Magnetic properties and element distribution in sintered (Nd,Pr)-Fe-B/Tb-Fe-B composite magnets

Abstract (Nd,Pr)-Fe-B powders were mixed with Tb 13 Fe 81 B 6 powders to prepare sintered (Nd,Pr,Tb)-Fe-B magnetic materials. A little amount addition of Tb 13 Fe 81 B 6 powders leads to a faster increase of coercivity, and the coercivity increases from 14.95 kOe to 18.93 kOe at the mass ratio 9.7:0.3 of (Nd,Pr)-Fe-B and Tb 13 Fe 81 B 6 . For the mass ratio of Tb 13 Fe 81 B 6 more than 0.3 the coercivity increases nearly linearly. Both the remanence and the maximum energy product decrease slightly for a little amount addition of Tb 13 Fe 81 B 6 . The investigation by energy dispersive spectrometer shows that though there are dual main phases in the sintered magnets, the chemical compositions of main phase are much different from those of the master alloys due to the atomic diffusion. It is expected to improve the coercivity more largely by optimizing the element distribution in the sintered composite magnets.