(中南工业大学 粉末冶金国家重点实验室，长沙 410083)
摘 要: 通过Kronmüller微磁学矫顽力模型拟合不同温度下测得的矫顽力，分析了Sn对三元NdFeB合金和NdDyFeB合金磁性能的影响及与显微组织的关系。发现掺杂Sn并未改变合金的矫顽力机制，在150 ℃以下，合金的反磁化过程由形核控制；在150 ℃ 以上，则由畴壁钉扎控制。然而，掺杂Sn却使两者的局部有效退磁因子Neff都减小，同时也增大了晶粒表面缺陷对矫顽力的影响。局部退磁因子减小，是NdDyFeBSn合金矫顽力提高的主要原因。而对于NdFeBSn合金，晶粒表面缺陷增大的影响超过了局部退磁因子减小的作用，故矫顽力反因Sn的存在而降低。在150℃以上，NdDyFeBSn合金中能形成更为有效的钉扎中心。
关键字: NdFeB磁体；掺杂；矫顽力机制；微磁学
（State Key Laboratory for Powder Metallurgy,
Central South University of Technology, Changsha 410083, P.R.China）
Abstract:The correlation of magnetic properties and microstructural improvement of NdFeB doped Sn was analyzed by fitting temperature dependence of coercivity with Kronmüller's model. Results showed that coercive mechanism is not changed by doping Sn. Beneath 150℃, nucleation controls demagnetization and pinning of domain wall determines it above 150℃. However, microstructural parameters, Neff and αK, are reduced because of doping Sn. The reduction of localized effective demagnetic field improves the coercivity of NdDyFeBSn. For NdFeBSn, decrement of coercivity by imperfections at the grain surface is larger than coercivity increment by reducing Neff. Above 150 ℃, more effective pin-site can be formed by doping Sn.
Key words: NdFeB magnet; doping; coercive mechanism; micromagnetism
