Sharma Shambhu Bhandari, Mehta Shailesh, Alfè Dario
Department of Earth Sciences, University College London, Gower Street, London WC1E 6BT, United Kingdom.
AWE Nuclear Security Technologies, Aldermaston, Reading, Berkshire RG7 4PR, United Kingdom.
J Chem Phys. 2025 May 14;162(18). doi: 10.1063/5.0264856.
Phase diagrams are crucial to the design of new materials, to understand their phase stability and metastability under different thermodynamic conditions, such as composition, temperature, and pressure. Here, we use an ab initio approach to study the phase diagram of a binary alloy within the low concentration limit of a solute. Using the ab initio molecular dynamics calculations based on density functional theory, we estimate the solute partitioning ratios in solid-liquid phase equilibria. The chemical potential difference between the solvent and solute atoms in both solid and liquid phases is calculated using thermodynamic integration. As an illustration of the techniques, we have applied this method to reproduce the phase diagram of the Al-Mg alloy at zero pressure. We also compute the ab initio solid-liquid coexistence curve of pure Al by applying the phase-coexistence method with the free energy correction technique. The calculated results are in close agreement with the experiment, demonstrating the reliability of the models.
相图对于新材料的设计、理解其在不同热力学条件（如成分、温度和压力）下的相稳定性和亚稳定性至关重要。在此，我们采用从头算方法研究溶质低浓度极限下二元合金的相图。基于密度泛函理论进行从头算分子动力学计算，我们估算了固 - 液相平衡中的溶质分配比。利用热力学积分计算固液两相中溶剂和溶质原子之间的化学势差。作为该技术的一个示例，我们已应用此方法重现了零压力下Al - Mg合金的相图。我们还通过应用具有自由能校正技术的相共存方法计算了纯Al的从头算固 - 液共存曲线。计算结果与实验结果密切吻合，证明了模型的可靠性。
