Solid-state phase equilibria in the Er-Nd-Fe ternary system at 1073 K

Abstract The solid state phase equilibria in the ternary Er-Nd-Fe system at 1073 K in all the composition ranges were investigated using the experimental results of the X-ray powder diffraction analysis (XRD) as well as those obtained from the Scanning electron microscopy (SEM) equipped with Energy dispersive spectroscopy (EDS). The binary systems Er–Fe, Er–Nd and Nd-Fe were investigated prior to the study of the ternary one. Six binary compounds were identified to exist at this isothermal sectionss at 1073 K namely: ErFe 2 ( F d 3 ¯ m -MgCu 2 structure type), ErFe 3 ( R 3 ¯ m -PuNi 3 structure type), Er 6 Fe 23 (Fm-3m-Th 6 Mn 23 structure type), Er 2 Fe 17 ( P 6 3 / m m c -Th 2 Ni 17 structure type), Nd 2 Fe 17 ( R 3 ¯ m -Th 2 Zn 17 structure type), and δ-NdEr ( R 3 ¯ m -Sm structure type). No new ternary compounds were found in all investigated ternary alloy samples. The phase relations are governed by seven three-phase regions, sixteen two-phase regions and nine single-phase regions, as well as a small liquid area in the Nd-rich region. At 1073 K, we have observed that the highest solubility of Nd in ErFe 2 is about 16.6 at. % Nd, while the Er 1 − x NdxFe 3 solid solution based on binary ErFe 3 extends up to 7.5 at. % Nd. The XRD and the SEM/EDS analyses show that there is no miscibility of Nd in Er 6 Fe 23 . The pair of the binary compounds Er 2 Fe 17 and Nd 2 Fe 17 extend through the ternary system parallel to the Nd-Er edge. The maximum homogeneity range of the Er 2 − x NdxFe 17 solid solution reaches 5.3 at. % Nd, while that of the Nd 2 − x ErxFe 17 solid solution is about 1.6 at. % Er. In the Er-Nd binary system, the maximum solid solubility of Nd in Er is about 38.4 at. % Nd, and the solubility limit of Er in Nd is about 29.8 at. % Er.