Thermodynamic assessment of the Nb-Si-Mo system

Based on the experimental isothermal sections at 800, 1000, 1700 and 1800 °C and the liquidus projections from both the literature and the present measurements, the ternary Nb-Si-Mo system is thermodynamically assessed using the Calculation of Phase Diagram method (CALPHAD). The constituent Mo-Si binary system is reassessed according to its related binary experimental data. The sublattice model of the phase Nb5Si3 in the constituent Nb-Si binary system is modified as (Nb)0.5(Nb,Si)0.125(Nb,Si)0.375, in order to give the solid phase β(Nb,Mo)5Si3 in the Nb-Si-Mo ternary system a better description. The parameters of the thermodynamic descriptions of the Nb-Si-Mo ternary system are optimized following the reported Nb-Mo, the modified Nb-Si and the reassessed Mo-Si binary systems. The comparison between the calculated results and the experimental investigations shows that the present modeling can finely describe the experimental information of the Nb-Si-Mo ternary system.