Solid state phase equilibria in the Fe-Pt-Dy ternary system at 900 °C

The solid state phase equilibria in the Fe-Pt-Dy ternary system at 900 °C (Dy ≤ 75 at.%) were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersion spectroscopy (EDS) techniques. It is found that the 900 °C isothermal section consists of 18 single-phase regions, 33 two-phase regions and 16 three-phase regions. At 900 °C, it is observed that the maximum solid solubility of Pt in Fe2Dy and α-(Fe, Dy) is 5 at.% Pt and 3 at.% Pt, respectively. The binary phase Fe5Dy was not observed. The existence of DyPt5, DyPt3, DyPt2, Dy3Pt4, DyPt, Dy5Pt4, Dy5Pt3, Dy2Pt and Dy3Pt compounds is confirmed and the maximum solubility of Fe in them is below 1 at.% Fe; the maximum solubility of Dy in α-(Fe, Pt), γ-(Fe, Pt), FePt, FePt3 and (Pt, Fe) (the solid solution of Fe in Pt) is 3 at.% Dy, 2 at.% Dy, 2 at.% Dy, 1.5 at.% Dy and 1.5 at.% Dy, respectively.