Experimental investigation and thermodynamic re-assessment of the Mn–Gd binary system

In this work, 13 Mn–Gd alloys prepared by arc-melting method were investigated experimentally by means of differential thermal analysis. The temperatures of the invariant reactions and liquidus in the Mn–Gd binary system were determined according to the measured thermal analysis curves. One key as-cast Mn 70 Gd 30 alloy was examined using differential thermal analysis and scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy to confirm the type of the invariant reaction (L + Mn 23 Gd 6 ↔ Mn 2 Gd). Based on the critical review of the available experimental data measured in the present work and in the reported literature, the Mn–Gd binary system was assessed thermodynamically using the CALPHAD method. The solid solution phases including liquid, α-Mn, β-Mn, γ-Mn, δ-Mn, α-Gd and β-Gd are modeled by the substitutional solution model, while the intermetallic compounds such as GdMn 2 , Gd 6 Mn 23 and GdMn 12 are treated as the stoichiometric compounds. A set of self-consistent thermodynamic parameters obtained finally to describe the Gibbs energies of various phases in the Mn–Gd binary system can be used to reproduce well phase equilibria and thermodynamic data.