Abstract The thermodynamic properties of the Zr-Nb alloy are investigated at temperatures below 890 K with ab initio calculations. The solution energies of the bcc Nb-rich and hcp Zr-rich solid solutions obtained within the framework of density functional theory are in good agreement with experimental data, although insufficient for a quantitative description of the miscibility gap, for which non configurational entropy has to be accounted for. Whereas electronic free energies can be neglected, we show, using the harmonic approximation and the density functional perturbation theory, that both solution free energies are strongly modified by the contribution related to atomic vibrations. Considering this vibrational free energy leads to a good description of the phase diagram.

中文翻译：

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第一性原理在 Zr-Nb 合金中的溶解度

摘要 利用从头算计算研究了 Zr-Nb 合金在低于 890 K 的温度下的热力学性能。在密度泛函理论框架内获得的 bcc 富 Nb 和 hcp 富 Zr 固溶体的溶解能与实验数据非常一致，尽管不足以定量描述混相间隙，为此非构型熵必须被计入。虽然电子自由能可以忽略不计，但我们使用谐波近似和密度泛函微扰理论表明，两种解自由能都被与原子振动相关的贡献强烈修改。考虑到这种振动自由能，可以很好地描述相图。