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Magnetic properties and microstructures of terbium coated and grain boundary diffusion treated sintered Nd-Fe-B magnets by magnetron sputtering

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Journal of Rare Earths 2021年第2期39卷 167-173页

作者： Wei Zhu Yang Luo Zilong Wang Xinyuan Bai Haijun Peng dunbo yu National Engineering Research Center for Rare Earth Materials GRINM Group Co.Ltd.Beijing 100088China GRIREM Advanced Materials Co. Ltd.Beijing 100088China General Research Institute for Nonferrous Metals Beijing 100088China

Tb coating on the surface of commercial sintered Nd-Fe-B magnet was prepared by DC magnetron *** secondary heat treatment was used to regulate the microstructure for the enhancement of coercivity,namely diffusion treatment and annealing *** coercivity increases significantly from 18.3 to 28.0 kOe,the remanence decreases slightly from 14.1 to 14.0 kGs,and the comprehensive magnetic properties are higher than 75(Hcj+(BH)_(max)=76.7).SEM results indicate that,on the one hand,950℃is the optimal diffusion *** diffusion temperature results in insufficient diffusion of Tb *** diffusion temperature can lead to the main phase grain growth,the decrease of Nd-rich phase,and forming holes in the *** the other hand,500℃is the optimal annealing *** annealing temperature can result in the reduction of Nd-rich *** annealing temperature can generate the non-defined Nd-rich thin layer between grains.

关键词： Sintered Nd-Fe-B magnets Magnetron sputtering Tb coating Magnetic properties Rare earths

Magnetic properties enhancement of hot-deformed NdFeB magnets by two different methods of CeNdCu diffusion

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Journal of Rare Earths 2020年第12期38卷 1312-1316页

作者： Guibing Shi Zilong Wang Xinyuan Bai Wenlong Yan Yang Luo dunbo yu National Engineering Research Center for Rare Earth Materials GRINM Group Co.Ltd.Beijing 100088China GRIREM Advanced Materials Co. Ltd.Beijing 100088China General Research Institute for Nonferrous Metals Beijing 100088China

Two different ways were used to control the distribution of cerium for the enhancement of *** was by coating CeNdCu in the prepared magnet and annealing to make CeNdCu diffuse into the grain boundary to increase the coercivity,the other was by mixing CeNdCu with initial magnetic powders and then preparing the hot-deformed *** SEM-EDS result indicates that cerium diffuses more easily into the main phase by the mixing way,while cerium is mainly distributed in the grain boundary via the coating *** heat-treatment process may be one of the dominant influencing factors for the distribution of Ce,Multi-steps heat treatment in the mixing way,consisting of hot-pressing,hot-deforming and post heat process,easily introduces Ce into the main phase Nd2 Fe14B,which forms the Ce2 Fe14B shell resulting in the decrease of *** the coating way can ensure uniform dispersion of Ce in the grain boundary,which leads to the high coercivity.

关键词： Hot-deformed magnet Coating Mixing CeNdCu Rare earths

Effect of silane coupling agents on flowability and compressibility of compound for bonded NdFeB magnet

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Journal of Rare Earths 2022年第5期40卷 772-777,I0004页

作者： Xiaowei Zhang Zilong Wang Tianhao Li Shengjie Zhu dunbo yu Wenlong Yan Yang Luo National Engineering Research Center for Rare Earth Materials GRINM Group Co.Ltd.Beijing 100088China GRIREM Advanced Materials Co. Ltd.Beijing 100088China General Research Institute for Nonferrous Metals Beijing 100088China

Based on the difference of the Y-terminal functional group of the silane coupling agent(Y-Si(X)_(3)),four different silane coupling agents were employed to pretreat the surface of the NdFeB *** effects of silane coupling agents on the flowability and compressibility of compounds for preparing bonded NdFeB magnets were *** is indicated that compounds pretreated by silane coupling agents have weaker friction and meshing *** apparent density is increased by 0.3 g/cm^(3 )compared with the compound without silane coupling agent,and the radial crushing strength is significantly increased by about 3-4 *** addition,the epoxy resin is more evenly distributed on the surface of the compounds treated by silane coupling agents observed by scanning electron microscopy,and some agglomerated particles are ***,the compressibility of compounds with silane coupling agents is significantly improved due to the fact that hardening exponents are ***,the addition of silane coupling agents has almost no effect on the magnetic properties of bonded *** special energy was used to manifest the flowability of magnetic powder particles representing the macroscopic performance of the force between powder particles,providing a new direction for the study of the interface compatibility of two-phase or multiphase composite materials.

关键词： Bonded NdFeB magnets Silane coupling agent Flowability Special energy Compressibility Rare earths

Heat Transfer Analysis During "One-Step" Directional Solidification Process for Giant Magnetostrictive Materials

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Journal of Rare Earths 2004年第z2期22卷 183-185页

作者： Li Kuoshe Yang Hongchuan Xu Jing yuan Yongqiang yu dunbo Li Hongwei Grirem Advanced Materials Co. LtdGeneral Research Institute for Nonferrous MetalsBeijing 100088China

By theoretical analysis of heat transfer during the "one-step" directional solidification process, the functional relation between the temperature in solid-liquid interface and its effect factor was studied. The thermal gradient in solid liquid interface and heat transfer coefficient between the samples and surroundings were also calculated. On the basis of the above analysis, some suggestions for improving the thermal gradient in solid-liquid interface were put forward. It will provide a theoretical instruction for preparing high performance giant magnetostrictive materials (GMM).

关键词： directional solidification "one-step"process heat transfer solid-liquid interface thermal gradient

Effects of grain boundary diffusion of PrCu alloy on microstructure and coercivity of hot deformed(Nd,Ce)-Fe-B magnets

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Journal of Rare Earths 2021年第8期39卷 986-992页

作者： Haijun Peng dunbo yu Xinyuan Bai Xiao Lin Yongjun Mao Zilong Wang Yang Luo National Engineering Research Center for Rare Earth Materials CRINM Group Co.Ltd.Beijing 100088China GRIREM Advanced Materials Co. Ltd.Beijing 100088China General Research Institute for Non/errous Metals Beijing 100088China

The technology of using high abundance rare earth element Ce in permanent magnets has attracted many *** this work,the magnetic properties and microstructures of hot deformed(Nd_(1-x)Ce_(x))_(13.8)Fe_(76.1)Co_(4)Ga_(0.5)B_(5.6) magnets and a selective magnet treated with PrCu grain boundary diffusion process(GBDP) were investigated *** is found that Ce is beneficial to improving the plastic deformation ability of NdFeB *** strongest c-axis orientation is achieved in the HD magnets with Ce concentration of x=0.3,resulting in good comprehensive magnetic properties of B_(r)=13.00 kGs,H_(cj)=10.12 kOe,(BH)_(max)=38.42 *** on that,the GBDP was implemented on the magnets with the best orientation using Pr_(68)Cu_(32) ribbons and the magnetic properties of B_(r)=12.87 kGs,H_(cj)=15.65 kOe,(BH)_(max)=37.48 MGOe were *** results of composition distribution and Curie temperature test of the GBDPed magnets illustrate that Pr diffuses into the(Nd,Ce)_(2)(Fe,Co)_(14)B grains to substitute Ce,which not only improves the Curie temperature of the grains,but also enhances the magnetic performance of the *** GBDP,the thermal stability of magnets has also been improved.

关键词： Nd-Ce-Fe-B GBDP Hot deformation Magnetic properties Microstructure Rare earths

Structure and hard magnetic properties of TbCu_7-type SmFe_(8.95-x)Ga_(0.26)Nb_x nitrides

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Journal of Rare Earths 2018年第2期36卷 165-169页

作者： Wenlong Yan Ningtao Quan Yang Luo dunbo yu Zilong Wang Guiyong Wu Kun Zhang National Engineering Research Center for Rare Earth Materials General Research Institute for Nonferrous Metals and Grirem Advanced Materials Co. Ltd. Key Laboratory of Microgravity (National Microgravity Laboratory) Institute of Mechanics Chinese Academy of Sciences

Nanocrystalline SmFe_（8.95-x）Ga_（0.26）Nb_xN_δ（x=0, 0.1, 0.2, 0.3） were prepared using rapid-quenching,annealing and nitriding. The magnetic properties and crystal structures were systematically studied under various wheel velocities to investigate the influence of Nb doping for the compounds. It is found that TbCu7-type structure is able to be obtained even though the wheel velocity is reduced to 20 m/s（x = 0.3）. An significant increase（△T_c=70 ℃） of the Curie temperature is obtained with Nb doping at x = 0.1 due to the lattice expansion revealed by Rietveld analysis. The optimum coercivity with the value H_（cj） of 810 kA/m is achieved at x = 0.2 in the nitrides, in which a reasonable distribution of grain sizes of both TbCu_7-type SmFe_9 N_δ and α-Fe can be found. However, an excess of Nb doping may lead to the increase of the weight fraction of α-Fe, which in turn deteriorates the magnetic properties.

关键词： Rapid-quenching SmFe8.95-xGa0.26Nbx alloy TbCu7-type structure Magnetic properties

Effects of cerium substitution on phase components, microstructures and magnetic properties of Nd-Fe-Ti-B alloy

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Journal of Rare Earths 2019年第8期37卷 861-864,I0003页

作者： Haijun Peng Yang Luo Yakun Dou Xinyuan Bai Wenlong Yan dunbo yu yuanfei Yang Shulin Diao National Engineering Research Center for Rare Earth Materials General Research Institute for Nonferrous MetalsGrirem Advanced Materials Co.Ltd.Beijing 100088China Tianhe(Baotou)Advanced Tech Magnet Co. Ltd.Baotou 014010China

(Nd(1-x)Cex)(12)Fe(77)Ti5B6(x=0,0.2,0.3,0.4,0.6,0.8)alloys were prepared by melt-spinning and annealing *** phase constitutions,microstructures and magnetic properties were investigated by powder X-ray diffraction(XRD),a differential scanning calorimeter(DSC),a vibrating sample magnetometer(VSM)and a transmission electron microscope(TEM).It is found that with the increase of Ce content,the coercivity of the(Nd(1-x)Cex)(12)Fe(77)Ti5B6 alloys reaches maximum first and then *** maximum coercivity reaches 18.5 kOe obtained in the sample of 20%Ce substituted which is 34%higher than the Ce-free *** results reveal that the micro structure refinement effect is responsible for the coercivity *** phenomenon implies that in some cases,Ce and Ti co-doping is more beneficial to improving of the coercivity than Ti single doping in Nd-Fe-B *** further Ce addition,magnetic properties deteriorate due to the formation of CeFe2 and TbCu7-type phases.

关键词： Melt spun Nd-Ce-Fe-Ti-B Coercivity Microstructure refinement Magnetic Rare earths

Magnetostrictive properties and detection efficiency of TbDyFe/FeCo composite materials for nondestructive testing

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Journal of Rare Earths 2019年第2期37卷 166-170页

作者： Liangliang Zhu Kuoshe Li Yang Luo dunbo yu Zilong Wang Guiyong Wu Jiajun Xie Zhifeng Tang National Engineering Research Center for Rare Earth Materials General Research Institute for Nonferrous Metals Grirem Advanced Materials Co. Ltd. Institute of Advanced Digital Technologies and Instrumentation Zhejiang University

In order to develop a highly sensitive material for nondestructive testing(NDT),(Tb_(0.3) Dy_(0.7))Fe_(1.95) thin films were deposited on FeCo substrates at room temperature by magnetron sputtering and *** magnetostrictive properties and the detection efficiency of the composite films were *** demonstrate that the detection efficiency roughly shows regular consistency with the magnetostrictive strain of the TbDyFe films. Heat treatment has a great effect on the crystalline state and the magnetostrictive strain of the composite materials. The as-deposited(Tb_(0.3) Dy_(0.7))Fe_(1.95) films are amorphous, and the saturation magnetostriction(ls) is only 90 ppm. However, the nanostructured crystalline REFe2 is partially separated out in amorphous matrix after annealing at 600C for 1 h, and the ls increases to 265 ppm. Simultaneously, the detection efficiency of the composite materials is obviously improved compared to that of the as-deposited films. The detection signal of traditional FeCo strip is0.4 V at the excitation power of 1.0 P and frequency of 128 kHz and that of the strip increases significantly by depositing one layer of(Tb_(0.3) Dy_(0.7))Fe_(1.95) film. The detection signal of the composite material annealed at 600C is the best, even reaching saturation value of 2.5 V(1.0 P, 128 kHz). The results may provide us with a method for preparing new materials for NDT.

关键词： Magnetron sputtering Magnetostrictive thin film Ultrasound guided wave Nondestructive testing Rare earths

Magnetic properties and magnetization mechanism of anisotropic NdFeB/SmFeN hybrid bonded magnets prepared with different coercivity NdFeB powders

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Journal of Rare Earths 2023年第9期41卷 1353-1359,I0003页

作者： Qisong Luo Yang Luo Zilong Wang Haijun Peng Wenlong Yan Wenjian Yan Tianhao Li Shengjie Zhu dunbo yu National Engineering Research Center for Rare Earth GRINM Group Co.LtdBeijing 100088China GRIREM Advanced Materials Co. LtdBejing 100088China General Research Institute for Nonferrous Metals Beijing 100088China

Anisotropic NdFeB/SmFeN hybrid bonded magnets were prepared by warm compaction process under an orientation magnetic field of 22 kOe,mixing with anisotropic SmFeN powders in different addition and HDDR-NdFeB powders in different *** the addition of 20 wt% SmFeN,the density and remanence of hybrid magnets increase from 5.58 g/cm~3,8.4 kGs to 6.02 g/cm~3,9.0 kGs,*** as the addition amount of SmFeN powders varies from 20 wt% to 40 wt%,the maximum energy product changes less than 0.5 *** addition,the magnetization process and the interactions between two powders were *** is found that the magnetization process of anisotropic NdFeB powders shows distinction in different initial *** addition of SmFeN powders promotes the rotation of NdFeB powders together with applied field,which is beneficial to the degree of alignment of NdFeB *** of the micron-sized long range coupling effect,the coercivity of hybrid magnets decreases slowly with the increase of low coercivity ***,the magnetization process of hybrid magnets is different from pure magnets,it increases rapidly at low field and then slowly,next leads to rapidity again and achieves the saturation magnetization finally.

关键词： Anisotropic hybrid bonded magnet NdFeB/SmFeN Coupling effect Magnetization process Coercivity Rare earths