The 1073 K isothermal section of the Gd-Fe-Cu system

A series of Gd-Fe-Cu alloys was prepared to determine the 1073 K isothermal section of the Gd-Fe-Cu system through the use of the Scanning Electron Microscopy-Energy Dispersive X-ray spectrometry (SEM-EDS) and the X-ray Powder Diffraction (XRD) techniques. Twelve single phase regions, eleven two-phase regions, and ten three-phase regions, as well as two liquid areas were experimentally identified at 1073 K. The phase diagram at this temperature is characterized by the formation of a new ternary compound Gd6Fe20.5Cu2.5 labelled A and eight binary compounds namely Gd2Fe17, GdFe3, GdFe2, GdCu, GdCu2, GdCu5, Gd0.8Cu5.4 and Hcp (GdCu). However, unlike previous studies that showed the compound Gd6Fe23 is stable at 1073 K, we demonstrated that it is not, and becomes stable at 1173 K. Among the eight formed binary compounds, six have extensions into the ternary system: MgCu2-type GdFe2−xCux (x = 0–0.2), Th2Zn17-type Gd2Fe17−xCux (x = 0–1.5), CsCl-type GdCu1−xFex (x = 0–0.5), KHg2-type GdCu2−xFex (x = 0–0.6), CaCu5-type GdCu5−xFex (x = 0–0.2) and Tb0.78Cu5.44-type Gd0.8Cu5.4−xFex (x = 0–0.2). •Binary, pseudo-binary and ternary of Gd-Fe-Gu intermetallics alloys have synthesized.•A systematic XRD Rietveld refinement and SEM/EDS have been used to analyze those compounds.•New isothermal section at 800 °C of Gd-Fe-Cu system was established. Keywords: intermetallic; phase diagram; rare earth.