Phase equilibria in the ZrO2–Ta2O5–Nb2O5 system: Experimental studies and thermodynamic modeling
Phase equilibria in the ZrO2–Ta2O5–Nb2O5 system: Experimental studies and thermodynamic modeling
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ZrO2→Ta2O5→Nb2O5 体系中的相平衡：实验研究和热力学建模
DOI：
10.1111/jace.18079
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发表时间：
2021
影响因子：
3.9
通讯作者：
Yong Du
中科院分区：
文献类型：
--
作者：
Peide Luo;Xiang Wu;Wenhui Xiao;Fan Zhang;Yao Wang;D;an Huang;Yong Du
对ZrO_2-Ta_2O_5-Nb_2O_5系统的相关系进行了实验研究，并进行了热力学模拟。采用共沉淀法合成了具有所选组成的样品，并分别在1573和1673 K下进行了平衡。在X射线衍射（XRD）和扫描电子显微镜（SEM/EDX）的支持下进行微观结构表征和相分析。通过差热分析（DTA）测量相变。没有三元化合物存在，而Ta 2 O 5和Nb 2 O 5相基本上延伸到三元系统。此外，二元Ta_2Zr_6O_（17）和Nb_2Zr_6O_（17）相在三元体系中形成连续固溶体（A_2Zr_6O_（17））。推测了β-Ta 2 O 5 + A2 Zr 6 O 17 + Nb 2 O 5的三相平衡区。本文在现有文献的基础上，用相图计算法（CALPHAD）对ZrO_2-Nb_2O_5、ZrO_2-Ta_2O_5和Nb_2O_5-Ta_2O_5二元系进行了评价和优化。结合二元体系的热力学参数，外推了三元体系的相关系。然而，外推法不能再现我们的实验结果，特别是对于ZrO 2在Ta 2 O 5和Nb 2 O 5相中的三元溶解度和所选样品的熔化行为。最后，引入了三元混合参数，改进的热力学描述与实验数据吻合较好。
The phase relations in the ZrO2–Ta2O5–Nb2O5system were experimentally investigated, and thermodynamic modeling was consequently performed in the present work. Samples with the selected compositions were synthesized using coprecipitation method, and then separately equilibrated at 1573 and 1673 K. The microstructural characterizations and phase analyses were carried out with the support of the X‐ray diffraction (XRD) and scanning electron microscopy (SEM/EDX). The phase transformations were measured through differential thermal analysis (DTA). No ternary compounds exist, while Ta2O5and Nb2O5phases substantially extend into the ternary system. Moreover, binary Ta2Zr6O17and Nb2Zr6O17phases form a continuous solid solution (A2Zr6O17) in the ternary system. A three‐phase equilibrium region β‐Ta2O5+ A2Zr6O17+ Nb2O5was speculated. Based on the available literature, the ZrO2–Nb2O5, ZrO2–Ta2O5, and Nb2O5–Ta2O5binary systems were critically evaluated and optimized by means of the CALPHAD (CALculation of PHAse Diagram) method. Combining with thermodynamic parameters of the binary systems, phase relations in the ternary system were extrapolated. However, the extrapolation cannot reproduce our experimental results, especially for the ternary solubilities of ZrO2in the Ta2O5and Nb2O5phases and the melting behavior of selected samples. Finally, the ternary mixing parameters were introduced, and our experimental data were well reproduced by the improved thermodynamic descriptions.