晶粒细化对烧结钕铁硼晶界扩散过程及磁性能的影响

Effect of Grain Refinement on Grain Boundary Diffusion Process and Magnetic Properties of Sintered NdFeB Magnets

摘要:

制备了3种成分相同、晶粒尺寸不同的钕铁硼磁体，并在相同的技术参数下使用金属Tb进行了晶界扩散。使用X射线衍射、场发射扫描电子显微镜和电子探针显微分析仪评估扩散过程并对磁体扩散前后的磁性能进行了表征，研究了晶粒尺寸对烧结NdFeB磁体晶界扩散过程和性能的影响。结果表明，磁体的晶粒细化可以提高Tb扩散效率，并使磁体在不同温度下具有更高的矫顽力。这主要是由于在晶界扩散过程中磁体内部形成了更深、更完整的核壳结构，从而使Nd₂Fe₁₄B晶粒具有更好的磁隔离和各向异性。研究表明在低含量重稀土元素的情况下，细化晶粒可以提高磁体矫顽力。

Abstract:

Three types of NdFeB magnets with the same composition and different grain sizes were prepared, and then the grain boundary diffusion was conducted using metal Tb under the same technical parameters. The effect of grain size on the grain boundary diffusion process and properties of sintered NdFeB magnets was investigated. The diffusion process was assessed using X-ray diffractometer, field emission scanning electron microscope, and electron probe microanalyzer. The magnetic properties of the magnet before and after diffusion were investigated. The results show that the grain refinement of the magnet leads to higher Tb utilization efficiency and results in higher coercivity at different temperatures. It can be attributed to the formation of a deeper and more complete core-shell structure, resulting in better magnetic isolation and higher anisotropy of the Nd₂Fe₁₄B grains. This work may shed light on developing high coercivity with low heavy rare earth elements through grain refinement.