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

Effects of orientation and interaction of grains on coercivity for 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” Gaussian function is applie...

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Bibliographic Details
Published in:Science China. Mathematics Vol. 42; no. 6; pp. 653 - 659
Main Authors: Gao, Ruwei, Li, Wei, Zhang, Jiancheng, Wu, Liangxue, Yu, Xiaojun
Format: Journal Article
Language:English
Published: Heidelberg Springer Nature B.V 01-06-1999
Subjects:
Alignment
Coercivity
Coupling
Field theory
Grain boundaries
Grain size
Permanent magnets
Sintering
Online Access:Get full text
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Summary: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.
ISSN:1674-7283
1869-1862
DOI:10.1007/BF02880084