Experimental determination and thermodynamic calculation of phase equilibria in the Ce-Fe-B ternary system

In this work, the phase equilibria of the Ce-Fe-B ternary system were investigated experimentally by using the equilibrated alloy method with electron probe microanalysis (EPMA) with wavelength-dispersive spectrometer (WDS), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) and X-ray powder diffraction (XRD). The experimental results revealed that three ternary intermetallic compounds Ce₂Fe₁₄B (τ₁) with the Nd₂Fe₁₄B-type structure and space group P4₂/mnm, Ce_1.1Fe₄B₄ (τ₂) with the Nd_l+εFe₄B₄-type structure and space group P4₂/n, and Ce₅Fe₂B₆ (τ₃) with the Pr₅Co₂B₆-type structure and space group $R\bar{3}m$ were confirmed, and two isothermal sections of the Ce-Fe-B ternary system at 673 K and 873 K were determined. Furthermore, based on the experimental results measured in this work and reported in the literature, thermodynamic calculation of the Ce-Fe-B ternary system was performed using the CALPHAD method in combination with the previous assessments of the Ce-Fe, Ce-B and Fe-B binary systems. The calculated isothermal sections, vertical sections and liquidus projection in the Ce-Fe-B ternary system show good agreement with the experimental results. It indicates that the self-consistent thermodynamic parameters of this ternary system were obtained in this work. This research provides a solid foundation for establishing a thermodynamic database of the multi-component Nd-Fe-B-based alloy systems, and then designing novel Nd-Fe-B permanent magnets containing high-abundant rare earth elements.