Mo-RE二元合金相图的热力学数据库

Thermodynamic Database for the Mo-RE Binary Alloy Systems

摘要:

利用CALPHAD方法,选择和建立合理的热力学模型,并结合相平衡及热力学性质的相关实验信息,对Mo-RE (RE: Ce, Pr, Nd, Sm, Eu, Tb, Ho, Er, Tm, Yb, Lu)各二元系相图进行了热力学优化与计算。其中,液相和端际固溶体相的Gibbs自由能采用亚正规溶体模型描述,气相的Gibbs自由能采用理想气体模型描述。计算结果与实验数据取得了良好的一致性,最终得到了一组自洽的合理描述Mo-RE二元系各相自由能的热力学参数,建立了Mo-RE (RE: Ce, Pr, Nd, Sm, Eu, Tb, Ho, Er, Tm, Yb, Lu)二元合金相图的热力学数据库。该热力学数据库可以提供相平衡及热力学性质等多种信息,为外推计算三元以及更多组元体系的相平衡提供理论基础,并为相关体系的合金设计及制备提供重要的理论指导。

Abstract:

Thermodynamic database of the Mo-RE (RE: Ce, Pr, Nd, Sm, Eu, Tb, Ho, Er, Tm, Yb, Lu) systemswas developed for the design of the Molybdenum-based refractory alloys. The thermodynamic calculation and optimization of Mo-RE binary systems have been performed using the Calculation of Phase Diagrams (CALPHAD) method on the basis of experimental data including phase equilibria and thermodynamic properties. The Gibbs energies of the liquid and solid solution phases are described by the sub-regular solution model, whereas those of the gas phases are described by the ideal gas model. The present work obtained a set of self-consistent thermodynamic parameters that reasonably describes the thermodynamic properties of the Mo-RE binary systems. A good agreement between calculation results and experimental data was reached. The utility of this database is demonstrated in the examples of thermodynamic calculations of the mixing enthalpy of liquid phase in the Mo-Ce and Mo-Pr system. Also, the 1200, 1300, 1400oC isothermal section diagrams of the Mo-Ho-Tb system and the related property diagrams like phase fraction of desired phases were depicted. Meanwhile, the Mo-Cu-Er ternary phase equilibria sections from 800 to 1000oC were extrapolated. These results show fairly good predictions and provide much-needed information for the alloy design of the Molybdenum-based refractory materials.