Effects of REFe2 on microstructure and magnetic properties of Nd-Ce-Fe-B sintered magnets
Effects of REFe2 on microstructure and magnetic properties of Nd-Ce-Fe-B sintered magnets
复制标题
REFe2对Nd-Ce-Fe-B烧结磁体组织和磁性能的影响
DOI：
10.1016/j.actamat.2017.02.002
复制
发表时间：
2017-04-15
期刊：
影响因子：
9.4
通讯作者：
Yan, Mi
中科院分区：
文献类型：
--
作者：
Zhang, Yujing;Ma, Tianyu;Yan, Mi
通过二元主相(BMP)方法，即烧结无Ce和含Ce的RE2Fe14B(RE，稀土)粉末的混合物，显著提高了NdFeB磁体中Ce的含量。在高Ce含量的NdCe-Fe-B磁体中形成的REFe2相由于其软磁性而被认为是对磁性能有害的。在本工作中，我们发现熔点低于2：14：1的REFe2相对优化NdCe-Fe-B BMP磁体的微结构和保磁性能具有积极的作用。在REFe2相熔点以上烧结可改善2：14：1相的润湿性，促进磁体致密化，形成连续光滑的晶界(GB)相。这有助于减弱相邻颗粒之间的短程交换耦合，从而确保BMP磁体的磁性能优于平均成分相同的单一主相磁体。结果表明，在BMP磁体中，当Ce含量为45wt%时，仍可获得B-r=12.4 kg，H-Cj=9.0 Koe，(BH)(Max)=36.7 MGOe的磁性能。(C)2017 Acta Materialia Inc.由Elsevier Ltd.出版。保留所有权利。
Ce substitution level in Nd-Fe-B magnets has been significantly increased via the binary main phase (BMP) approach, i.e. sintering the mixture of Ce-free and Ce-containing RE2Fe14B (RE, rare earth) powders. REFe2 phase that forms in the high Ce-containing Nd-Ce-Fe-B magnets has been considered to be harmful to magnetic performance due to its soft magnetism. In this work, we found that REFe2 phase with lower melting point than the 2:14:1 phase plays positive role on optimizing the microstructure and retaining magnetic performance of the Nd-Ce-Fe-B BMP magnets. The wettability of 2:14:1 phase can be improved by sintering above the melting point of REFe2 phase, which promotes densification of the magnet and the formation of continuous and smooth grain boundary (GB) phases. This contributes to the weakened short-range exchange coupling between adjacent grains, hence ensures superior magnetic performance of BMP magnets to the single main phase (SMP) ones with the same average composition. As a result, magnetic properties of B-r = 12.4 kG, H-cj = 9.0 kOe and (BH)(max) = 36.7 MGOe can be obtained even when 45 wt % Ce substitutes for Nd in the BMP magnets. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.