双主相(Ce,R)-Fe-B烧结磁体的核壳结构

Core-Shell Structured (Ce,R)-Fe-B Sintered Magnet Prepared by Binary Main Phase Method

研究了铈基双主相烧结磁体的磁性能和微结构,重点对双主相磁体不均匀的元素分布及微结构特征进行观察分析。研究表明:在双主相磁体的烧结及热处理过程中,稀土元素在两种主相晶粒之间发生了互扩散,形成了两种典型的核-壳结构晶粒,它们具有成分接近的"壳"和成分明显不同的"核"。双主相磁体中的这种核-壳结构,类似于"晶界扩散"Nd-Fe-B磁体的核-壳结构。在此基础上,对双主相(Ce, R)-Fe-B磁体的矫顽力增强机制和反磁化行为进行了解释。

The magnetic properties and microstructures of Ce-Fe-B-based sintered magnets prepared using binary main phase(BMP) method was investigated. The heterogeneous elemental distributions and microstructure characters of the BMP magnet were emphatically analyzed. Two types of core-shell structured grains are observed in the Ce-Fe-B-based BMP magnet;for the two typed grains, there are similar compositions in the shells, are obviously distinct compositions in the cores. It indicates that the inter-diffusions of rare earth atoms between the two types of main phase grains in the BMP magnet have happened during the sintering and annealing processes. The characteristic core-shell structures of the BMP magnets are similar to that of grain boundary diffused Nd-Fe-B sintered magnets. On this basis, the mechanism of coercivity enhancement and single phase-like demagnetization behavior of BMP magnets are well explained.