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过程工程学报 ›› 2022, Vol. 22 ›› Issue (3): 403-412.DOI: 10.12034/j.issn.1009-606X.221086

• 研究论文 • 上一篇    下一篇

轻质双相高熵合金Al20Li20Mg10Sc20Ti30热力学性质的第一性原理研究

王玮， 杨锦， 丁凝， 陈晓桃， 唐壁玉*   

  1. 广西大学化学化工学院，广西 南宁 530004
  • 收稿日期:2021-03-17 修回日期:2021-05-24 出版日期:2022-03-28 发布日期:2022-03-28
  • 通讯作者: 唐壁玉 tangbiyu@gxu.edu.cn
  • 作者简介:王玮(1994-)，男，河北省邯郸市人，硕士研究生，化学工程与技术专业，E-mail: 15830780238@163.com；唐壁玉，通讯联系人，E-mail: tangbiyu@gxu.edu.cn.
  • 基金资助:
    国家自然科学基金;广西自然科学基金

First-principles study of thermodynamic properties of lightweight dual-phase high-entropy alloy Al20Li20Mg10Sc20Ti30

Wei WANG,  Jin YANG,  Ning DING,  Xiaotao CHEN,  Biyu TANG*   

  1. School of Chemistry and Chemical Engineering, Guangxi University, Nanning, Guangxi 530004, China
  • Received:2021-03-17 Revised:2021-05-24 Online:2022-03-28 Published:2022-03-28

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摘要： 采用特殊准随机结构(Special Quasi-random Structure, SQS)处理高熵合金固溶体的化学无序性，并基于密度泛函理论研究了具有面心立方(Face-centered Cubic, FCC)和密排六方(Hexagonal Close-packed, HCP)结构的Al20Li20Mg10Sc20Ti30高熵合金的结构稳定性和热力学性质。理论得到的两个相的晶格常数与实验测量值符合较好。两相中，由于HCP相具有较FCC相略大的体模量，因而其具有较好的抗压缩性能。由于计算得到的两个相在0 K时的形成焓都为小的正值，因而两个相都为热力学亚稳结构。采用Debye-Grüneisen模型研究了不同温度下两个相的热力学性质，结果表明两个相的体模量随温度的上升表现出缓慢的下降趋势，且HCP相的体模量大于FCC相，而FCC相具有更大的体积热膨胀系数。研究了两个相的熵(包括振动部分的贡献和电子部分的贡献)随温度的变化，结果表明在研究的温度范围内，HCP相比FCC相具有更大的熵，且两个相的熵的主要来源都为振动部分的贡献。

关键词: 高熵合金, 结构稳定性, 热力学性质, 从头计算, Debye-Grüneisen模型

Abstract: High-entropy alloys (HEAs) have attracted plenty of attention over the past decade due to their excellent properties. Compared with face-centered cubic (FCC) or body-centered cubic (BCC) structure, hexagonal close-packed (HCP) structure is rarely found in the single-phase random solid solution of HEAs, and most existing HCP HEAs are composed of rare earth (RE) elements. As a novel HEA, Al20Li20Mg10Sc20Ti30 possess two phases including FCC and HCP phase. And the RE elements in Al20Li20Mg10Sc20Ti30 are only one (Sc), showing that it may open up a new way for the design of less-RE HCP HEAs. Moreover, the advantage of low density about 2.67 g/cm3 indicates the tremendous potential of it in aeronautics and prosthetic devices, etc. In this work, the structure stability and thermal properties of face-centered cubic (FCC) and hexagonal close-packed (HCP) Al20Li20Mg10Sc20Ti30 HEAs are studied from density functional theory in which the chemical disorder of completely random solid solution are treated using the special quasi-random structure (SQS). The theoretical lattice constants for both structures are in good agreement with experimental measurements, and HCP phase has better compressibility resistance due to slightly higher bulk modulus. Both HCP and FCC structures are thermodynamic metastable due to slightly positive formation enthalpies and the chemical bond in HCP is more covalent due to its broader pseudogap. Applying Debye-Grüneisen model, thermal properties of HCP and FCC Al20Li20Mg10Sc20Ti30 are studied under different temperatures. Results show that the bulk modulus of both phases decline gently as temperature increases, and bulk modulus of HCP phase is usually larger. By comparison, FCC phase possesses lager volumetric thermal expansion coefficient. Specifically, temperature dependence of thermal entropy for both phases, including vibrational and electronic contribution, is investigated in details, finding that the HCP has a larger entropy than FCC at investigated temperature range, and the entropies of both phases originate predominantly from the vibrational contribution.

Key words: high-entropy alloys, structural stability, thermal properties, ab-initio calculations, Debye-Grüneisen model