Thermodynamic assessment of the Fe–Al–Zr phase diagram

The thermodynamic assessment of the Fe–Al–Zr ternary system was performed using the CALPHAD technique. The four published isothermal sections at 1073, 1173, 1273 and 1423 K, together with the proposed liquidus surface and the corresponding invariant reaction scheme, were taken into account. The reliability of the previous binary assessments was checked for the systems of interest, namely, for the Fe–Zr, Zr–Al and Fe–Al systems. Reassessment of the C15 Laves phase of the Fe–Zr system has been done to obtain a better description of the phases in the ternary system. The solution phases, including liquid, αα-Fe, γγ-Fe, αα-Zr, ββ-Zr and γγ-Al, were modelled as substitutional solutions, while the new ternary phases (τ1τ1, τ2τ2 and τ3τ3) were modelled as linear and stoichiometric compounds, respectively. The C14 and C15 Laves phases have been assessed using a two-sublattice model. Any ternary solubility of the other binary phases was not taken into account in the ternary assessment. The liquidus projection and several isothermal sections were calculated, and they agreed reasonably well with the reported experimental data.