An investigation of the Gd-Fe-Cr phase diagram: Phase equilibria at 800 °C

Abstract

The phase equilibria of Gd-Fe-Cr system were investigated at 800 °C by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS). The isothermal section of the phase diagram consisted of eight single-phase regions, eight two-phase regions and seven three-phase regions. The binary compounds GdFe2, GdFe3, Gd2Fe17, σ(FeCr) and the ternary compound GdFe10Cr2 were confirmed. Conversely, the binary compound Gd6Fe23 was unstable at the level of 800 °C. The maximum solid solubilities of Cr in GdFe2 and Gd2Fe17 were about 11.7 and 13.2 at. % Cr respectively. The compound GdFe12−xCrx with the ThMn12-type structure (space group I4/mmm) has a broad solubility ranging from 15.4 to 23.1 at. % Cr.