无机材料学报

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HfxTa1-xC体系力学性能及熔化曲线的第一性原理研究

吴玉豪, 彭仁赐, 程春玉, 杨丽, 周益春   

  1. 陕西省空天高电子轨道材料与防护技术重点实验室,西安电子科技大学先进材料与纳米科技学院,西安 710126
  • 收稿日期:2023-11-06 修回日期:2024-02-28
  • 作者简介:吴玉豪(2000-), 男, 硕士研究生. E-mail: hsarfr@163.com.
  • 基金资助:
    国家自然科学基金(11890684, 12302125); 中央高校基本科研业务费(20101237677, ZYTS23079)

First-principles Study on Mechanical Properties and Melting Curve of HfxTa1-xC System

WU Yuhao, PENG Renci, CHENG Chunyu, YANG Li, ZHOU Yichun   

  1. Shaanxi Key Laboratory of High-Orbits-Electron Materials and Protection Technology for Aerospace, School of Advanced Materials and Nanotechnology, Xidian University, Xi’an 710126, China
  • Received:2023-11-06 Revised:2024-02-28
  • About author:WU Yuhao (2000-), male, Master candidate. E-mail: hsarfr@163.com
  • Supported by:
    National Natural Science Foundation of China(11890684, 12302125); the Fundamental Research Funds for the Central Universities of China (20101237677, ZYTS23079)

摘要: HfxTa1-xC具有高熔化温度、高硬度、高强度、高导电导热性等优异性能,是2000 °C以上热防护领域极有潜力的候选材料,但其力学性质与熔化温度随组分变化规律尚不清晰。本研究基于特殊准随机结构(SQS)方法和第一性原理计算,从键强、价电子浓度(VEC)的微观角度系统地探讨了Hf-Ta-C系固溶体力学性质随组分的变化机理。力学性质计算结果表明:5种组分(HfC、Hf0.75Ta0.25C、Hf0.5Ta0.5C、Hf0.25Ta0.75C与TaC)中,Hf0.25Ta0.75C固溶体具有最高的弹性模量和剪切模量,这主要归因于: (i)该组分具有最强的键强;(ii)来自C的p轨道和来自Hf或Ta的d轨道之间的特殊键合在VEC=8.75(Hf0.25Ta0.75C)附近完全填充,它们强烈抵抗形状变化。研究还使用基于AIMD的分子动力学Z方法计算了HfxTa1-xC固溶体的熔化曲线。结果显示Hf-Ta-C系固溶体熔化温度反常增加的现象的确存在,且在Hf0.5Ta0.5C处熔化温度最高(4270 K),这主要归因于构型熵与共价键强度的协同作用。研究结果为实验上高熔化温度及高力学性能Hf-Ta-C系固溶体组分的选择及其耐高温涂层应用等提供了理论指导,也为其他的过渡金属碳化物研究提供了参考。

关键词: HfxTa1-xC材料, 第一性原理, 力学性质, 熔化温度

Abstract: HfxTa1-xC solid solution is a very promising candidate for thermal protection materials above 2000 °C due to its excellent properties such as high melting point, high hardness, high strength, high electrical conductivity and high thermal conductivity. However, the mechanism of its mechanical properties and melting temperature varying with the composition remains elusive. Firstly, we systematically investigated the mechanism of the variation of mechanical properties of Hf-Ta-C system solid solutions with its components from the microscopic point of view of bond strength and valence electron concentration (VEC) based on the Special Quasirandom Structures(SQS) method and first-principle calculations. It revealed that among the five components of solid solutions (i.e., HfC, Hf0.75Ta0.25C, Hf0.5Ta0.5C, Hf0.25Ta0.75C and TaC), the Hf0.25Ta0.75C solid solution possessed the largest elastic modulus and shear modulus. It was mainly attributed to two reasons: (i) this component possessed the strongest bonding strength among the above ternary compounds; (ii) the special bonding states between the p-orbitals from C and the d-orbitals from Hf or Ta strongly resisted the deformation and were completely filled near VEC=8.75 (for Hf0.75Ta0.25C). Secondly, the melting curves of the Hf-Ta-C system solid solutions were calculated using the AIMD-based molecular dynamics Z method. It showed that there existed indeed the phenomenon for anomalous increase in the melting point of Hf-Ta-C solid solutions, and the highest melting temperature of 4270 K was predicted at Hf0.5Ta0.5C, which was mainly attributed to the synergistic effect of the conformational entropy and the strength of the covalent bond. The results provide theoretical guidance for the experimental selection of the optimal components of high melting point and high mechanical properties for Hf-Ta-C solid solutions in the thermal barrier coating applications, as well as a reference for the study of other transition metal carbides.

Key words: HfxTa1-xC system, First-principles method, mechanical property, melting temperature

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