Abstract The high-coercivity Nd-Fe-B magnets with “core-shell” structure grains were prepared by doping TbCu powders and hot pressing after pre-sintering in the traditional powder metallurgy process. The coercivity for the hot-pressed pretreated Nd-Fe-B magnet is obviously enhanced to 28.6 kOe from 24.3 kOe by TbCu alloy doping. The Tb contents at the shell structure of grain in the hot-pressed pretreated magnet is 5.7 wt% while that in the dual-alloy magnet is 3.0 wt%. The enrichment of Tb elements in the shell layer further enhances the anisotropy of the grain surface and effectively improves the utilization efficiency of heavy rare earths. The existence of the hard (Tb, Nd)2Fe14B shell, which can effectively inhibit the reverse nucleation of magnetic domains, contribute to enhance the coercivity with few reduction of the remanence. Compared with the grain boundary diffusion process, this technology can be used to prepare large pieces of high performance Nd-Fe-B bulk magnets without diffusion depth limit.

中文翻译：

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TbCu掺杂Nd-Fe-B磁体通过预烧结和热压工艺改变晶界结构并提高矫顽力

摘要 采用传统粉末冶金工艺，通过掺杂TbCu粉体，经预烧结后热压制备具有“核-壳”结构晶粒的高矫顽力Nd-Fe-B磁体。通过 TbCu 合金掺杂，热压预处理 Nd-Fe-B 磁体的矫顽力从 24.3 kOe 明显提高到 28.6 kOe。热压预处理磁体中晶粒壳结构的Tb含量为5.7 wt%，而双合金磁体中的Tb含量为3.0 wt%。壳层中Tb元素的富集进一步增强了晶粒表面的各向异性，有效提高了重稀土的利用效率。硬(Tb, Nd)2Fe14B壳的存在可以有效地抑制磁畴的反向成核，有助于提高矫顽力，而剩磁几乎没有降低。