Thermodynamic modeling of the U–Mn and U–Nb systems

The thermodynamic assessments of the U–Mn and U–Nb binary systems were carried out by using the CALPHAD (Calculation of Phase Diagrams) method incorporating experimental thermodynamic properties and phase equilibria. The Gibbs free energies of the liquid, bcc, fcc, αU and βU phases were described by the subregular solution model with the Redlich–Kister equation, and those of the intermetallic compounds (Mn2U and MnU6) in the U–Mn binary system were described by the two-sublattice model. The thermodynamic parameters of the U–Mn and U–Nb binary systems were optimized to reproduce the experimental data, and provide agreement with the experimentally determined phase diagram for each binary system.