添加MgF_2对烧结NdFeB磁体的性能和微观组织的影响  

Effects of MgF_2 on Properties and Microstructure of Sintered NdFeB Magnets

作　　者：徐芳[1] 董显平[1] 张澜庭[1] 刘琼珍[1] 王静[1] 吴建生[1] 

机构地区：[1]上海交通大学材料科学与工程学院先进材料研究中心高温材料研究所,上海200240

出　　处：《中国稀土学报》2011年第5期523-527,共5页Journal of the Chinese Society of Rare Earths

基　　金：上海应用材料研究与发展基金(08520740200)资助

摘　　要：采用晶界添加MgF2制备烧结NdFeB磁体,通过扫描电镜、透射电镜和性能测试,研究了烧结NdFeB磁体的微观组织及其对磁性能、电阻率的提高和耐腐蚀性能的影响。结果表明:添加适量MgF2可实现在磁体剩磁、矫顽力和电阻率提高的基础上,同时提高材料的腐蚀电位,并且在极化曲线的阳极部分相同电位条件下,具有较小的极化电流密度,从而达到改善NdFeB磁体耐腐蚀性能的目的。磁体显微组织研究表明F元素进入晶界相,形成F含量约为30%(原子分数)、以面心立方为基的有序的NdOxFy相,其与磁性能、电阻率的提高和耐腐蚀性能改善有关。The sintered NdFeB magnets with MgF2 additives were prepared. It was found that remanence, coercivity and electrical resistivity increased with small amount of additives. Furthermore, the corrosion potential of magnets with MgF2 additives was more positive, and the magnets had lower polarization current density under the same applied potential in the anodic branch of the polarization curve than that of magnets without additives. It was indicated that the intergranular addition of MgF2 could improve corrosion resistance of NdFeB magnets. The microstructure of sintered NdFeB magnets was studied using SEM and TEM observation. It was indicated that a new neodymium oxyfluoride （ NdOxFy ） phase containing - 30% F （ atom fraction） with ordered fcc structure was formed in NdFeB magnet. The increase of magnetic properties, electrical resistivity and corrosion resistance could be related to the ordered grain boundary phase.

关 键 词：NDFEB磁体 磁性能 电阻率 抗腐蚀性能 NdOxFy相 稀土 

分 类 号：TG146.1[一般工业技术—材料科学与工程] TM273[金属学及工艺—金属材料]