Abstract Post-sinter annealing (PSA) plays an essential role on enhancing coercivity of the single-main-phase (SMP) Nd 2 Fe 14 B-based magnets due to the formation of continuous Nd-rich grain boundary (GB) layers to decouple the adjacent grains. Here we investigated the PSA effects on coercivity of the multi-main-phase (MMP) [(Nd,Pr) 0.55 Ce 0.45 ] 30.5 Fe bal M 1.0 B 1.0 (wt.%) magnet prepared by sintering the mixture of Ce-free and Ce-containing 2:14:1 powders, which has shown superior magnetic properties to the SMP one at the same average composition. The annealing temperature dependent investigation showed that the coercivity can be enhanced when annealing at low temperatures, but becomes even lower than that of the as-sintered state when annealing at higher temperatures, despite that continuous RE-rich GB layers are formed after annealing. When raising the annealing temperature, the RE gradients within the 2:14:1 phase grains are reduced to reach the ‘‘close to equilibrium (or SMP)’’ state due to the further elemental inter-diffusions among the Ce-lean and Ce-rich 2:14:1 grains, which weakens the magnetic impedance effect among them. These findings suggest a unique clue to enhance coercivity of the MMP RE-Fe-B magnets by PSA, i.e. the competitive contributions between the formation of continuous GB layers and the gradual chemical homogenization should be balanced.

中文翻译：

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烧结后退火对多主相Nd-Ce-Fe-B磁体矫顽力的影响

摘要 烧结后退火 (PSA) 在提高单主相 (SMP) Nd 2 Fe 14 B 基磁体的矫顽力方面起着至关重要的作用，因为形成了连续的富 Nd 晶界 (GB) 层以解耦。相邻的谷物。在这里，我们研究了 PSA 对多主相 (MMP) [(Nd,Pr) 0.55 Ce 0.45 ] 30.5 Fe bal M 1.0 B 1.0 (wt.%) 磁体矫顽力的影响，该磁体是通过烧结不含 Ce 的混合物制备的含铈的 2:14:1 粉末，在相同的平均组成下，它显示出优于 SMP 粉末的磁性能。退火温度相关的研究表明，在低温退火时矫顽力可以提高，但在高温退火时甚至低于烧结态，尽管退火后形成了连续的富含稀土的 GB 层。当提高退火温度时，2:14:1 相晶粒内的稀土梯度降低，达到“接近平衡（或 SMP）”状态，这是由于贫铈和铈之间进一步的元素相互扩散-丰富的2:14:1晶粒，削弱了它们之间的磁阻效应。这些发现表明了通过 PSA 增强 MMP RE-Fe-B 磁体矫顽力的独特线索，即连续 GB 层的形成与逐渐化学均质化之间的竞争贡献应该得到平衡。