Phase equilibria of the Tb-Fe-B system at 1000, 900 and 800 °C

Phase equilibria of the Tb-Fe-B system were investigated at 1000, 900 and 800 °C using X-ray diffraction (XRD) and electron probe microanalysis (EPMA) on annealed alloys with a B content ≤50 at.%. Isothermal sections at 1000, 900 and 800 °C were then proposed, revealing the similar phase equilibria except for the phase regions containing liquid, which originates from the binary Fe-Tb system at 900 and 1000 °C. Five ternary compounds of Tb 2 Fe 14 B, TbFe 4 B 4 , Tb 5 Fe 2 B 6 , Tb 3 FeB 7 and TbFeB 4 were observed to be stoichiometric and the solubilities of Tb in Fe-B, Fe in Tb-B and B in Tb-Fe binary phases were measured to be negligible. Additionally, the ternary compound TbFe 2 B 2 was not detected in this work. • Tb 2 Fe 14 B, TbFe 4 B 4 , Tb 5 Fe 2 B 6 , Tb 3 FeB 7 and TbFeB 4 were observed at 1000, 900 and 800 °C. • The ternary compounds were stoichiometric at 1000, 900 and 800 °C. • The ternary compound TbFe 2 B 2 was not detected at 1000, 900 and 800 °C. • 4. Solubilities of Tb in Fe-B, Fe in Tb-B and B in Tb-Fe binary phases were negligible.