Effect of Tb/Y substitution on structural and magnetic properties of Fe-Nb-B-Tb type of high-coercive alloys

In the present work, we are focused on the influence of Tb/Y substitution on structural and magnetic properties of (Fe80Nb6B14)0.88Tb0.12-xYx (x = 0.02, 0.04, 0.06, 0.08, 0.1 and 0.12) nanocrystalline bulk alloys. The samples were prepared in the form of rods using the vacuum suction technique. The base alloy (x = 0) is characterized by an ultra-high coercivity and the Tb/Y substitution leads to an increase in magnetic saturation from 38 emu/g to 112 emu/g and the decrease in coercivity from 5.88 T to 0.05 T. However, optima of magnetic remanence and |BH|max parameter were observed. It was shown that the changes in magnetic properties are related to a partial replacement of Tb by Y in the unit cell of the Tb/Y2Fe14B phase. In the paper, the optimization of hard magnetic properties as well as its relation to phase composition and microstructure are widely discussed.