烧结Nd-Fe-B中的热力学影响

在烧结Nd-Fe-B中，各种相的形成，添加元素原子的替代、对磁体的微结构和性能的影响以 及大多数工艺与热力学都有密切联系.Al，Cu，Ga，Sn，Zn等与B均具有正的混合焓，在主相 中的浓度都很低，与富 Nd相反应改善磁体的微结构. Zi,Ti，Nb，W，Mo，V等与Nd有很大的 正的混合焓，与B具有很大的负的混合焓，能优化磁体的微结构和稀释磁体.参考热力学，系 统讨论了各种常用添加元素对烧结Nd-Fe-B的微结构、性能和制造工艺的影响. 关键词： Nd-Fe-B永磁体 混合焓 烧结

Thermodynamic effects on the sintered Nd-Fe-B magnets

In the sintered Nd-Fe-B magnets, the forming of various phases, substitution and preference of additive atoms, microstructure and properties, and, most of proce ssing have a close relationship to the thermodynamics. The Al, Cu, Ga, Sn, Zn ha ve positive heat of mixing with the B, the solubility of them in the main phase is small, they react with Nd in the grain boundary and modifying the microstruct ure of the magnets. The Zr, Ti, Nb, W, Mo, V, Cr have large positive heat of mix ing with Nd while have large negative heat of mixing with the B, they can modify the microstructure as well as dilute the magnets. The effects of the common add itional elements on the microstructure, properties and the processes of Nd-Fe-B magnets are discussed in this work by referring the heat of mixing and the binar y diagrams.