过量Ce配比提升快淬Ce-Fe-B磁性能的机制研究

Mechanism of Magnetic Properties Enhancement by Increasing Ce Content in Ce-Fe-B Ribbons

Nd-Fe-B基永磁材料的广泛应用消耗了大量资源紧缺的Pr,Nd,Dy,而高丰度稀土元素Ce积压严重,近年来,发展含Ce的稀土永磁材料成为国家战略目标。但是Ce2Fe14B的内禀磁性能较差,还难以达到应用要求。在本文中,基于快淬+退火工艺制备了不同Ce含量的CexFe14B(x=2.0,2.2,2.4,2.6,2.8,3.0)合金,发现配比过量的Ce的可较大幅度提升合金的磁性能。选取退火态合金作对比,进一步研究其磁性能提升的机制,发现配比过量的Ce会导致出现CeFe2软磁相,CeFe2软磁相和Ce2Fe14B硬磁相之间的交换耦合作用可使快淬磁粉的剩磁Br和最大磁能积(BH)max得到提升;正成分的Ce2Fe14B在快淬条件下形成了TbCu7型结构的亚稳相,而配比过量的Ce可有效抑制TbCu7结构的形成,这有利于形成细小均匀的晶粒组织,同时使晶界锐化,晶界的钉扎作用加强使材料的矫顽力机制由形核机制转变为钉扎机制,从而使合金矫顽力也得到提高。

The resources of Nd,Pr and Dy were consumed excessively due to the widespread application of Nd-Fe-B based permanent magnets.Meanwhile,the rare earth elements La and Ce with abundant reserves were overstocked.In recent years,the development of rare earth permanent magnetic materials containing Ce became the national strategic goals.However,the Ce2Fe14B with poor intrinsic magnetic properties was difficult to meet the application requirements.CexFe14B(x=2.0,2.2,2.4,2.6,2.8,3.0)alloys with varied Ce content were prepared by melt spinning technique and annealing process,and the magnetic properties of Ce-Fe-B were enhanced by increasing Ce content.The as-annealed ribbons was selected for comparison and the mechanism of magnetic properties enhancement was studied,it was found that the CeFe2 soft magnetic phase were formed in alloys with excessive Ce,the exchange coupling interaction between CeFe2 soft magnetic phase and Ce2Fe14B hard magnetic phase could improve remanence(Br)and maximum energy product((BH)max).The TbCu7 metastable phase was formed in Ce2Fe14B as-quenched ribbons,but the formation of TbCu7 was suppressed by adding excessive Ce,which was beneficial to microstructure with uniform and small grain size,and the grain boundary was sharpened simultaneously.Because of the strengthened pining effect of grain boundary,the mechanism of coercivity turned from nucleation to pining with increasing Ce content,which was benefit to the enhancement of coercivity.