Thermodynamic modelling of magnetic laves phase in Fe–Ti system using first principle method

Phase diagram calculation of Fe–Ti system is obtained by coupling of CALPHAD with first principle methods. Single Gibbs energy model is used for FeTi to take care of order-disorder transition. First principle calculation shows that Laves phase is ferromagnetic nature with the magnetic moment of 1.417μB which is incorporated in the modelling. For extrapolation to higher order system, Laves phase is mostly expressed with two sublattice model. From crystallographic view, 3 sublattice model is appropriate one for description of Laves phase. Hence, two different models are used for Laves phase. Wagner-Schottky model used to describe the homogeneity region of Laves phase in two sublattice model. Using the first principle method, the energies of formation of unstable end members of FeTi phase and three sublattice model of Laves phase are calculated and incorporated as experimental data in optimisation. Calculated phase diagram and the thermochemical properties using 3 sublattice model of Laves phase shows good agreement with the experimental data. •Magnetism of Laves phase confirmed with First principle calculation and incorporated in Modelling.•Single Gibbs energy model is used for BCC and B2(FeTi) phase.•Energy of end members of FeTi and Laves phase are calculated by first principle method.•Calculated phase diagram is compared with two and three sublattice models of Laves phase.