Abstract Multi-main-phase (MMP) Nd-Ce-Fe-B magnets prepared by sintering the mixture of Ce-free and Ce-containing RE 2 Fe 14 B (RE, rare earth) powders have been found to possess superior magnetic properties to the single-main-phase (SMP) ones. Purpose of this work is to further enhance the coercivity through restructuring the grain boundaries (GBs), which have strong influence on the short-range exchange coupling between adjacent grains. By incorporating 4 wt.% NdH x powders as the intergranular additive, coercivity of the (Pr, Nd) 22.3 Ce 8.24 Fe bal B 0.98 (wt.%) MMP magnet has been substantially increased from 8.2 kOe to 13.1 kOe. Magnetic domain characterizations and the recoil loop measurements showed that the exchange coupling between adjacent grains has been weakened significantly due to the formation of continuous and smooth RE-rich GBs by the extra Nd after NdH x dehydrogenation. Elemental distribution analysis revealed that thicker Nd-rich 2:14:1 shells with stronger magnetocrystalline anisotropy have been formed in the outer region of the Ce-rich main phase grains, which is beneficial to enhance their effective anisotropy. In addition, the Ce-rich 2:14:1 shells surrounding the Nd-rich 2:14:1 grain cores became thinner, which is beneficial to weaken the magnetic dilution effect of such grains. Micromagnetic simulation results also suggest that the coercivity can be further enhanced once the grain boundary is nonmagnetic. Technically, enriching RE elements or reducing Fe content can weaken the ferromagnetism of the grain boundary phase as well as the exchange coupling between adjacent grains. The above findings might shed new insights into enhancing the coercivity of low cost Nd-Ce-Fe-B magnets.

中文翻译：

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Nd氢化物多主相Nd-Ce-Fe-B烧结磁体的晶界重构

摘要 通过烧结不含 Ce 和含 Ce 的 RE 2 Fe 14 B（RE，稀土）粉末的混合物制备的多主相 (MMP) Nd-Ce-Fe-B 磁体具有优异的磁性能。到单主相 (SMP) 的。这项工作的目的是通过重组晶界（GBs）来进一步提高矫顽力，这对相邻晶粒之间的短程交换耦合有很大的影响。通过加入4wt.% NdH x 粉末作为晶间添加剂，(Pr, Nd) 22.3 Ce 8.24 Fe bal B 0.98 (wt.%) MMP磁体的矫顽力从8.2 kOe显着增加到13.1 kOe。磁畴表征和反冲环测量表明，由于 NdH x 脱氢后额外的 Nd 形成连续且光滑的富含 RE 的 GB，相邻晶粒之间的交换耦合已显着减弱。元素分布分析表明，在富Ce主相晶粒的外部区域形成了更厚的富Nd 2:14:1壳，具有更强的磁晶各向异性，这有利于增强它们的有效各向异性。此外，围绕富Nd 2:14:1晶粒核的富Ce 2:14:1壳变薄，有利于削弱此类晶粒的磁稀释作用。微磁模拟结果还表明，一旦晶界是非磁性的，矫顽力可以进一步增强。从技术上讲，富集RE元素或降低Fe含量会削弱晶界相的铁磁性以及相邻晶粒之间的交换耦合。上述发现可能为提高低成本 Nd-Ce-Fe-B 磁体的矫顽力提供新的见解。