Experimental study and thermodynamic calculation of the Sm-Co-Fe system

In this work, phase equilibria of the Sm-Co-Fe ternary system at 1073 K, 1273 K and 1473 K were measured using scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) and X-ray diffractometer (XRD). No ternary intermetallic compounds were observed. The continuous solid solution phases Sm2(Co, Fe)17, Sm(Co, Fe)3 and Sm(Co, Fe)2 were formed from the respective Sm–Co and Sm–Fe binary intermetallic compounds due to the same phase structures. The intermetallic compound SmCo5 with a certain solubility of Fe was confirmed to be stable at 1073 K. The solubility of Fe in SmCo5, Sm5Co19 and Sm2Co7 intermetallic compounds was determined. Based on the experimental results determined in this work and reported in the literature, thermodynamic calculation of the Sm-Co-Fe ternary system was performed using the CALPHAD method in the combination with the previous assessments of three Sm–Co, Sm–Fe and Co–Fe binary systems. The liquidus projection, isothermal sections and vertical sections of this ternary system were calculated. The good agreement between the calculated results and the experimental results was achieved.