Magnetic agglomeration among Nd-Fe-B particles and its influence on field aligning

There exists strong magnetic agglomeration among Nd-Fe-B particles. Due to this effect, an applied field even up to 1350kAm(-1) still can not make the loose Nd-Fe-B powders to reach saturated magnetization. SEM images of a little amount of Nd-Fe-B powders were used to illustrate the agglomeration phenomenon. We believe that the general existence of misalignment grains in the magnetic force images of the sintered Nd-Fe-B magnet fabricated by die pressing with 1500kAm(-1) aligning field is a confirmation of the magnetic agglomeration.