采用添加Nd₉₀Al₁₀低熔点合金调控制备了扩散用烧结Nd₂Fe₁₄B磁体，并采用Tb晶界扩散制备了相应的扩散磁体，分析了扩散磁体的晶界结构和成分对磁体矫顽力的影响。结果表明，添加质量分数为0.5%的Nd₉₀Al₁₀合金调控后，晶界扩散(GBD)后磁体的矫顽力提高到1439 kA/m，相对于未晶界调控的扩散磁体增加了530 kA/m。添加Nd₉₀Al₁₀低熔点合金不会影响GBD前磁体的Curie温度，但降低了磁体的低温相变温度。GBD后磁体Tb取代晶格中的Nd引起Nd₂Fe₁₄B相的晶格常数减小，从而使XRD谱中衍射峰位右移。经Nd₉₀Al₁₀调控后的扩散磁体表面处的主相晶粒的富Tb壳清晰可见。从距离磁体表面20 μm增加到100 μm时，富Tb壳层仍清晰可见。当深度继续增加到500 μm时，经Nd₉₀Al₁₀调控后的扩散磁体晶粒周围都有连续晶界相。经晶界调控的扩散磁体可见衬度明显的富Tb壳层，形成了非晶的富Nd相，增强了两两主相晶粒间的去磁耦合能力。Nd在富Nd相中心区域出现峰值，更多的富Nd相在晶界扩散过程中作为Tb向磁体内扩散的通道，Tb原子在富Nd相的浓度高达约35%，其扩散深度和使用效率明显提升。

The grain boundary diffusion (GBD) process is a remarkable achievement in sintered Nd-Fe-B permanent magnet manufacturing. Furthermore, the coercivity can be considerably improved by diffusing heavy rare earth (HRE) elements into the magnet along the grain boundary, and the reduced HRE consumption can also be realized. However, compared with parameters of GBD, previous research has focused less on improving the magnet. In this study, the magnet was prepared using low melting point alloy Nd₉₀Al₁₀ before GBD modification, after which the corresponding Tb-GBD was completed. The magnetic property results indicated that the coercivity increased to 1439 kA/m, which was 530 kA/m higher than the unmodified magnet. Thus, the effects of the grain boundary structure and composition on the coercivity were analyzed. The addition of Nd₉₀Al₁₀ did not affect the Curie temperature of the magnet, but it reduced the low-temperature phase transition temperature. The Tb replaced Nd at the margin of main phase, which moved the diffraction peak to the right in the XRD spectrum. Moreover, a clear Tb-rich shell surrounding the main phase formed in the diffused magnet modified by Nd₉₀Al₁₀ at the depth of 20 μm, and the shell could still be clearly observed at 100 μm. However, the main phase was surrounded by the continuous grain boundary when the depth increased to 500 μm in Nd₉₀Al₁₀ modified magnet by GBD. The Tb-rich shell was observed by TEM and a noncrystalline Nd-rich phase was observed. The content peak of the Nd element appeared in the central region of the Nd-rich phase. This, the diffused depth and usage efficiency remarkably improved, because the Nd-rich phase acted as a channel for Tb diffusion, with the concentration of Tb being as high as 35%.