Experimental Determination of Phase Equilibria in the Ce-Co-Zr Ternary System

Abstract

The phase equilibria of the Ce-Co-Zr ternary system at 873 and 1073 K were determined for the first time by using equilibrated alloys in combination with scanning electron microscopy with energy dispersive spectroscopy and x-ray diffraction. No stable ternary intermetallic compounds were detected in the Ce-Co-Zr ternary system. Due to the partial substitution of Ce by Zr, the metastable binary intermetallic compound CeCo₇ with a solubility of 3.3 at.% Zr is stabilized at 873 K. The experimental results demonstrate that the maximum solubilities of Zr in the intermetallic compounds Ce₂Co₁₇, CeCo₅, Ce₅Co₁₉, Ce₂Co₇, CeCo₃, and CeCo₂ at 873 K are 4.3, 2.6, 2.4, 9.0, 17.9, 3.5 at.%, respectively, while the maximum solubilities of Ce in the intermetallic compounds Co₂₃Zr₆, Co₂Zr, and CoZr₂ are 6.7, 1.7, and 2.3 at.%. Meanwhile, the maximum solubilities of Zr in Ce₂Co₁₇, CeCo₅, Ce₅Co₁₉, Ce₂Co₇, CeCo₃ and CeCo₂ at 1073 K were measured to be 4.0, 7.5, 1.9, 6.8, 17.1, and 9.1 at.%, respectively, while the maximum solubilities of Ce in the intermetallic compounds Co₂₃Zr₆ and Co₂Zr were determined to be 7.0 and 4.5 at.%, respectively. Finally, the isothermal sections of the Ce-Co-Zr ternary system at 873 and 1073 K were established in this work.