Coercivity enhancement mechanism of Tb-diffusion Nd-Fe-B sintered magnets studied by magneto-optical Kerr optical microscope

作     者：Dan Wu Wei-Qiang Liu Ming Yue Qiong Wu Dong-Tao Zhang Qing-Mei Lu Xu-Liang Li Jing-Wu Chen Dan Wu;Wei-Qiang Liu;Ming Yue;Qiong Wu;Dong-Tao Zhang;Qing-Mei Lu;Xu-Liang Li;Jing-Wu Chen

作者机构：Key Laboratory of Advanced Functional MaterialsCollege of Materials Science and EngineeringBeijing University of TechnologyMinistry of Education of ChinaBeijing 100124China State Key Laboratory of Rare Earth Permanent Magnetic MaterialsHefei 231500China 

出 版 物：《Rare Metals》 (稀有金属（英文版）)

年 卷 期：2021年第40卷第3期

页      面：570-574页

核心收录：

学科分类：08[工学] 080502[工学-材料学] 0805[工学-材料科学与工程（可授工学、理学学位）] 

基　　金：financially supported by the National Key Research and Development Program of China(No.2018YFC1903405) Advanced Subject of Beijing China(No.PXM2019014204500031) the National Natural Science Foundation of China(Nos.51371002 51331003 and 51201037) the 2011 Cooperative Innovation Center of Beijing University of Technology the Importation and Development of High-Caliber Talents Project of Beijing Municipal Institutions 

主　　题：Coercivity enhancement mechanism Magnetic domain Grain boundary diffusion Nd-Fe-B sintered magnets 

摘      要：The coercivity,microstructure,and magnetic domain structure of Nd-Fe-B sintered magnets by grain boundary diffusion process(GBDP) with TbH3 nanoparticles were systematically *** to the original magnet,the coercivity(Hci) of the GBDP magnets improved from 1702 to 2374 kA·m^(-1) with few remanence reduced from 1.338 to 1.281 *** probe microanalysis(EPMA) analysis showed that Tb diffused along grain boundary,mainly concentrated in the boundary layer of the main phase,and formed a core-shell ***-optical Kerr optical microscope(MOKE) analysis showed that there were two types of magnetic domain reversal in one grain:gradual reversal(GR) and abrupt reversal(AR).When the applied field decreased from saturated magnetic field,the reversal magnetic domain nucleated and then spread over the whole grain gradually,which was called ***,some grains kept the single domain state until Hh which was a value of reverse direction applied field in second quadrant in hysteresis *** the applied field increased above Hh,reversed magnetic domain would suddenly appear and occupy most of the area of the grain,which was called *** is because AR grains have higher reversed magnetic domain nucleation field(HRN2) than GR grains(HRN1).After GBDP,the area of AR region increased obviously and GR region decreased accordingly,indicating that the core-shell structure could change GR grain into AR *** coreshell structure could suppress flipping of the magnetization of the grains due to the large magnetic anisotropy of Tbrich ***,large AR area led to high coercivity.