Thermodynamic assessment of the Nb–Si–Mo system

Abstract

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 Nb 5Si 3 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 ) 5 Si 3 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.