Thermodynamic assessment of the Cr–Al–Nb system

Abstract

Abstract A thermodynamic assessment of the Cr–Al–Nb system was performed using the CALPHAD technique on the basis of new experimental data on three isothermal sections at 1 150, 1300 and 1 450 °C as well as the available earlier literature data. The ternary phase diagram is dominated by an extended phase field of the Laves phase Nb(Cr, Al)2. Both the cubic C15 and the hexagonal C14 structure type of Laves phases occur as stable phase in the ternary system. A two-sublattice model was used for their thermodynamic description. The ternary solubilities of the (Nb) and (Cr) solid solutions and the binary phases NbAl3, Nb2Al and Nb3Al were taken into account in the ternary assessment. Several isothermal sections were calculated using the evaluated parameters. Good agreement between the calculations and the experimental data is achieved.