The grain boundary phase (GBP) has a significant influence on the magnetization behavior in nanocrystalline PrNd–Fe–B magnets. The current study demonstrates that reversible/irreversible magnetization behavior and the phenomenon of open recoil loops are related to both the nature of GBPs and the magnetization state by in situ observation. The optimization of GBPs nature (increase the volume fraction and improve the composition of GBPs) leads to the suppression of reversible magnetization behavior and the phenomenon of open recoil loops at low fields. Since the asymmetric magnetic domain structure appears only at low cycle fields, the openness phenomenon originates from the weak pinning grain boundaries (GBs). In addition, optimization of the GBPs also enhances pinning strength and uniformity, which contributes to the domain walls being pinned in the GBs at higher external fields. At this moment, the domain wall is dominated by irreversible magnetization behavior, and the openness phenomenon disappears. This proves that the coercivity mechanism is transformed from inhomogeneously weak pinning to homogeneously strong pinning with the optimization of GBPs. Consequently, the coercivity and squareness factor are significantly enhanced. This study sheds light on the understanding of the effects of GBP's nature on recoil loops and coercivity mechanism, and it also provides significant guidance for the development of advanced permanent magnets.

中文翻译：

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通过原位观察纳米晶 PrNd-Fe-B 磁体的磁化行为，分析晶界相对反冲环的影响


晶界相 （GBP） 对纳米晶 PrNd-Fe-B 磁体的磁化行为有重大影响。目前的研究表明，通过原位观察，可逆/不可逆磁化行为和开反冲环现象与 GBP 的性质和磁化状态有关。GBPs 性质的优化（增加体积分数并改善 GBPs 的组成）导致抑制可逆磁化行为和低场开反冲环现象。由于不对称磁畴结构仅出现在低周磁场中，因此开放性现象源于弱钉扎晶界 （GB）。此外，GBP 的优化还增强了固定强度和均匀性，这有助于在更高的外部场中将域壁固定在 GB 中。此时，畴壁以不可逆的磁化行为为主，开放现象消失。这证明了矫顽力机制随着 GBPs 的优化而从非均匀弱固定转变为均匀强固定。因此，矫顽力和垂直系数显着增强。本研究阐明了 GBP 的性质对反冲环和矫顽力机制的影响，也为先进永磁体的开发提供了重要的指导。