Solid-state phase equilibria in the Co–Pt–Pr ternary system at 1173 K

The solid-state phase equilibria in the Co–Pt–Pr ternary system at 1173 K (Pr ≤ 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 15 single-phase regions, 24 two-phase regions and 10 three-phase regions. At 1173 K, we have observed that the maximum solid solubility of Pt in Co 17Pr 2, Co 5Pr, Co 19Pr 5, Co 7Pr 2, Co 3Pr and Co 2Pr is below 1 at.% and the maximum solid solubility of Co in PrPt, Pr 3Pt 2 and Pr 7Pt 3 is also below 1 at.%, but the maximum solubility of Co in PrPt 5 and PrPt 2 is 15 and 7.5 at.%, respectively, and the homogeneity range for the PrPt 2 phase is between approximately 24.2% and 31.7 at.% Pr; the maximum solubility of Pr in α-(Co, Pt) is below 1.5 at.%. In this work, it is found that the phase Pr 3Pt 4 does not exist in the ternary system. No any new ternary compounds were observed.