Calphad-based thermodynamic assessment of Sm-In binary system supported by Ab-initio calculations

Abstract

The Calphad method was employed to assess the phase equilibria and thermodynamic characteristics of the samarium-indium system. The input data included theoretical and experimental information, as well as calculated data pertinent to this system. The objective was to identify the equilibrium phase and unknown thermodynamic properties of the system. This entailed determining the parameters that govern the Gibbs energy associated with each distinct phase. The Samarium-Indium system comprises five intermetallic compounds: Sm3In, Sm2In, SmIn3, SmIn, and Sm3In5. The three phases, Sm3In, Sm2In, and SmIn3, have been identified as stoichiometric compounds, while the two phases, SmIn and Sm3In5, exhibit a degree of homogeneity. These phases have been modeled using a two-sublattice model with substitution in each sublattice. A density functional theory (DFT) approach was employed to calculate the enthalpies of formation for all five phases. The Gibbs energy of the liquid phase (G) was described based on the Redlich-Kister equations. The crystal structure of the pure element Sm is Rhombohedral, while that of in is tetragonal. The calculations based on the thermodynamic modeling are in good agreement with the phase diagram data and experimental thermodynamic values available in the literature. The process of modeling allows us to calculate the phase equilibria and thermodynamic properties of the liquid phase and intermetallic compounds of the system Sm-In for the first time. The results obtained are reported in a series of figures and tables in this manuscript.