Abstract The ordering transformation of solid solution and the insufficient 1:5H boundary phase in the final magnets challenge the realization of high performance in Sm2Co17 magnets with high iron content. The investigation correlates the ordering degree of solid solutions to the cellular structure of the final magnets with the composition of Sm(CobalFexCu0.06Zr0.02)7.8 in which x ranges from 0.30 to 0.36. The ordering tendency of solid solution increases with increasing iron content. Rietveld structure refinement demonstrates that increasing iron content reduces the occupancy of Sm at Co-Co dumbbell sites in 2:17R, as well as Zr solubility on Sm 6c sites, leading to higher ordering degree and less Z planar phase formation separately. Antiphase boundaries (APBs) arising from the different 2:17R variants with the same or different directions were frequently observed in solid solutions, which facilitate the nucleation and formation of 1:5H phase during aging treatment. With increasing Fe content, the width of nanotwins increases and thus the APB density decreases in the solid solution. Furthermore, overlapping zones appear in solid solutions with higher Fe content, which will retain and enlarge as the twins grow during aging treatment, inhibiting the formation of 1:5H boundary phase. In addition, the density of Z phase declines and more defective platelet phases occur in x = 0.36 magnets, which depress the element diffusion and re-distribution during slow cooling. The above correlation between solid solution and cellular structure well explain the structure origin for the deterioration of magnetic performance with higher Fe content, which may provide guidance for further performance improvement in Sm2Co17 type magnets with higher iron content.

中文翻译：

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高铁含量Sm2Co17型磁体有序固溶体与蜂窝结构的相关性

摘要 最终磁体中固溶体的有序转变和 1:5H 边界相不足对实现高铁含量 Sm2Co17 磁体的高性能提出了挑战。该研究将固溶体的有序度与最终磁体的蜂窝结构与 Sm(CobalFexCu0.06Zr0.02)7.8 的成分相关联，其中 x 的范围为 0.30 至 0.36。固溶体的有序趋势随着铁含量的增加而增加。Rietveld 结构精修表明，增加铁含量会降低 Sm 在 2:17R 中 Co-Co 哑铃位点的占有率，以及 Zr 在 Sm 6c 位点的溶解度，导致更高的有序度和更少的 Z 平面相形成。由不同的 2 产生的反相边界 (APB)：在固溶体中经常观察到具有相同或不同方向的 17R 变体，这有利于时效处理过程中成核和 1:5H 相的形成。随着Fe含量的增加，纳米孪晶的宽度增加，因此固溶体中的APB密度降低。此外，铁含量较高的固溶体中会出现重叠区域，随着时效处理过程中孪晶的生长，重叠区域会保留和扩大，从而抑制了 1:5H 边界相的形成。此外，在 x = 0.36 的磁体中，Z 相的密度下降，有缺陷的片晶相出现更多，这抑制了缓慢冷却过程中元素的扩散和重新分布。上述固溶体与胞状结构的相关性很好地解释了铁含量较高时磁性能劣化的结构起源，