The isothermal section of the phase diagram of Gd-Mn-Ga (≤50 at.%Ga) ternary system at 873K

Abstract

The phase diagram of the Gd-Mn-Ga ternary system is a very important tool for the exploration and development of rare earth Heusler alloys with excellent physical properties, such as magnetic properties, half-metallic properties, ferromagnetic shape memory effect, magnetocaloric effect, ect. In this study, the alloy samples were prepared using a vacuum arc melting furnace, and the 873 K isothermal section of the Gd-Mn-Ga (≤50 at.%Ga) ternary alloy phase diagram was determined by using X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy spectrometry (EDS). The isothermal section consists of 22 single-phase regions, 44 two-phase regions, and 23 three-phase regions with the presence of 6 ternary compounds, GdMnGa, Gd₂MnGa₆, Gd₂Mn₁₅Ga₂, Gd₂Mn₁₁Ga₆, GdMn_0.56Ga_1.44, and GdMn_0.37Ga_1.63. The solid solubility ranges of Ga in β-Mn and Gd₂Mn₁₅Ga₂ are 5.0–18.1 at.%Ga and 10.5–25.0 at.% Ga. The maximum solid solubility of Ga in α-Mn, GdMn₁₂, and Gd₆Mn₂₃ are 2.0, 2.7, and 7.3 at.% Ga, respectively. The maximum solid solubility of Mn in GdGa₂ is determined to be 13.1 at.% Mn.