Effects of orientation and interaction of grains on coercivity for sintered NdFeB magnets  

作　　者：高汝伟 李卫 张建成 吴良学 喻晓军 

出　　处：《Science China Mathematics》1999年第6期653-659,共7页中国科学：数学（英文版）

基　　金：Project supported by the National Natural Science Foundation of China (Grant No. 59571017)

摘　　要：The coercivity of NdFeB magnets is determined by the coercivity of individual grains and the interaction between the grains composed of the magnets. The coercivity of individual grains and the intergrain interaction depend on the degree of the grain alignment, “tanθ type” Gaussian function is applied to describing the degree of the grain alignment. According to different coercivity mechanisms, there are different formula on the coercivity and the angular dependence of coercivity. The interaction between grains can be classified as the long-range magnetostatic interaction and the exchange-coupling interaction of neighboring grains. For the sintered magnet, the grain size is large and the grain boundaries are mostly separated by the non-magnetic phase. So, the long-range magnetostatic interaction is much stronger than the exchange coupling interaction and it makes the coercivity of the magnet composed of misaligned grains be bigger than that of the magnet composed of ideally aligned grains. The effects of coercivity of individual grains and the intergrain interactions are taken into account, and the starting field theory is in agreement with the experimental result for the coercivity of sintered NdFeB magnets.The coercivity of NdFeB magnets is determined by the coercivity of individual grains and the interaction between the grains composed of the magnets. The coercivity of individual grains and the intergrain interaction depend on the degree of the grain alignment. 'tanθ type' Ganssian function is applied to describing the degree of the grain alignment. According to different coercivity mechanisms, there are different formula on the coercivity and the angular dependence of coercivity. The interaction between grains can be classified as the long-range magnetostatic interaction and the exchange-coupling interaction of neighboring grains. For the sintered magnet, the grain size is large and the grain boundaries are mostly separated by the non-magnetic phase. So, the long-range magnetostatic interaction is much stronger than the exchange coupling interaction and it makes the coercivity of the magnet composed of misaligned grains be bigger than that of the magnet composed of ideally aligned grains. The effects

关 键 词：NDFEB sintermagnets grain alignment EXCHANGE-COUPLING INTERACTION LONG-RANGE MAGNETOSTATIC INTERACTION COERCIVITY starting field theory. 

分 类 号：O482.5[理学—固体物理]