碳对钕铁硼磁性能及显微结构影响的微观机理研究

对不同碳含量的钕铁硼永磁体的磁性能，及显微结构进行了实验研究，磁性能测量结果表明，碳含量增加会导致Ｎｄ２Ｆｅ１４Ｂ四方相（主相）的衍射谱线的强度减弱，相应ａ－Ｆｅ相和富Ｎｄ相的衍射谱线强度增强。相应的金相组织观察结果表明，碳含量的增加，有利于富Ｎｄ相和富Ｂ相的增加，使钕铁硼合金中Ｎｄ２Ｆｅ１４Ｂ晶粒变小，晶界增大，晶粒外延层增厚，使Ｎｄ２Ｆｅ１４Ｂ晶粒的形核场减小，导致钕铁硼磁体的矫顽力减小，并且这种变化随碳含量的增加越显著。对钕铁硼磁体耐腐蚀性能观察结果表明，由于碳引起钕铁硼合金中富钕相的增加，并且由于富钕相对湿气极为敏感，致使钕铁硼磁体的耐腐蚀能力随碳含量的增加而降低。

MICRO-MECHANISM OF THE EFFECT OF CARBON ON MAGNETISM AND MICROSTRUCTURE OF Nd-Fe-B

An experimental study has been given to the magnetism and microstructure of Nd- Fe- Bwith different carbon content.The result indicates that the increase of carbon content will weaken the strength of diffracted rays of the tetragonal phase of Nd2Fe14B,while that of thea- Fe phase and rich Nd phase will be made stronger.The observation of the related metallur- gical structure shows that the increase of carbon content is advantageous to the increase ofboth rich Nd phase and rieh B phase,which leads to the shrinking of crystalized particles in Nd2Fe14B alloy,the thickening of outer edge layer and the extending of boundary Thus,theshaped nuclear field of Nd2Fe14B particlcs is reduced,and consequently,the magnetic retentiv- ity of Nd2Fe14B is lessened.This phenomenon gets more pronounced along with the increase of Carbon content.The corrosion- resisting performance of Nd- Fe-B has also been observed. The experiment shows that,with the increase of rich Nd phase caused by carbon ingredient,and owing to the high sensitivity of rich Nd phase to humidity, the corrosion resistingability of Nd2Fe14B magnet weakens as the carbon content increases.