Ce、La添加对DyCo晶界扩散烧结Nd-Fe-B磁体性能的影响

Effect of Ce and La addition on properties of DyCo grain boundary diffusion sintered Nd-Fe-B magnets

为了有效利用高丰度稀土,在重稀土扩散源Dy_(60)Co_(40)中添加Ce、La以取代Dy。研究了不同的Ce、La添加量对Dy_(60)Co_(40)晶界扩散烧结Nd-Fe-B磁体性能的影响。结果表明:Dy_(30)Ce_(30)Co_(40)、Dy_(30)(Ce_(0.4)La_(0.6))_(30)Co_(40)晶界扩散均能大幅提升Nd-Fe-B磁体的矫顽力,分别为1509和1527 kA/m,相比原始Nd-Fe-B磁体的矫顽力分别提高了31.7%和33.2%,且剩磁和最大磁能积下降不明显。微观组织研究表明,Ce主要分布在晶界相中形成富Ce相,不利于Dy的扩散;而La的添加限制了Ce进入主相晶粒,促进了Dy的扩散,从而进一步提高了磁体的矫顽力。热稳定性研究发现,Ce、La的添加均能提高磁体的热稳定性,但是其提升效果均没有Dy_(60)Co_(40)扩散磁体明显,这与形成了低磁晶各向异性场的Ce_(2)Fe_(14)B和La_(2)Fe_(14)B相有关。

In order to effectively utilize high abundance rare earths,Ce and La were added to the heavy rare earth diffusion source Dy_(60)Co_(40)to replace Dy.The effect of different Ce and La additions on properties of Dy_(60)Co_(40)grain boundary diffusion sintered Nd-Fe-B magnets was studied.The results show that both Dy_(30)Ce_(30)Co_(40)and Dy_(30)(Ce_(0.4)La_(0.6))_(30)Co_(40)grain boundary diffusion can significantly enhance the coercivity of Nd-Fe-B magnets,with values of 1509 and 1527 kA/m,respectively.Compared with the original Nd-Fe-B magnet,the coercivity is increased by 31.7%and 33.2%,respectively,and the decrease in remanence and maximum magnetic energy product is not significant.The microstructure study shows that Ce is mainly distributed in the grain boundary phase to form a Ce-rich phase,which is not conducive to the diffusion of Dy.The addition of La restricts the entry of Ce into the main phase grains,promotes the diffusion of Dy,and further enhances the coercivity of the magnet.The thermal stability study found that the addition of Ce and La can improve the thermal stability of the magnet,but the improvement effect is not as obvious as that of the Dy_(60)Co_(40)diffusion magnet,which is related to the Ce_(2)Fe_(14)B and La_(2)Fe_(14)B phases that form a low magnetocrystalline anisotropy field.