Isothermal section of the Er–Co–Nd ternary system at 773 K

The isothermal section of the phase diagram of the Er–Co–Nd ternary system at 773 K was investigated by means of X-ray powder diffraction, differential thermal analysis, scanning electron microscopy with energy dispersive analysis and optical microscopy. The isothermal section consists of 16 single-phase regions, 25 two-phase regions, and 10 three-phase regions. The maximum solid solubility of Er in the compounds Co5Nd, Co19Nd5 and Co17Nd2 are about 10, 11 and 2 at.% Er, respectively. The maximum solid solubility of Nd in the compound Co17Er2 is about 3 at.% Nd. No solubility of Er in Co3Nd4 or Co2Nd5 was observed at 773 K. No solubility of Nd in Co3Er4 or Co7Er12 was observed at 773 K. Four pairs of corresponding compounds in the Nd–Co and Er–Co systems, i.e., Nd2Co7 and Er2Co7, NdCo3 and ErCo3, NdCo2 and ErCo2, Nd3Co and Er3Co form a continuous series of solid solutions, respectively. The binary compounds Co3Nd2, Co1.7Nd2 and ErCo5 were not observed at 773 K. No new ternary compound was found in all ternary alloy samples.