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Thermodynamic reassessment of the Mo–Hf and Mo–Zr systems supported by first-principles calculations
Calphad ( IF 2.4 ) Pub Date : 2020-03-28 , DOI: 10.1016/j.calphad.2020.101766
Ruiqi Zhao , Jiong Wang , Huimin Yuan , Biao Hu , Yong Du , Zhunli Tan

Based on the experimental phase equilibria and thermodynamic data available in the literature and enthalpies of formation computed from first-principles calculations, the thermodynamic reassessment of the Mo–Hf and Mo–Zr systems was carried out by means of the CALPHAD (CALculation of PHAse Diagram) method. The enthalpies of formation for stable and metastable Laves (C15, C36, C14) phases and enthalpy of mixing for the β(bcc) solid solution phase in dilute solution were predicted via first-principles calculations to supply the necessary thermodynamic data for the modeling in order to obtain the thermodynamic parameters with physical sound meaning. The relative stability of Laves C14, C15 and C36 in the systems was discussed. The solution phases, i.e. liquid, β(bcc) and α(hcp) were described by the substitutional solution model, and all the Laves phases in the systems were described using two sublattice model. A set of self-consistent thermodynamic parameters were obtained for these binary systems, which agrees well with the experimental data in the literature. Based on these results, the trend of the site occupancy fraction of Laves phase changing with temperature was predicted. The isothermal section and the liquidus projection of Mo-Hf-Zr system were also predicted by combing with the Zr–Hf system reported in the literature.



中文翻译:

第一性原理计算支持的Mo-Hf和Mo-Zr系统的热力学重新评估

根据文献中可获得的实验相平衡和热力学数据以及根据第一性原理计算得出的生成焓,通过CALPHAD(对PHAse图的计算)对Mo–Hf和Mo–Zr系统进行了热力学重新评估。 ) 方法。通过第一性原理计算来预测稳定和亚稳态Laves(C15,C36,C14)相的形成焓和稀溶液中β(bcc)固溶体相的混合焓,以提供必要的热力学数据,以进行建模以获得具有物理意义的热力学参数。讨论了Laves C14,C15和C36在系统中的相对稳定性。用替代溶液模型描述了溶液相,即液体β(bcc)和α(hcp),使用两个亚晶格模型描述了系统中所有的Laves相。对于这些二元系统,获得了一组自洽的热力学参数,与文献中的实验数据非常吻合。根据这些结果,预测了Laves相的位点占有率随温度变化的趋势。Mo-Hf-Zr系统的等温截面和液相线投影也可以通过结合文献报道的Zr-Hf系统进行预测。

更新日期:2020-04-20
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