Experimental investigation and thermodynamic calculation of the phase equilibria in the Fe–Nb–Ti ternary system

The phase equilibria in the Fe–Nb–Ti ternary system at 1000 °C, 1100 °C and 1200 °C have been experimentally investigated on ternary equilibrated alloys by means of optical microscopy (OM), electron probe microanalysis (EPMA) and X-ray diffraction (XRD). The Fe–Ti binary system was reassessed and the Fe–Nb–Ti ternary system was thermodynamically optimized using the CALPHAD (Calculation of Phase Diagrams) method. The obtained self-consistent parameters describing the Gibbs energy of each phase in the Fe–Ti and Fe–Nb–Ti systems lead good agreement between the calculated results and most of experimental data.