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Numerical simulation of single roller melt spinning for NdFeB alloy based on finite element method

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Rare Metals 2020年第10期39卷 1145-1150页

作者： Xu-Chao Wang ming Yue Dong-Tao Zhang Wei-Qiang Liu ming-gang zhu College of Materials Science and Engineering Beijing University of TechnologyBeijing 100124.China Central Iron and Steel Research Institute Beijing 100081China

The numerical simulation model of single roller melt spinning for rapid quenching process of NdFeB alloy was built,and the vacuum chamber,cooling roller and sample were taken into account as a *** existing mature technology was in order to verify the correctness of *** rapid quenching ribbons with different roll speeds were used as the simulation *** results of the numerical simulation and experiments show that the validity of the model has been testified and the reasons of the formation of complete quenching ribbons and by-product have been *** experimental thickness of the ribbons is proportional to the theoretical *** the same spray condition,with the roll speed increasing,the thickness decreases *** the speed range of25-30 m·s^(-1),the simulated calculation date is close to the experimental date,which can be considered as an ideal technological parameter.

关键词： NdFeB Melt spinning Finite element method Numerical simulation

Corrosion behavior of dual-main-phased(Nd_(0.8)Ce_(0.2))2Fe_(14)B magnets with and without annealing process

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Rare Metals 2023年第2期42卷 585-590页

作者： Xiao-Ning Shi ming-gang zhu Rui Han Li-Wei Song Wei Li Division of Functional Material Central Iron&Steel Research InstituteBeijing100081China

In this work,the corrosion behavior of the sintered Nd_(2)Fe_(14)B in which Nd was substituted by Ce to form dual-main-phased magnet with/without annealing process was *** mass loss of as-sintered magnets(SM)is larger than that of as-annealed magnets(AM)in the accelerated corrosion *** particular,the mass loss of SM increases sharply when the corrosion time increases to48 *** free corrosion current of the SM samples is larger than that of AM in 0.1 mo1·L^(-1)HCl;this is due to that the content of RE-rich phase at the intergranular triple junctions(TJs)of the SM samples is larger than that of AM samples and the corrosion rate of the RE-rich phase at the TJs is higher than that at grain *** the free corrosion current of the SM samples is smaller than that of AM samples in 3.5 wt%NaCl as the electron transfer resistance(R_(ct))of SM is larger than that of *** loop in the Nyquist diagrams at low frequency of SM is observed,which originated from the *** shows that pitting of SM occurs more easily than that of *** morphology of samples indicates that the corrosion area of SM is bigger and deeper than that of AM after accelerated corrosion for 60 *** the annealing process,the distribution of rare-earth-rich phase becomes more uniform,which changes the free corrosion current and effectively suppresses the occurrence and propagation of pitting.

关键词： NdFeB magnet Annealing process Intergranular corrosion Pitting corrosion

Microstructures and magnetic properties of Sm(Co_(bal)Fe_(0.245)Cu_(0.07)Zr_(0.02))_(7.8)sintered magnet solution-treated at high temperature

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Rare Metals 2022年第12期41卷 4230-4234页

作者： Wei Sun ming-gang zhu Yi-Kun Fang Zhao-Hui Guo Wei Li Functional Materials Research Institute Central Iron and Steel Research InstituteBejing 100081China Beijing Engineering Laboratory of Advanced Metallic Magnetic Materials and Preparation Techniques Beijing 100081China

Sm(CoFeCuZr)zsintered permanent magnet has been attracting a great deal of attention by virtue of its high-temperature magnetic properties,low temperature coefficient and good corrosion and oxidation *** microstructures and magnetic properties of Sm(Co_(ba1)Fe_(0.245)Cu_(0.07)Zr_(0.02))_(7.8)sintered permanent magnet prepared by a traditional powder metallurgy method were *** magnetic properties,especially the maximum magnetic energy product,(BH)max,were obtained through adjusting solution-treated *** solution-treated temperature increasing from 1155 to 1195℃,remanence(Br)almost keeps constant and knee point coercivity(Hk),magnetic induction coercivity(H_(cb))and(B_(H))maxfirst increase and then *** intrinsic coercivity(H_(cj))of magnet solution-treated at 1195℃is 738 kA·m^(-1),which is less than 2/5 that of magnet solution-treated at 1183℃(>1927 kA·m^(-1)).The reason that magnet solution-treated at 1195℃shows lower Hcjthan magnet solution-treated at 1183℃is considered to be mainly related to the fact that there are a lot of cells with abnormally small *** addition,the lattice constant of Sm(Co_(bal)Fe_(0.245)Cu_(0.07)Zr_(0.02))_(7.8)sintered permanent magnet solution-treated at 1195℃,given by indexing highresolution transition electron microscope(HRTEM)results,is considered to be related to the formation of cells with abnormally small size which decreases H_(cj).

关键词： Microstructures Magnetic properties Sm(CoFeCuZr)_(z)sintered magnet High solution-treated temperature

Magnetic properties and structures of Y-substituted Nd-Y-Fe-B melt-spun ribbons

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Rare Metals 2023年第5期42卷 1712-1717页

作者： Meng Zheng Yi-Kun Fang Li-Wei Song Rui Han ming-gang zhu Wei Li Division of Functional Materials Central Iron and Steel Research InstituteBeijing100081China

The nanocrystalline magnetic ribbons of(Nd_(1-x)Y_(x))_(14.5)Fe_(ba1)B(6)Co_(0.2)Al_(1)Cu_(0.15)(x=0,0.1,0.2,0.3,0.4) were prepared by melt-spinning *** magnetic properties and microstructures were systematically investigated for the *** is found that Y substituting Nd in the R_(2)Fe_(14)B main phase grains gives rise to the decrease in the crystal lattice *** Y content increases from x=0 to x=0.4,the remanence and intrinsic coercivity(H_(cj)) decrease from 0.80 to 0.71 T and1400 to 809 kA·m^(-)1,respectively,with the corresponding descent rate of 11.5% and 42.5%.It is impressed that the average grain size increases with Y content *** the strong intergrain exchange coupling interactions exist in all the ribbons and could be enhanced with an appropriate Y substitution,such as x=***,magnetization reversal mechanism is confirmed to be pinning type for the *** results provide valuable reference to the fabrication of Y-substituted Nd-Y-Fe-B sintered magnets.

关键词： Melt-spun ribbons Y substitution Intergrain exchange coupling Microstructure

Microstructure and magnetic properties of anisotropic hot-deformed magnet of different magnetic particle sizes

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Rare Metals 2015年第4期34卷 255-258页

作者： Xu-Chao Wang ming-gang zhu Wei Li Yan-Feng Li Bin Lai An Du Division of Functional Materials Research Central Iron & Steel Research Institute College of Sciences Northeastern University

In this paper, the magnetic Nd-Fe-B particles of different sizes were conducted under vacuum by the hot pressing, then cooled quickly to room temperature. Finally hot deformation was performed to get the anisotropy Nd-Fe- B magnet at a deformation rate of 70 % in the protection of argon atmosphere. NIM-2000 was used for the measurement of hysteresis loop of the samples. Meanwhile, scanning electron microscopy （SEM） was used to observe the surface morphology of the magnetic particles with different sizes and hot-deformed magnets, energy spectrum analyzer to analyze the composition of magnetic particles. The effect of magnetic particle sizes on the microstructure and magnetic properties of the hot-deformed anisotropic magnet was investigated. Anisotropic hot-deformed magnets produced from the maximum particle size of 200-350 μm have the highest magnetic properties of Br = 1.465 T, Hcj = 1,157 kA.m-1, （Bn）max = 425 kJ.m-3.

关键词： Magnetic property Hot-deformed magnet Magnetic particle Size

Development of Ce-based sintered magnets: review and prospect

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Journal of Iron and Steel Research International 2020年第1期27卷 1-11页

作者： An-hua Li Long-long Xi Hai-bo Feng Ning Zou Min Tan ming-gang zhu Wei Li Division of Functional Material Central Iron&Steel Research InstituteBeijing 100081China Ningbo Funeng New Material Company Ningbo 315336ZhejiangChina

Ce-based magnets have attracted extensive attention in both academia and industry due to their excellent property-price ratio and distinctive phase ***,Ce-based sintered magnets have widely tunable magnetic properties with changing Ce ***,they can be used to meet many different application requirements from packaging market to driving motors,*** intrinsic magnetic properties,phase composition,and microstructures of the Ce-based sintered magnets with different Ce contents have been *** service performances such as temperature stability,corrosion resistance,mechanical properties and thermal expansion of commercial Ce-based sintered magnets are *** research and development trends of the Ce-based magnets in the future are pointed out.

关键词： Ce-based sintered magnet Ce content Phase structure Magnetic property Service performance

Identification of optimal solid solution temperature for Sm_(2)Co_(17)-type permanent magnets with different Fe contents

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Rare Metals 2021年第12期40卷 3567-3574页

作者： Shuai Wang Hong-Sheng Chen Yi-Kun Fang Chao Wang Lei Wang ming-gang zhu Wei Li Division of Functional Materials Research Central Iron and Steel Research InstituteBeijing 100081China

It is confirmed that the solid solution temperature range to obtain optimal magnetic properties is different for the magnets with different Fe contents,and the correlation between magnetic properties and microstructures influenced by solid solution temperature(Ts)has been systematically *** optimal solid solution temperature range is 1413-1463 K for the Sm(Co_(bal)Fe_(0.213)Cu_(0.073)Zr_(0.024))_(7.6)magnet,which is higher than that of the Sm(Co_(bal)Fe_(0.262)Cu_(0.073)Zr_(0.024))_(7.6)magnet(1403-1453 K),and the optimal T_s range is about 50 K for both of the *** solid solution temperature range shifting toward relatively high temperature is due to the increase in a phase transition *** magnet solution-treated at proper temperature exhibits 1:7 H single phase,and intact cell structure and high Cu concentration(23.12 at%)in the cell boundary are found after aging process,which makes the magnet shows high intrinsic coercivity(H_(cj))and magnetic field at knee-point(H_(knee)).At a lower solid solution temperature,the 2:17 H,1:5 H and Zr-rich precipitation phases appear,which affects the cell structure,density of lamellar phase and Cu concentration in the cell boundary,leading to the reduced magnetic ***,at a higher solid solution temperature,there exist obviously light gray and dark regions with different Sm,Cu and Fe contents in scanning electron microscopy observation,and the magnet shows low pinning field in the two regions and incomplete cell structure,resulting in an inferior H_(cj)and H_(knee).

关键词： Sm_(2)co_(17)-type magnets Magnetic properties Solid solution treatment Iron content Microstructures

Coercivity enhancement of hot-deformed Nd-Fe-B magnets with Pr-Cu alloy addition

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Rare Metals 2023年第4期42卷 1403-1407页

作者： Jun-ming Wang Zhao-Hui Guo Zheng Jing Xiao Du Neng-Jun Yu Meng-Yu Li ming-gang zhu Wei Li Division of Functional Materials Central Iron&Steel Research InstituteBeijing100081China

Effects of low-melting Pr-Cu alloy addition on the microstructure and magnetic properties of the hot-deformation Nd-Fe-B magnets were investigated.A small amount of Pr-Cu addition enhances the coercivity of the hot-deformation Nd-Fe-B magnets *** coercivity of the hotdeformation Nd-Fe-B magnets with 4.0 wt%Pr_(85)Cu_(15)addition increases to 1271 kA·m^(-1),75.69%higher than that of Pr-Cu-free magnet(723 kA·m^(-1)),and then decreases with5 wt%Pr_(85)Cu_(15)*** is observed that there a uniform RE-rich phase is formed wrapping the Nd2Fe14B main phase in the sample with 4.0%Pr_(85)Cu_(15)addition by scanning electron microscopy(SEM),which promotes the *** angular dependence of coercivity for the hot-deformation Nd-Fe-B magnets indicates that the coercivity mechanism is nucleation combined with domain wall *** domain wall pinning is weakened,while the nucleation is enhanced after Pr-Cu ***,intrinsic coercivity,and maximum magnetic energy product of the original Nd-Fe-B magnet are 1.45 T,723 kA·m^(-1),and 419.8 kJ·m^(-3),respectively,and those of the sample with 4.0%Pr_(85)Cu_(15)alloy addition are 1.30 T,1271 kA·m^(-1),and 330.0 kJ·m^(-3),respectively.

关键词： Nd-Fe-B Low-melting alloy Hot-deformation Microstructure Coercivity mechanism

Microstructure and magnetic properties of sintered CeCo_(4.3252-x)Cu_(0.675)Fe_x magnets

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Rare Metals 2015年第3期34卷 164-167页

作者： Wei Sun ming-gang zhu Yi-Kun Fang Wei Pan Man-Long Xia Wei Li Division of Functional Materials Central Iron and Steel Research Institute Group

Anisotropic CeCo4.325_xCuo.675Fex （x ： 0.475- 0.875） sintered magnets were prepared by traditional powder metallurgical method. Influence of ball-nfilling time and iron content on microstructure and magnetic properties of the CeCo4,325-xCuo.675Fex sintered magnets were investigated. It is shown that the properties of the magnet produced by mag- netic powders ball-milled for 40 min are better than that for 30 rain. With iron content increasing, remanence Br and maxi- mum energy product （BH）m increase first and then decrease. The optimal magnetic properties are obtained for the CeCo3.65Cuo.675Feo.675 sintered magnet： Br=0.685 T, the intrinsic coercivity Hci = 350 kA.m-1, and （BH）m ： 85.6 kJ.m-3. The increase of Br is mainly influenced by iron content of 1：5 matrix which can properly increase the saturation induction Bs; the rapid increase of the amount of Ce-rich phase and 5：19 phase gives rise to the deterioration of the magnets when x ≥ 0.775.

关键词： Ce-Co-based permanent magnet Remanence Microstructure