A thermodynamic description of the Cr–Ge system

Abstract

The phase equilibria and thermodynamic properties of the Cr–Ge system were optimized using the CALPHAD (Calculation of Phase Diagram) technique. In the present work, the excess Gibbs energy of the liquid, body-centered cubic (bcc) and diamond solution phases were modeled with the Redlich–Kister equation. The excess Gibbs energies for the solution phases (liquid, bcc, diamond) were described using the polynomial temperature dependence and Kaptay equation. The intermetallic compounds Cr 3Ge, αCr 5Ge 3 and βCr 5Ge 3, which had homogeneity ranges, were treated with sublattice models Cr 3(Cr, Ge), α(Cr, Ge) 5Ge 3 and β(Cr, Ge) 5Ge 3, respectively. The intermetallic compounds Cr 11Ge 8, CrGe and Cr 11Ge 19 were treated as stoichiometric compounds. Two sets of self-consistent thermodynamic parameters were obtained and the calculated results were presented and compared with the experimental data.