Isothermal section of Gd-Sm-Co ternary system at 773 K

The isothermal section of the phase diagram of the Gd-Sm-Co ternary system at 773 K was investigated by X-ray powder diffraction (XRD), differential thermal analysis (DTA)optical microscopy and scanning electron microscopy (SEM) techniques. The result shows that the isothermal section consists of 12 single-phase regions, 16 two-phase regions and 5 three-phase regions. Five pairs of corresponding compounds of Gd-Co and Sm-Co systems, i.e., Gd2Co17 and Sm2Co17, Gd2Co7 and Sm2Co7, GdCo3 and SmCo3, GdCo2 and SmCo2, Gd3Co and Sm3Co form continuous series of solid solutions. The maximum solid solubility of Sm in Gd4Co3 and Gd12Co7 were about 7.2 at.% and 47.8 at.% Sm, respectively. The maximum solid solubility of Gd in Sm5Co19 and Sm5Co2 were about 4.7 at.% and 7.6 at.% Gd, respectively. The binary compounds Sm9Co4, GdCo5 and SmCo5 were not observed at 773 K. No ternary compound was found.