摘要
采用双合金法,即将2种粉末混合压制成型制备烧结永磁体可提高磁体磁性能。本实验将Nd_(13)Fe_(81)B_(6)和TbH_(x)粉末混合制成烧结磁体,研究Tb元素扩散分布以及其对磁性能的影响。Nd_(13)Fe_(81)B_(6)磁体矫顽力为358.2 kA/m,当TbH_(x)混合量为3%(质量分数,下同)时,烧结磁体的矫顽力增加至1592 kA/m。扫描电镜和元素面分布谱表明,Tb元素更容易扩散进入Nd_(2)Fe_(14)B主相而不是富集在晶间富稀土相。Tb元素进入主相会替代Nd形成具有更高各向异性场的(Nd, Tb)-Fe-B表层,这样在反磁化过程中晶粒表层磁畴壁的形核场会增加,因此矫顽力增加程度显著。但是,TbH_(x)混合量超过5%时,磁体中更多Tb原子从晶粒表层扩散入Nd_(2)Fe_(14)B相晶粒内部,这样晶粒表层反磁化形核场的提高程度会减弱,因而磁体矫顽力增加幅度降低。本研究说明要进一步提高双合金Nd-Fe-B磁体磁性能需控制元素扩散并优化磁体的元素分布。
The magnetic properties could be improved in sintered magnets prepared by the dual-alloy method via mixing two different types of powders followed by pressing and sintering. In the present paper, the sintered magnets were prepared by mixing Nd_(13)Fe_(81)B_(6) with TbH_(x) powders to investigate the effect of Tb element diffusion on the magnetic properties. The coercivity is 358.2 kA/m in Nd_(13)Fe_(81)B_(6) magnets, and it increases to 1592 kA/m with 3 wt% TbH_(x) addition in the sintered magnets. Owing to the thermodynamical origin Tb atoms prefer to diffuse into the grain interior of Nd_(2)Fe_(14)B phase in the sintering rather than aggregate in the intergranular rare-earth-rich phase. Tb atoms could substitute for Nd and form(Nd, Tb)-Fe-B shell layer with higher anisotropy in the main phase, and so the nucleation field of reversed domain wall is improved at grain outer-layer, leading to the significant increase of coercivity. However, for an increase in the amount of TbH_(x) addition more than 5 wt%, more amount of Tb atoms diffuse into the grain interior of Nd_(2)Fe_(14)B phase in the magnets. The enhancement effect of improving the nucleation field is weakened at grain outer-layer, resulting in the reduction of the increase amplitude of coercivity. It shows that regulating the atomic diffusion and optimizing the elemental distribution are necessary to further improve the magnetic properties in Nd-Fe-B magnets prepared by the dual-alloy method.
作者
秦渊
马斌杰
李柱柏
Qin Yuan;Ma Binjie;Li Zhubai(Key Laboratory of Integrated Exploitation of Bayan Obo Multi-Metal Resources,School of Science,Inner Mongolia University of Science and Technology,Baotou 014010,China)
出处
《稀有金属材料与工程》
SCIE
EI
CAS
CSCD
北大核心
2021年第4期1378-1383,共6页
Rare Metal Materials and Engineering
基金
国家自然科学基金(51861030)。
