基于快淬NdFeB粉末的放电等离子烧结永磁的组织和性能

Microstructure and Properties of NdFeB Magnets Prepared by Spark Plasma Sintering Using Melt Spun Powder

利用纳米晶快淬NdFeB粉末为原材料,采用放电等离子烧结(SPS)技术制备了高密度各向同性块体永磁。研究了放电等离子火花烧结磁体不同部位的磁性能和显微组织形貌,比较了烧结压力对磁体的组织和性能的影响。结果表明,由于组织的差异,烧结磁体不同部位磁性能略有不同,内部的剩磁较高,磁体边缘的矫顽力较高,而半径中点处的综合磁性能最好。烧结压力对烧结磁体的密度、显微组织,晶粒大小和形状以及磁性能都有重要影响。高的烧结压力有利于提高磁体密度、减小粗晶区体积、改善磁性能。SPS磁体中存在明显的晶间交换耦合作用。

Isotropic NdFeB magnets with high density were prepared by spark plasma sintering （SPS） technique taking melt spun nano-crystalline powder as raw materials. The magnetic properties and microstructure morphologies were studied. The effects of sintering pressure on the microstructure and properties of the magnet were compared. The results show that the microstructure and magnetic properties are slightly varied in the magnet from the center to the edge. The samples taking from the center of the magnet have high remanence, whereas that from the edge have high coercivity. The SPS pressure has important effects on the density, microstructure, grain size and shape, as well as magnetic properties. The magnets with high density, reduced coarse grain zone and improved properties can be produced under high SPS pressure. In addition, the intergranular exchange coupling is also found in the SPS magnet.