Abstract Electrolysis of molten fluorides is one of the promising methods for the recovery and recycling of rare earth metals from used magnets. Due to the dearth of phase equilibria data for molten fluoride systems, thermodynamic modelling of LiF-DyF3-NdF3 system using the CALPHAD approach was carried out. Gibbs energy modelling for LiF-NdF3 and LiF-DyF3 systems was performed using the constitutional data from literature. Ab initio calculations were used to obtain enthalpy of reaction of LiDyF4, an intermediate phase that is found to exist in the LiF-DyF3 system. Differential thermal analysis was carried out for selected compositions in the NdF3-DyF3 system, in order to determine liquidus and solidus temperatures. The Gibbs energy parameters for the limiting binaries determined in this work is used for modelling the Gibbs energy functions of equilibrium phases in the ternary system. Selected compositions of LiF-NdF3-DyF3 were subjected to DTA in order to validate the calculated phase temperatures involving melt.

中文翻译：

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LiF-NdF 3 -DyF 3 体系的实验研究和热力学建模

摘要 电解熔融氟化物是从废磁铁中回收和回收稀土金属的一种很有前景的方法。由于缺乏熔融氟化物系统的相平衡数据，使用 CALPHAD 方法对 LiF-DyF3-NdF3 系统进行了热力学建模。LiF-NdF3 和 LiF-DyF3 系统的 Gibbs 能量建模是使用文献中的结构数据进行的。从头算计算用于获得 LiDyF4 的反应焓，LiDyF4 是发现存在于 LiF-DyF3 系统中的中间相。对 NdF3-DyF3 系统中选定的成分进行差热分析，以确定液相线和固相线温度。在这项工作中确定的极限二元的吉布斯能量参数用于模拟三元系统中平衡相的吉布斯能量函数。对选定的 LiF-NdF3-DyF3 组合物进行 DTA，以验证计算出的涉及熔体的相温度。