Experimental determination and thermodynamic assessment of the Dy-Fe-B system

The phase equilibria of the Fe-Dy-B system on the Fe-Dy side are crucial for the development of Nd-Dy-Fe-B permanent magnets. Alloys located on the Fe-Dy side were prepared and annealed at 1073 K and 1173 K for 60 days. The annealed samples were analyzed by electron probe microanalysis (EPMA) and X-ray diffraction (XRD). In this work, three ternary compounds τ₁, τ₃, and τ₄ were identified on the Fe-Dy side at 1073 K and 1173 K. The previously reported τ₂ phase was not observed in the present work. Nine three-phase regions were determined in the present study and the isothermal sections of the Dy-Fe-B system on the Dy-Fe side at 1073 K and 1173 K were constructed. Based on the experimental data, thermodynamic modeling of the system was performed using the CALculation of PHAse Diagrams (CALPHAD) method. The calculated results show good agreement with the experimental data.