Thermodynamic assessment of the Ta–Ge system supported by ab initio calculations.

The Ta–Ge system was thermodynamically modeled for the first time using the CALPHAD method incorporating both literature-derived phase equilibria data and new enthalpy of formation values for the intermetallic compounds. Density Functional Theory (DFT) calculations were employed to accurately determine enthalpy of formation values for key Ta–Ge compounds. The stable intermetallic phases (i.e., αTa 3 Ge, βTa 3 Ge, βTa 5 Ge 3 , and TaGe 2) were described as stoichiometric phases while the Liquid (L), Ta-rich solid solution (BCC-A2), and Ge-rich solid solution (Diamond-A4) were modeled as solution phases using the Compound Energy Formalism. Excess terms were described by the Redlich-Kister polynomials. The present thermodynamic model accurately describes phase equilibria and thermodynamic data, providing a reliable guide for designing alloys containing Ta and Ge. [ABSTRACT FROM AUTHOR]