High performance and exchange coupling in magnetization reversal of sintered (Nd,Dy)-Fe-B magnets
High performance and exchange coupling in magnetization reversal of sintered (Nd,Dy)-Fe-B magnets
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烧结 (Nd,Dy)-Fe-B 磁体磁化反转中的高性能和交换耦合
DOI：
10.1016/j.jallcom.2022.166944
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发表时间：
2022-08
影响因子：
6.2
通讯作者：
Suo Bai
中科院分区：
文献类型：
--
作者：
Zhu-bai Li;Zhen Zhang;Yuan-zhe Fu;Chao Wang;Lei Wei;Suo Bai
提高烧结 Nd-Fe-B 磁体的矫顽力会牺牲剩磁和磁能积。在这项工作中，它开发了一种制备复合（Nd，Dy）-Fe-B磁体的方法，以提高矫顽力，同时剩磁略有下降。通过在Nd-Fe-B粉末中添加Dy-Fe-B共混、压实、烧结制备了高性能(Nd,Dy)-Fe-B磁体。 Dy-Fe-B粉末的添加提高了烧结磁体的矫顽力。热激活研究表明，热激活波动场不服从矫顽力增大的规律。 (Nd,Dy)-Fe-B磁体中共存了Dy-Fe-B晶相晶粒，通过交换耦合增大了磁畴壁尺寸，减小了磁化反转时的波动场。部分Dy原子扩散到Nd2Fe14B晶相的晶粒外层，晶界结构可能得到优化，晶壳处的各向异性增大，因此磁畴壁尺寸会减小，导致涨落场增大。虽然它们的交换耦合和各向异性增加对磁畴壁尺寸和波动场的变化的影响相反，但它们有利于提高磁化反转时的成核场，并且烧结磁体的矫顽力显着增加。由于Dy-Fe-B粉末主要演化为RE2Fe14B晶体的主相而不是晶间相，因此铁磁相的质量分数没有明显下降。由于交换耦合效应、晶粒核壳形貌以及晶间相数量没有显着增加，烧结(Nd,Dy)-Fe-B复合磁体获得了46.6 MGOe的高磁能积和20.5 kOe的高矫顽力的高性能。
Improving the coercivity in sintered Nd-Fe-B magnets would sacrifice the remanence and the energy product. In this work it develops a method of preparing the composite (Nd,Dy)-Fe-B magnets to enhance the coercivity with a slighter decrease of remanence. The high performance (Nd,Dy)-Fe-B magnets were prepared via adding Dy-Fe-B into Nd-Fe-B powders in blending, followed by compacting and sintering. The addition of Dy-Fe-B powders gave rise to the enhancement of coercivity in the sintered magnets. The investigation of thermal activation indicates that the fluctuation field in thermal activation doesn’t obey the law of increasing with the coercivity. The grains of Dy-Fe-B crystal phase coexist in (Nd,Dy)-Fe-B magnets, which could increase the domain wall size by exchange coupling and decrease the fluctuation field in magnetization reversal. Some of Dy atoms diffuse into the grain outer-layer of Nd2Fe14B crystal phase, the grain boundary structure is probably optimized, the anisotropy increases at grain shell, and so the domain wall size would be reduced, leading to an increase of the fluctuation field. Though their effects of the exchange coupling and the anisotropy increasing are opposite on the changes of the domain wall size and fluctuation field, they are beneficial to improve the nucleation field in magnetization reversal, and the coercivity increases significantly in the sintered magnets. Since Dy-Fe-B powders mainly evolve into the main phase of RE2Fe14B crystal instead of the intergranular phase, the mass fraction of ferromagnetic phase doesn’t decrease evidently. Owing to the exchange coupling effect, the core-shell morphology of grains and the no remarkable increase in the amount of intergranular phase, the high performance with high energy product of 46.6 MGOe and high coercivity of 20.5 kOe could be obtained in the sintered (Nd,Dy)-Fe-B composite magnets.
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影响因子：
3.2
作者：
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通讯作者：
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影响因子：
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影响因子：
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