Experimental determination of phase equilibria in the Sm-Co-Zr ternary system

Abstract

In this work, phase equilibria of the Sm-Co-Zr ternary system at 1073 K and 773 K were investigated using diffusion couple method and equilibrium alloy method with scanning electron microscopy with energy dispersive spectrometry (SEM-EDS), X-ray diffraction (XRD) and electron probe microanalysis (EPMA). No stable ternary intermetallic compounds in the Sm-Co-Zr ternary system were found at 1073 K and 773 K. The solubilities of Zr in intermetallic compounds SmCo2, SmCo3, Sm2Co7, Sm5Co19, SmCo5 and Sm2Co17 at 1073 K were determined to be 7.3 at.%, 18.6 at.%, 9.9 at.%, 5.1 at.%, 1.4 at.% and 4.9 at.%, respectively, while those of Zr in these intermetallic compounds at 773 K were measured to be 4.3 at.%, 17.4 at.%, 9.5 at.%, 1.9 at.%, 0.9 at.% and 5.6 at.%. Meanwhile, the solubility of Sm in Co23Zr6 was measured to be 6.5 at.% and 5.1 at.% at 1073 K and 773 K, respectively, while the solubility of Sm in other intermetallic compounds is very limited (less than 2 at.%). Isothermal sections of the Sm-Co-Zr ternary system at 1073 K and 773 K were constructed.