Effect of Ce on the Magnetic Properties and Microstructure of Sintered Didymium-Fe-B Magnets

In this paper, the influence of the substitution of didymium (Pr-Nd alloy, abbreviated to Di) with Ce on the microstructure and magnetic properties of sintered permanent magnet was investigated. A series of (Di
_1-x
Ce
_x
)
_27.5
Dy
₃
Al
_0.1
Cu
_0.1
Fe
_bal.
B
₁
(x = 0-0.56) magnets were fabricated by powder metallurgy route. The results indicated that essential magnetic properties, such as remanence and energy product, deteriorated by substituting Di with Ce. In general, the coercivity decreased with the increase of the content of Ce, whereas there was a sudden increase of coercivity when x = 0.24. Microstructural observations and phase analyses illustrated that grain boundary layers were thickened in magnets with x ≥ 0.24, which was attributed to the formation of CeFe
₂
phase.