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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