择优取向对热压／热变形纳米NdFeB磁体腐蚀行为的影响

Effect of Preferred Orientation on Corrosion Behavior of Hot-pressed and Hot-deformed Nanocrystalline NdFeB Magnet

利用电化学测试技术和材料分析方法研究了择优取向对热压/热变形纳米NdFeB磁体腐蚀行为的影响。结果表明:不同取向的热压/热变形纳米NdFeB磁体的腐蚀行为相似,但与取向轴平行截面相比,与取向轴垂直截面具有更大的局部腐蚀倾向性以及更快的溶解速率;不同取向的热压/热变形纳米NdFeB磁体均发生Nd的优先腐蚀,且与取向轴垂直截面腐蚀产物膜中O的原子分数略大;富Nd相面积分数以及晶界数的差异是导致不同取向的热压/热变形纳米NdFeB磁体腐蚀行为差异的主要原因。

The effect of preferred orientation on the corrosion behavior of hot-pressed and hot-de- formed nanocrystalline NdFeB magnet was investigated by electrochemical measurements and ma- terials analysis methods. The results indicated that the preferred orientation had little effect on the corrosion behavior of hot-pressed and hot-deformed nanocrystalline NdFeB magnet. Polarization and electrochemical impedance spectroscopy （EIS） measurements showed that the cross section vertical to the preferred orientation exhibited a higher dissolution rate and susceptibility to local- ized corrosion in 3.5%NaC1 solution rather than that parallel to the preferred orientation. X-ray pho- toelectron spectroscopy （XPS） revealed that after immersion in 3.5% NaCl solution for 30 rain, both of the surfaces of the two sections showed selective corrosion of Nd. The slight differences in the corrosion behavior of the two eross sectinns were nrnhahly ascrihad tn their d]ffargrlea in thNd-rich phase proportions and the guantities of grain boundaries.