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 i11ustrate the agglomeration phenomenon. We believe that the generai existence of misaiignment gains in the magnetic force images of the sintered Nd-Fe-B magnet fabricated by die pressing with 1500kAm^-1 aiignlng field is a confirmation of the magnetic agglomeration.     

液相烧结对Nd-Fe-B粉末压坯及磁体取向度的影响

XBD，SEM及MFM观察表明，Nd-Fe-B粉末压坯在液相烧结过程中同时存在两种影响主相晶粒取向度的机制：烧结过程中大颗粒吞并吸附在其表面的取向不良的小晶粒并择优长大，使磁体的取向度提高；在液相烧结过程中，被液相所包围的主相晶粒的自由转动，造成磁体的取向度降低。对于取向度较低的DP生坯，烧结中影响Nd-Fe-B磁体取向度的前一种机制是主导的；而对于取向度较高的振动RIP生坯，烧结过程中后一种机制起主导作用。     

封面故事

磁场是自然界中最高效的能量转换媒体.以烧结Nd-Fe-B及烧结2-17型Sm-Co为代表的稀土永磁体具有极高的磁能积,因而用它们制作的永磁器件能产生强大的磁场.因此,稀土永磁体产品特别是烧结Nd-Fe-B永磁体,不仅支撑着当代手机、电脑