HDDR法制备NdFeB永磁体的高矫顽力研究  

Study on the Mechanism of the High Coercivity of NdFeB Magnets Prepared by HDDR Method

作　　者：张朋越[1] 泮敏翔[1] 朱津津[1] 葛洪良[1] 孙浩[1] 金一彪 

机构地区：[1]中国计量学院浙江省磁学重点实验室,浙江杭州310018 [2]横店集团东磁股份有限公司,浙江东阳322100

出　　处：《稀有金属材料与工程》2011年第6期1097-1101,共5页Rare Metal Materials and Engineering

基　　金：浙江省科学计划项目(2006C14014;2009C21010);浙江省优秀青年教师资助项目

摘　　要：采用X射线衍射分析、扫描电镜和BH测试仪分别研究HDDR法制备的NdFeB永磁体微结构、晶粒表面形貌及其磁性能。结果表明,HDDR法制备的磁粉再经1080℃高温真空烧结所获得的NdFeB永磁体,主要由四方相Nd2Fe14B(P42/mnm)和少量的富稀土相构成,扫描电镜相片显示主相平均晶粒尺寸约为12.3μm;采用Horta法计算得到样品(006)晶面的极密度因子约为3.5,表明该样品具有较高的c轴取向;不同温度下退磁曲线研究表明,室温下合金有较好的磁性能:磁能积(BH)max=264kJ/m3,剩磁Br=1.17T,矫顽力达到Hcj=2038kA/m;随温度的升高,磁性能各参数都单调下降,特别是矫顽力降低最为显著,从295K升温到448K过程中其值下降了1496kA/m;Hc(T)/Ms(T)与HmNin(T)/Ms(T)(Kronmüller-Plot)关系曲线研究表明,该合金的矫顽力机制为畴成核反转机制,其中微磁参数αk和Neff分别为1.39和1.75,是决定该合金高矫顽力的关键因素。The microstructure,surface morphology,and magnetic properties of the sintered NdFeB permanent magnet prepared by the HDDR method were analyzed by X-ray diffraction,scanning electron microscopy and BH magnetic measurement.Microstructural studies show that NdFeB magnets which were firstly prepared by HDDR powder and then sintered at the high-temperature of 1080 oC consist of a large amount of the tetragonal phase Nd2Fe14B（P42/mnm） and trace amount of rare earth-rich phase.SEM images indicate that the average grain size of the Nd2Fe14B phase is about 12.3 μm.The density factor of（006） crystal face of Nd2Fe14B phase is estimated as about 3.5 using Horta formula,suggesting that the sample has a strong c-axis orientation.The demagnetic curves at different temperatures show that at room temperature this sample has well magnetic properties,i.e.（BH）max 264 kJ/m3,remanence Br about 1.17 T,and coercive Hcj 2038 kA/m.With the temperature increasing,magnetic properties of the samples are monotonicly reduced,especially for the coercivity which is reduced by 1496 kA/m from 295 to 448 K.The coercivity mechanism of the NdFeB magnets prepared by HDDR method was analyzed by studying the behavior of Hc（T）/Ms（T） versus（T）/Ms（T）（Kronmüller-plot）.The results of Kronmüller-plot show that nucleation is the dominating mechanism for the magnetization reversal in these samples.Micromagnetic parameters αk of 1.39 and Neff of 1.75 are responsible for the high coercivity of magnetic alloys.

关 键 词：稀土永磁体 矫顽力 磁性能 

分 类 号：TM273[一般工业技术—材料科学与工程]