Refractory elements are usually alloyed in the next-generation superalloys for better high-temperature stability and mechanical properties in the applications ranging from power plants to turbine blades in jet engines. Phase diagrams and thermodynamic models are the essential information for alloy design. Herein, the phase equilibria of the Mo–Nb-Re ternary system was investigated using the complementary methods including ab initio calculations at 0K, high-temperature experiments, and CALPHAD thermodynamic modeling. The ground-state formation enthalpy of the bcc, hcp, σ, and χ phases were determined. The as-cast Mo–Nb-Re alloy and those equilibrated at high temperatures (1973, 2173, and 2373K) were experimentally examined. With the ab initio energetics and high-temperature phase equilibria, the thermodynamic description (functions of Gibbs free energy) of the Mo–Nb-Re ternary system and subsystems was assessed or reassessed, which provides the foundation for further developments of superalloys.

耐火元素通常在下一代高温合金中制成合金，以在从发电厂到喷气发动机的涡轮叶片等各种应用中获得更好的高温稳定性和机械性能。相图和热力学模型是合金设计的基本信息。在此，使用补充方法研究了Mo–Nb-Re三元系的相平衡，包括在0K处从头算起，高温实验和CALPHAD热力学模型。确定了bcc，hcp，σ和χ相的基态形成焓。对铸态的Mo–Nb-Re合金以及在高温（1973、2173和2373K）下达到平衡的合金进行了实验检查。随着从头 能量和高温相平衡，对Mo-Nb-Re三元体系和子系统的热力学描述（吉布斯自由能的功能）进行了评估或重新评估，这为超级合金的进一步发展提供了基础。