, while the bonding in TiB2 is mainly covalent. The thermodynamic calculation results show that the thermal stabilities of the three phases decrease in the order from big to little of TiB2, AlB2, TiAl3, which can be used to illustrate the reactions between Al melt and fluoride salts when preparing Al-Ti-B by fluoride salt process.

 

Key words: Al-Ti-B alloy; first-principles; quasi-harmonic Debye model; structural properties; thermodynamics properties

ISSN 1004-0609
CN 43-1238/TG
CODEN: ZYJXFK

ISSN 1003-6326
CN 43-1239/TG
CODEN: TNMCEW

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