Temperature dependent phase stability of Ti(C1−xNx) solid solutions using first-principles calculations
Temperature dependent phase stability of Ti(C1−xNx) solid solutions using first-principles calculations
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DOI：
10.1016/j.ceramint.2016.09.209
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发表时间：
2017
影响因子：
5.2
通讯作者：
Jiwoong Kim;H. Kwon;Chang Woo Kwon
中科院分区：
文献类型：
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作者：
Jiwoong Kim;H. Kwon;Chang Woo Kwon
我们利用准调和近似的第一性原理计算研究了Ti（C1−xNx）固溶体的晶格动力学和温度依赖热力学相稳定性。用有限元法得到了声子色散和态密度。采用特殊的准随机结构来模拟Ti（C1−xNx）亚晶格中碳和氮原子的随机分布。通过将Ti（C1−xNx）的结构和弹性性能与先前的结果进行比较，得到了模型和计算的可靠性。碳、氮原子的随机混合对材料的弹性性能影响较小，但对材料的动态稳定性影响较大。利用固溶体的形成能研究了其热力学相稳定性。准谐波近似下的态声子密度在不同温度下得到了精确的形成能。富氮相的热力学稳定性随温度的升高有明显的变化，与富碳相相比，富氮相的稳定性下降较快。我们的研究结果为Ti（CN）固体解决方案提供了基本的见解，这将有助于支持Ti（CN）材料的使用和生产。
We investigated lattice dynamic and temperature-dependent thermodynamic phase stabilities of Ti(C1−xNx) solid solutions using first-principles calculations within the quasi-harmonic approximation. Phonon dispersion and density of states were obtained by the finite-element method. Special quasi-random structures were used to mimic the random distribution of carbon and nitrogen atoms in the sublattice of Ti(C1−xNx). The reliability of the models and calculations were obtained by comparing the structural and elastic properties of Ti(C1−xNx) with previous results. The random mixing of carbon and nitrogen atoms had a minor effect on the elastic properties, but greatly influenced the dynamic stability. Thermodynamic phase stability was investigated using the formation energy of the solid solutions. The phonon density of states with the quasi-harmonic approximation yielded accurate formation energies at various temperatures. Nitrogen-rich phases showed noticeable changes in thermodynamic stability with increasing temperature, and their phase stability decreased quickly in comparison with the carbon-rich phases. Our results provide fundamental insights into Ti(CN) solid solutions that will help underpin the use and production of Ti(CN) materials.