Thermodynamic modeling of the C–RE (RE=La, Ce and Pr) systems

The phase diagrams and thermodynamic properties of the C–RE (RE=La, Ce and Pr) binary systems were assessed by using the CALPHAD method applied to the experimental data in the literature. In the C–RE (RE=La, Pr) systems, RE2C3 and βREC2 (high-temperature form of REC2 phase) were modeled as non-stoichiometric phases while αREC2 (low-temperature form of REC2 phase) was considered to be stoichiometric phase. For La2C3 phase, enthalpy increment (HT–H298K) information was also considered in the optimization. Due to their negligible homogeneities, intermediate compounds Ce2C3 and CeC2 in the C–Ce system, were treated as stoichiometric phases. One set of self-consistent thermodynamic parameters was finally obtained for each of these binary systems. Comparisons between calculated and measured phase diagrams as well as thermodynamic properties showed that most of the experimental information can be satisfactorily accounted for by the present thermodynamic descriptions.