Experimental determination of phase diagram at 450 °C in the Zn–Fe–Al ternary system

Phase equilibria in multi-phase Zn–Fe–Al alloys were experimentally measured using a field-emission electron probe micro-analyzer for alloy samples, and a precise iso-thermal phase diagram at 450 °C in the entire composition range of the Zn–Fe–Al ternary system, except for the Fe-rich corner, was determined. The ternary solubility ranges of the Γ-Fe₄Zn₉, Γ₁-Fe_21.2Zn_80.8, δ_1k-FeZn₇, and ζ-FeZn₁₃ on the Fe–Zn side and of the ζ-FeAl₂, η-Fe₂Al₅, and θ-Fe₄Al₁₃ on the Fe–Al side were consistent with the latest corresponding binary data, whereas no δ_1p-Fe₁₃Zn₁₂₆ phase was detected. The single-phase region of the Γ₂-Fe₈Zn₈₇Al₄ ternary intermetallic compound phase is significantly narrower than that reported in the previous studies. The solubility of Fe in the liquid phase increased consistently and continuously from the value in the Zn–Fe binary system (0.6 at.%) up to 1.2 at.% at 31 at.% Al with increasing Al content. In the Al-rich portion of the phase diagram at 450 °C, the Fe(Al, Zn)₆ intermetallic compound phase was newly discovered, and confirmed to be an isomorph extended from the FeAl₆ phase which is metastable in the Fe–Al binary system.