Effects of Cerium on Permanent Magnetic Properties of Sintered Nd-Fe-B Magnets

publisher: William Chang
Time: 2017-10-08
Summary: CeFeB, the new generation of NdFeB
Cerium is a very special element in Lanthanide,originating from its mixed valence characteristics.

Ce exists in Ce 2 Fe 14 B as Ce 4 + ion. The lack of 4f electron leads Ce 4 + to make no contribution to magnetism. 

Small ion radius shrinks theFe-Fe distances and decreases the Curie temperature and saturation polarization of Ce 2 Fe 14 B. In addition,it is in favor ofCeFe 2 Laves phase instead of Ce-rich phase to magnetically decouple Ce 2 Fe 14 B grains. Sintered Ce-Fe-B magnet has very poor coercivity. 

Rapidly quenched isotropic (Ce,Nd)-Fe-B powder can realize reasonable H cJ for certain applications. Bydual-alloy or dual-main-phase techniques,using Ce-rich/Nd-lean alloy and Nd-rich/Ce-lean alloy as starting materials,sintered (Ce,Nd)-Fe-B magnet is commercialized with high ratio of performance to cost. The key point is to let Nd-rich phase decouple (Ce,Nd) 2 Fe 14 B grains. This article reviews the effects of Cerium on the intrinsic and extrinsic magnetic properties of Nd-Fe-B permancent magnets.

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