The isothermal section of the Gd–Dy–Co ternary system at 800 K

The isothermal section of the phase diagram of the Gd–Dy–Co ternary system at 800 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 this section consists of 9 single-phase regions and 9 two-phase regions, and 1 three-phase region. The compounds Gd2Co17 and Dy2Co17, Gd2Co7 and Dy2Co7, GdCo3 and DyCo3, GdCo2 and DyCo2, Gd12Co7 and Dy12Co7, Gd3Co and Dy3Co form a continuous series of solid solutions. In addition, the single phases α-Gd and α-Dy also form a continuous series of solid solution. The maximum solid solubility of Dy in Gd4Co3 is about 10.8 at.%. The binary compounds Dy4Co3, GdCo5 and DyCo5 were not observed at 800 K. No ternary compound was found.