Thermodynamic optimization of the Nb-Si-W ternary system

Based on the experimental measurements of the liquidus projection and the isothermal sections, the Nb-Si-W ternary system is thermodynamically assessed using the CALPHAD (CALculation of PHAse Diagram) approach. The parameters for the thermodynamic descriptions of all the phases in the system are optimized, following the reported descriptions of the three constituent binaries the Nb-Si, the Nb-W and the Si-W systems. Some of the parameters of the Si-W system are modified according to its related binary experimental data. The comparisons between the calculated liquidus projection and isothermal sections and the experimental ones show that the present modeling can finely describe the experimental results of the Nb-Si-W ternary system. The solidification analyses can explain the microstructure evolutions for typical ternary alloys.