烧结Nd-Fe-B磁体非稀土Al的晶界扩散研究

Grain Boundary Diffusion of Non-Rare Earth Al for Sintered Nd-Fe-B

以Al粉作为扩散源,研究了不同晶界扩散工艺对Nd-Fe-B磁体微观结构和磁性能的影响。研究发现,570℃/1h扩散时,磁体的综合磁性能最佳,其矫顽力和磁能积分别为1131kA/m和249kJ/m^3,较原始磁体分别提升了16%和9.6%,且磁体的温度稳定性也得到改善。微结构和成分分析研究表明,晶界扩散后,Al主要分布于晶间富稀土相,且其形貌由大块状进展为薄层状,界面也变得更为平直光滑,增强了对反磁化畴形核的抑制,减小了退磁场。此外,晶间富稀土相中的Al有助于腐蚀电位的提升,而腐蚀电流密度的降低则归因于富稀土相分布的变化。

Using Al powder as diffusion source,the influence of grain boundary diffusion processes on the microstructure and magnetic properties of Nd-Fe-B magnets was investigated.It is found that the optimum magnetic properties including the coercivity of 1131 kA/m and the maximum energy product of 249 kJ/m3 can be achieved,which are increased by 16%and 9.6%,respectively compared with those of the as-prepared magnet.Meanwhile,the temperature stability is also improved.Microstructural investigation reveals that after grain boundary diffusion,Al is mainly distributed in the intergranular RE-rich phase,and the morphology of RE-rich phase changes from large block to thin layer.Smoother and straighter interface can be obtained,which can restrain the nucleation of anti-magnetization domain,reducing the demagnetization field.In addition,the Al in the intergranular phase is beneficial in elevating the corrosion potential,and the decreased corrosion current density should be attributed to the changes of RE-rich phase distribution.