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

摘要

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 Co_5Nd, Co_(19)Nd_5 and Co_(17)Nd_2 are about 10,11 and 2 at.% Er, respectively. The maximum solid solubility of Nd in the compound Co_(17)Er_2 is about 3 at.% Nd. No solubility of Er in Co_3Nd_4 or Co_2Nd_5 was observed at 773 K. No solubility of Nd in Co_3Er_4 or Co_7Er_(12) was observed at 773 K. Four pairs of corresponding compounds in the Nd-Co and Er-Co systems, i.e., Nd_2Co_7 and Er_2Co_7, NdCo_3 and ErCo_3, NdCo_2 and ErCo_2, Nd_3Co and Er_3Co form a continuous series of solid solutions, respectively. The binary compounds Co_3Nd_2, Co_(1.7)Nd_2 and ErCo_5 were not observed at 773 K. No new ternary compound was found in all ternary alloy samples.