Sn对Nd-Fe-B合金高温(423K)磁后效和畴壁钉扎的影响

MAGNETIC VISCOSITY AND DOMAIN WALL PINNING IN Nd-Fe-B MAGNET DOPED Sn AT 423 K

研究了Ｎｄ－Ｄｙ－Ｆｅ－Ｂ和Ｎｄ－Ｄｙ－Ｆｅ－Ｂ－Ｓｎ合金在４２３Ｋ的磁后效，发现两者的磁化强度都按时间对数衰减，Ｎｄ－Ｄｙ－ Ｆｅ－Ｂ－Ｓｎ合金的磁后效起伏场Ｈ_ｆ大于Ｎｄ－Ｄｙ－Ｆｅ－Ｂ合金．用Ｇａｕｎｔ的畴壁钉扎理论分析该温度下两者的钉扎机制后发现，对 于Ｎｄ－Ｄｙ－Ｆｅ－Ｂ－Ｓｎ合金，按畴壁强钉扎模型计算的钉扎密度与显微分析一致，因而，其反磁化过程在此温度下由畴壁强钉扎控制。 而Ｎｄ－Ｄｙ－Ｆｅ－Ｂ合金的实验结果，与强钉扎模型计算结果不相符，进一步分析表明，Ｎｄ－Ｄｙ－Ｆｅ－Ｂ合金的磁化反转过程由局域化弱钉扎控制。

Magnetic viscosities of Nd-Dy-Fe-B and Nd-Dy-Fe-B-Sn were investigated at 423 K. It is shown that the time dependence of the magnatization decay is logarithmic. The fluctuation field of Nd-Dy-Fe-B-Sn is larger than that of Nd-Dy-Fe-B. After analyzing with Gaunt's pinning theory, it is found that pin density calculated by the strong pinning model is in agreement with experiment for Nd- Dy-Fe-B-Sn. So the coercivity of Nd-Dy-Fe-B-Sn is controlled by strong pinning of domain wall, but Nd-Dy-Fe-B by localized weak pinning.