Thermodynamic analysis of the phase equilibria in the Nb-Ni-Zr system
Thermodynamic analysis of the phase equilibria in the Nb-Ni-Zr system
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DOI：
10.2320/jinstmet.70.741
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发表时间：
2005-12
影响因子：
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通讯作者：
T. Tokunaga;S. Matsumoto;H. Ohtani;M. Hasebe
中科院分区：
文献类型：
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作者：
T. Tokunaga;S. Matsumoto;H. Ohtani;M. Hasebe
用calphhad方法对Nb-Ni-Zr体系的相平衡进行了热力学研究。为了实现二元体系的热力学描述，我们采用了前人对Nb-Ni、Ni-Zr和Nb-Zr体系的评价结果。然而，根据最近的二元和三元相平衡实验数据，对Ni-Zr体系的热力学参数进行了一些修正。用差示扫描量热法（DSC）测定了Ni为60 mol%， Zr为20 mol%时，Nb-Ni-Zr三元体系中液相的相界。结合DSC实验结果和报道的773 K和1073 K等温截面相界，对Nb-Ni-Zr三元体系的热力学参数进行了评价。计算结果与DSC计算结果和实验等温剖面相吻合。此外，通过将相图计算的热力学性质与davis - uhlmann动力学公式相结合，对Nb-Ni-Zr三元合金的非晶成形能力进行了评价。在观察到的金属玻璃形成成分范围内，计算出的临界冷却速率比观察到的非晶形成范围低一个或多个数量级。
A thermodynamic study of phase equilibria in the Nb-Ni-Zr system has been carried out experimentally and using CALPHAD method. To enable the thermodynamic description of the constituent binary systems, the results from a previous evaluation were adopted for the Nb-Ni, Ni-Zr and Nb-Zr systems. However, some modifications of thermodynamic parameters of the Ni-Zr system were made based on the recent experimental data on binary and ternary phase equilibria. The phase boundaries involving the liquid phase in the Nb-Ni-Zr ternary system at a constant 60 mol%Ni and 20 mol%Zr were determined experimentally by differential scanning calorimetry (DSC). Thermodynamic parameters of the Nb-Ni-Zr ternary system were evaluated by combining the experimental results from DSC with the reported phase boundaries of the isothermal sections at 773 and 1073 K. The calculated results reproduced the present DSC results as well as the experimental isothermal sections. Furthermore, the amorphous-forming ability of Nb-Ni-Zr ternary alloys has been evaluated by incorporating the thermodynamic properties from the phase diagram calculations into the Davies-Uhlmann kinetic formulations. The calculated critical cooling rates in the observed metallic glass forming compositional range were found to be lower than those in the observed amorphous forming range by one or more orders of magnitude.