镝扩渗对烧结钕铁硼磁体组织结构与磁性能的影响

对比研究了38UH、42SH和N50薄片状钕铁硼磁体晶界镝扩渗前后的组织结构与磁性能，发现经过镝扩渗处理后磁体的矫顽力提高了400 kA·m-1以上，而剩磁几乎不变，最大磁能积因为矫顽力和方形度的提高而提高。经组织结构分析认为，钕铁硼磁体晶界镝扩渗提高矫顽力主要是通过提高Nd₂Fe₁₄B晶粒外延层的各向异性和形核场实现的。根据Fick第一扩散定律，对磁体晶界镝扩渗进行了模拟计算，可近似得到定温热处理不同时间后渗镝深度及对应的镝的质量浓度及质量分数。 

Microstructure and magnetic properties of sintered Nd-Fe-B magnets by Dy diffusion treatment

The microstructure and magnetic properties of 38UH, 42SH and N50 magnets with and without Dy diffusion treatment were contrastively investigated. The intrinsic coercivity of the magnets by Dy diffusion increases over 400 kA·m-1 correspondingly but the remanence shows little decrease. The maximum energy product enhances with the increases in intrinsic coercivity and square degree. The evident enhancement of the intrinsic coercivity of the magnets results from the increases in magnetic anisotropy and nucleation field of the extensive layer of Nd₂Fe₁₄B grains. Based on the Fick's first law, the depth, mass concentration and mass fraction of Dy element with process time at a certain temperature can be approximately calculated.