Thermodynamic modeling of the Nb-rich corner in the Nb–Si–Sn system

A thermodynamic description for the Nb–Si–Sn system has been developed on the basis of the constituent binaries and critically reviewed ternary experimental data. The published thermodynamic descriptions for the Nb–Si and Nb–Sn binaries were directly used and that for the Si–Sn binary was remodeled in the present study. A two-sublattice model, (Nb,Si,Sn)3 (Nb, Si, Sn), was applied to the A15 phase considering its crystal structure and homogeneity range. The isothermal sections at 1600 °C, 1500 °C, 1200 °C and 900 °C, the liquidus projection and the solidification path of the alloy (Nb–18Si–5Sn) were calculated accordingly based on the currently obtained thermodynamic description and compared with the experimental results. Comparison between the calculated results and the experimental measurements shows that the present modeling can provide a satisfactory account of the experimental information for the Nb-rich corner of the Nb–Si–Sn ternary phase diagram.