Solid-state phase equilibria in the Co-Pt-Dy ternary system at 1173Â K

The solid-state phase equilibria in the Co-Pt-Dy ternary system at 1173 K (Dy ≤ 70%) were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersion spectroscopy (EDS) techniques. The 1173 K isothermal section consists of 14 single-phase regions, 24 two-phase regions, 10 three-phase regions and 1 four-phase region. At 1173 K, we have observed that the maximum solubility of Dy in α-(Co, Pt) is below 1.5 at.% Dy. The maximum solid solubility of Pt in Co17Dy2 is below 1 at.% Pt, whereas in Co7Dy2, Co3Dy and Co2Dy is about 1, 1 and 1.5 at.% Pt, respectively. The maximum solid solubility of Co in DyPt5, DyPt3, Dy3Pt4, DyPt, Dy5Pt4, Dy5Pt3, Dy2Pt and Dy3Pt is below 1 at.% Co, with uniquely being 19 at.% Co in DyPt2. In this work, one four-phase region including α-(Co, Pt), DyPt, DyPt2, and Dy3Pt4 phases was found. Co5Dy and any new ternary compounds were not observed.