Effect of surface Nd-rich phase and oxygen content of melt-spun flakes on formation of coarse grains in hot-pressed Nd-Fe-B magnet  

作　　者：Yeyuan Du Wenzong Yin Renjie Chen Xu Tang Jinyun Ju Bin Chen Longquan Hou Aru Yan Jianhui Yuan 

机构地区：[1]School of Materials Engineering,Shanghai Collaborative Innovation Center of Laser Advanced Manufacturing Technology,Shanghai University of Engineering Science,Shanghai 201620,China [2]Key Laboratory of Magnetic Materials and Devices.Ningbo Institute of Materials Technology and Engineering,Chinese Academy of Sciences,Ningbo 315201,China [3]University of Chinese Academy of Sciences,Beijing 100049,China

出　　处：《Journal of Rare Earths》2021年第11期1389-1395,I0003,共8页稀土学报（英文版）

基　　金：Project supported by the Ningbo Science and Technology Major (2017B10002,2019B10093);the National Natural Science Foundation of China (51671207,51301192);Zhejiang Province Technology Application Research (LGG19E010001)。

摘　　要：Nd-Fe-B hot-pressed(HP) magnet prepared from melt-spun MQU-F flakes features coarse grains(CG)with the average size of both 200 nm(CGS) and 700 nm(CGL) at flake boundary.The grain growth at the flake boundary of Nd2 Fe14B/α-Fe composite HP magnet before and after diffusion of low-melting-point Pr82Cu18 phase was investigated,revealing the indispensable role of surface RE-rich phase of meltspun flakes in the formation of CG in HP magnet.The dominant role of surface oxygen content of melt-spun flakes in the formation of CGL has been clarified with etching method.The HP magnet prepared from the etched flakes with dramatically decreased oxygen content exhibits the CG regions merely with homoge neous equiaxed CGS at flake boundary.Consequently,the coercivity(μ0 Hc) shows significant increase while remanent magnetization(μ0 Mr) inappreciable change.Further investigation with sieving method reveals the elimination of CGL via removal of the fine Nd-Fe-B flakes smaller than 54 μm due to their much higher oxygen content,confirming the dominant role of oxygen content in the formation of CGL.The quantitative analysis on the magnetic properties of the above HP magnets reveals the monotonic increase of coercivity(μ0 Hc) and negligible change of remanent magnetization(μ0 Mr) with decreased oxygen contents of Nd-Fe-B flakes.The maximum value of coercivity(μ0 Hc) increases from2.26 to 2.47 T as the oxygen content decreases from 0.1692 wt% to 0.079 wt%.

关 键 词：Coarse grain Hot pressing ND-FE-B Oxygen content Nd-rich phase Rare earths 

分 类 号：TM273[一般工业技术—材料科学与工程]