Abstract To solve the challenging hurdle of low coercivity, Pr80Al20 and Pr40Dy40Al20 diffusion is applied to the Nd-La-Ce-Fe-B sintered magnets with high La-Ce substitution (La-Ce/TRE = 40 wt%, TRE: total rare earth). Coercivity approaching 15 kOe with approximately 200% increment level is acquired for PrAl diffusion. Anomalously, PrDyAl diffusion cannot further enhance the coercivity whilst lowers the remanence drastically from 12.60 to 12.16 kG. This anomaly is correlated with the critical role of surface microstructure that consumes large amounts of expensive Dy, i.e. thick Dy/Fe-rich top layer, and below that Dy/Al diffusion into the interior of 2:14:1 grain. Such predominant Dy agglomeration at the surface region can well interpret that the negative role of Dy in deteriorating remanence is exacerbated, while its positive role in strengthening the local shell of 2:14:1 phase and enhancing the coercivity is weakened. Comparably, PrAl diffusion generates the Pr-rich magnetically hardening shell along the continuous grain boundary layer, paving it a versatile route for significant coercivity enhancement of Nd-La-Ce-Fe-B without sacrificing remanence.

中文翻译：

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PrAl 和 PrDyAl 扩散到 Nd-La-Ce-Fe-B 烧结磁体中：表面微结构在磁性能中的关键作用

摘要 为了解决低矫顽力的难题，Pr80Al20 和 Pr40Dy40Al20 扩散应用于具有高 La-Ce 取代（La-Ce/TRE = 40 wt%，TRE：总稀有）的 Nd-La-Ce-Fe-B 烧结磁体。地球）。PrAl 扩散获得了接近 15 kOe 的矫顽力，增量约为 200%。异常的是，PrDyAl 扩散不能进一步提高矫顽力，同时将剩磁从 12.60 急剧降低到 12.16 kG。这种异常与消耗大量昂贵 Dy 的表面微结构的关键作用有关，即厚 Dy/Fe 的顶层，以及在该层之下 Dy/Al 扩散到 2:14:1 晶粒内部。这种在表面区域占主导地位的 Dy 团聚可以很好地解释 Dy 在恶化剩磁中的负面作用加剧，而其增强2:14:1相局部壳层和增强矫顽力的积极作用减弱。相比之下，PrAl 扩散沿连续晶界层产生富含 Pr 的磁性硬化壳，为 Nd-La-Ce-Fe-B 显着增强矫顽力而不牺牲剩磁铺平了通用途径。