Variation of coercivity with Ce content in (Pr,Nd,Ce)2Fe14B sintered magnets

Abstract

The variation of coercivity with Ce content was investigated in (Pr,Nd)15-xCexFe77B8 (x=0∼10) sintered magnets. The coercivity of magnets largely decreases from 10.22 to 5.4 kOe with increasing x from 0 to 2. The coercivity rises to 7.68 kOe when x=3 and then decreases again with further increasing Ce content. However, both the magnetocrystalline anisotropy and Curie temperature decrease monotonically with increasing Ce content. EDS composition analysis shows that the Ce concentration in the Re2Fe14B main phase is higher than that in the nominal composition when x≤3, but becomes lower when x>3. These results indicate that Ce tends to be expelled from the main phase and segregates at or near the grain boundary regions if Pr-Nd is excessively substituted by Ce. The change of relative solubility of Ce in Re2Fe14B would lead to the change of distributions of Ce and Pr-Nd elements, and thus result in the change of anisotropy at the grain outer layer, contributing to the abnormal behavior of coercivity. These studied results are also expected to provide a guideline for optimizing the composition design of resource-saving permanent magnets.

Phase Formation and Magnetic Properties of La‐ and Ce‐Substituted (Nd1−2xRExPrx)2.28Fe13.58B1.14 Melt‐Spun Ribbons

“…Recently, the magnetic performances of Ce-and La-substituted Nd-Fe-B alloys were investigated. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] Lei et al, [6] Zhang et al [7] and Rehman et al [8,9] studied the phase composition, microstructure, and magnetic properties of Nd-Fe-B and Ce-Fe-B melt-spun ribbons with different doping metals such as La, Ta, and Ge. Zhu et al [10] reported that (Nd 1Àx Ce x ) 30 Fe bal B magnets prepared by the double main-phase alloy method show good magnetic properties.…”