Experimental determination of the equilibrium relationship of Fe–Pd–Pr ternary system at 773 K

• At 773 K, the homogeneity ranges of FePd and FePd3 have been determined.
• The 773 K isothermal section of the Fe–Pd–Pr was confirmed.
• A new ternary compound Pr6Fe13Pd was discovered.

The solid-state phase equilibria in the Fe–Pd–Pr ternary system at 773 K were investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), differential scanning calorimetry (DSC) and energy dispersion spectroscopy (EDS) techniques. It is found that the 773 K isothermal section consists of 14 single-phase regions, 26 two-phase regions, 13 three-phase regions. At 773 K, it is observed that the highest solubility of Pr in FePd and FePd3 are 1.4 and 1.3 at.% Pr, respectively. The solid solubility of Fe in Pd5Pr, Pd3Pr, Pd2Pr, Pd3Pr2, Pd4Pr3, PdPr, Pd3Pr7, and that of Pd in Fe17Pr2 are very little and less than 1 at.%. In this work, at 773 K, the homogeneity ranges of phases FePd and FePd3 in the Fe–Pd binary system have been determined to be 49.6–61.1 at.% Pd for FePd and 62.54–80.55 at.% Pd for FePd3, respectively. A new ternary compound Pr6Fe13Pd with space group I4/mcm, a = 0.80900 (7) and c = 2.24401 (4) nm was discovered.