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 Tb₂Fe₁₄B, TbFe₄B₄, Tb₅Fe₂B₆, Tb₃FeB₇ and TbFeB₄ 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 TbFe₂B₂ was not detected in this work.