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| 1 | Effects of cerium substitution on phase components, microstructures and magnetic properties of Nd-Fe-Ti-B alloy显示文摘(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 techniques.The 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 decreases.The maximum coercivity reaches 18.5 kOe obtained in the sample of 20%Ce substituted which is 34%higher than the Ce-free sample.TEM results reveal that the micro structure refinement effect is responsible for the coercivity improvement.This 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 alloys.With further Ce addition,magnetic properties deteriorate due to the formation of CeFe2 and TbCu7-type phases. | Haijun Peng Yang Luo Yakun Dou Xinyuan Bai Wenlong Yan Dunbo Yu Yuanfei Yang Shulin Diao | 2019 | Journal of Rare Earths2019，37，8： | 4 |
| 2 | Magnetostrictive properties and detection efficiency of TbDyFe/FeCo composite materials for nondestructive testing显示文摘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 annealed.The magnetostrictive properties and the detection efficiency of the composite films were investigated.Results 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. | Liangliang Zhu Kuoshe Li Yang Luo Dunbo Yu Zilong Wang Guiyong Wu Jiajun Xie Zhifeng Tang | 2019 | Journal of Rare Earths2019，37，2： | 3 |
| 3 | Magnetic properties enhancement of hot-deformed NdFeB magnets by two different methods of CeNdCu diffusion显示文摘Two different ways were used to control the distribution of cerium for the enhancement of coercivity.One 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 magnet.The 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 way.The 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 HA.But the coating way can ensure uniform dispersion of Ce in the grain boundary,which leads to the high coercivity. | Guibing Shi Zilong Wang Xinyuan Bai Wenlong Yan Yang Luo Dunbo Yu | 2020 | Journal of Rare Earths2020，38，12： | 3 |
| 4 | Effect of niobium substitution on microstructures and thermal stability of TbCu7-type Sm-Fe-N magnets显示文摘This paper reports crystal structures, magnetic properties and thermal stability of TbCu7-type Sm_(8.5)Fe_((85.8-x)Co_(4.5)Zr_(1.2)Nb_x(x = 0-1.8) melt-spun compounds and their nitrides, investigated by means of X-ray diffraction, vibrating sample magnetometer, flux meter and transmission electron microscope. It is found that the lattice parameter ratio c/a of TbCu_7-type crystal structure increases with Nb substitution, which indicates that the Nb can increase the stability of the metastable phase in the Sm-Fe ribbons. Nb substitution impedes the formation of magnetic soft phase a-Fe in which reversed domains initially form during the magnetization reversal process. Meanwhile, Nb substitution refines grains and leads to homogeneous micro structure with augmented grain boundaries. Thus the exchange coupling pining field is enhanced and irreversible domain wall propagation gets suppressed. As a result, the magnetic properties are improved and the irreversible flux loss of magnets is notably decreased. A maximum value 771.7 kA/m of the intrinsic coercivity H_(cj) is achieved in the 1.2 at% substituted samples.The irreversible flux loss for 2 h exposure at 120 ℃ declines from 8.26% for Nb-free magnets to 6.32% for magnets with 1.2 at% Nb substitution. | Guiyong Wu Hongwei Li Dunbo Yu Kuoshe Li Wenlong Yan Chao Yuan Liang Sun Yang Luo Kun Zhang | 2018 | Journal of Rare Earths2018，36，3： | 2 |
| 5 | Magnetic properties and microstructures of terbium coated and grain boundary diffusion treated sintered Nd-Fe-B magnets by magnetron sputtering显示文摘Tb coating on the surface of commercial sintered Nd-Fe-B magnet was prepared by DC magnetron sputtering.The secondary heat treatment was used to regulate the microstructure for the enhancement of coercivity,namely diffusion treatment and annealing treatment.The 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 temperature.Lower diffusion temperature results in insufficient diffusion of Tb element.Higher diffusion temperature can lead to the main phase grain growth,the decrease of Nd-rich phase,and forming holes in the magnet.On the other hand,500℃is the optimal annealing temperature.Lower annealing temperature can result in the reduction of Nd-rich phase.Higher annealing temperature can generate the non-defined Nd-rich thin layer between grains. | Wei Zhu Yang Luo Zilong Wang Xinyuan Bai Haijun Peng Dunbo Yu | 2021 | Journal of Rare Earths2021，39，2： | 2 |
| 6 | Effects of grain boundary diffusion of PrCu alloy on microstructure and coercivity of hot deformed(Nd,Ce)-Fe-B magnets显示文摘The technology of using high abundance rare earth element Ce in permanent magnets has attracted many concerns.In 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 systematically.It is found that Ce is beneficial to improving the plastic deformation ability of NdFeB magnets.The 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 MGOe.Based 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 obtained.The 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 magnets.Through GBDP,the thermal stability of magnets has also been improved. | Haijun Peng Dunbo Yu Xinyuan Bai Xiao Lin Yongjun Mao Zilong Wang Yang Luo | 2021 | Journal of Rare Earths2021，39，8： | 1 |
| 7 | Effect of Nb doping on microstructure and magnetic properties of hot-deformed Nd-Fe-B magnets with Nd-Cu eutectic diffusion显示文摘To restrict grain growth in coarse grain regions caused by the diffusion of Nd-Cu eutectic alloys,the Nb element was introduced into the precursor alloy to regulate the microstructure of melt-spun powder and die-upset magnets.The magnetic properties and thermal stability of die-upset magnets were appreciably improved through the addition of Nb.For the Nb-doped diffusion die-upset magnet,the grains inside the ribbons were refined and the coarse non-oriented surface crystallite got suppressed on the interface of ribbons during the hot-deformation process to form the anisotropic magnet.Moreover,Nd gathers at the intergranular phases,which is considered to enforce domain wall pinning force.The Nb-modified microstructure is advantageous to thermal stability and coercivity enhancement.High-resolution transmission electron microscopy images revealed that the Nb element gathered on the grain boundary and triple grain boundary to form c-Nb and h-Nb Fe B to hinder the grain growth during the hot-deformation process,which led to direct enhancement in the coercivity.Furthermore,the c-Nb and h-Nb Fe B are nonmagnetic phases that strengthened the magnetic isolation.However,the h-Nb Fe B precipitated from the hard magnetic phase and formed crystal defects which led to remanence deterioration. | Tingting Song Xin Li Xu Tang Wenzong Yin Yang Luo Dunbo Yu Wenlong Yan Jinyun Ju Renjie Chen Aru Yan | 2022 | Journal of Materials Science & Technology2022，，27： | 1 |
| 8 | Preparation of Giant Mangetostrictive Sintered Compacts by Powder Metallurgy显示文摘Powder metallurgy technique was applied to prepare rare earth giant magnetostrictive materials. This preparation process consists of casted Tb_ 0.30Dy_ 0.70Fe_ 1.80 alloy, which is pulverized by ball mill, aligned in magnetic field, compacted and sintered in inertial atmosphere. The experimental results indicate that when the magnetic field is 240 kA·m -1, the sample with particle size less than 0.147 mm being compacted in magnetic field exhibits 1613×10 -3 magnetostriction under a compressive pre-stress 8.0 MPa after being sintered at 1200 ℃ for 2 h and annealed at 950 ℃ for 24 h. | Xu Jianlin Li Hongwei Yang Hongchuan Zhang Shirong Li Kuoshe Yu Dunbo | 2006 | Journal of Rare Earths2006，24，3： | 1 |
| 9 | Magnetic properties and magnetization mechanism of anisotropic NdFeB/SmFeN hybrid bonded magnets prepared with different coercivity NdFeB powders显示文摘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 coercivity.With 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,respectively.And as the addition amount of SmFeN powders varies from 20 wt% to 40 wt%,the maximum energy product changes less than 0.5 MGOe.In addition,the magnetization process and the interactions between two powders were studied.It is found that the magnetization process of anisotropic NdFeB powders shows distinction in different initial states.The addition of SmFeN powders promotes the rotation of NdFeB powders together with applied field,which is beneficial to the degree of alignment of NdFeB powders.Because of the micron-sized long range coupling effect,the coercivity of hybrid magnets decreases slowly with the increase of low coercivity SmFeN.Meanwhile,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. | Qisong Luo Yang Luo Zilong Wang Haijun Peng Wenlong Yan Wenjian Yan Tianhao Li Shengjie Zhu Dunbo Yu | 2023 | Journal of Rare Earths2023，41，9： | 0 |
| 10 | Anomalous Magnetic Behavior in Phase-separated La0.5 Sr0.5 MnO3 +δ Films显示文摘(001)La0.5 Sr0.5MnO3 +δ films on (001)LaA1O3 substrates were prepared by using a RF magnetron sputtering with powder target.At low temperature, the films exhibit two phase coexistence, which means that ferromagnetic (FM) clusters are embedded in antiferromagnetic (AFM) matrix.Moreover, a shift in hysteresis loop is unexpectedly observed in this inhomogeneous system.We suggest that the anomalous hysteresis loop may result from the unidirectional exchange anisotropy at the interface between AFM and FM clusters. | Yu Dunbo Ying Qiming Zhang Guocheng Li Tong Du Yongsheng Wang Bo Yan Hui | 2004 | Journal of Rare Earths2004，22，z1： | 0 |
| 11 | Structure and hard magnetic properties of TbCu_7-type SmFe_(8.95-x)Ga_(0.26)Nb_x nitrides显示文摘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. | Wenlong Yan Ningtao Quan Yang Luo Dunbo Yu Zilong Wang Guiyong Wu Kun Zhang | 2018 | Journal of Rare Earths2018，36，2： | 0 |
| 12 | Surface and internal magnetic domain structures of Fe-Ga alloy rods显示文摘The magnetic domain structures of the 100 oriented Fe 81 Ga 19 polycrystalline alloys with rapid quenching(RQ) and post-annealing(PA) thermal treatments are investigated by using magnetic force microscopy(MFM).The surfaces of the RQ alloy rods take on the dendritic domains after undergoing a standard mechanical polishing.While after PA processing,the distinct domain structures are observed at different temperatures.The wide stripe-like domain patterns appear in the surface of those PA rods at 550°C while the ramous domains remain at 400°C annealing.X-ray diffraction patterns indicate that a thin iron layer is formed on the surface of the specimens annealed at higher temperature.The soft magnetic iron layer,actually acting as a shield for the stray fields emerging from the internal magnetic structures underneath,brings about the presentation of the wide internal domains. | HAN YuNan LI YongSheng HAN XiuFeng YU DunBo | 2013 | Science China(Technological Sciences)2013，56，1： | 0 |
| 13 | Heat Transfer Analysis During 'One-Step' Directional Solidification Process for Giant Magnetostrictive Materials显示文摘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). | Li Kuoshe Yang Hongchuan Xu Jing Yuan Yongqiang Yu Dunbo Li Hongwei | 2004 | Journal of Rare Earths2004，22，z2： | 0 |
| 14 | Effect of MgCl_(2) on electrophoretic deposition of TbF_(3) powders on Nd-Fe-B sintered magnet显示文摘Using electrophoretic deposition(EPD)method,the TbF_(3)powders were deposited on the surface of sintered Nd-Fe-B magnets,and the effects of MgCl_(2)on electrophoretic deposition and grain boundary diffusion were investigated.The results show that addition of 5 wt%MgCl_(2)can significantly improve the EPD efficiency and improve the adhesion of the coating by releasing local stress through the formation of special gully morphology.Combining with Biesheuvel equation,the effects of suspension concentration,voltage and time on EPD amount were studied.The Biesheuvel equation can be simplified asγ=AUSct/L,and A(=0.0141-0.0144)in this experiment was calculated to achieve the quantitative calculation of EPD amount.After heat treatment of 875℃×10 h+500℃×1 h,the coercivity of 48H(7 mm)sintered magnet with 0.3 wt%TbF_(3)increases from 18.5 to 22.4 kOe,with an increase of 21.1%.The core-shell structure was observed by a back-scattered scanning electron microscope(BSE-SEM),which proves that the addition of MgCl_(2)has no adverse effect on the grain boundary diffusion of Nd-Fe-B sintered magnets. | Chen Wang Yang Luo Zilong Wang Wenlong Yan Yanyan Zhao Ningtao Quan Haijun Peng Kaiwen Wu Yuehua Ma Chunlei Zhao Dunbo Yu | 2023 | Journal of Rare Earths2023，41，5： | 0 |
| 15 | Effect of silane coupling agents on flowability and compressibility of compound for bonded NdFeB magnet显示文摘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 powders.The effects of silane coupling agents on the flowability and compressibility of compounds for preparing bonded NdFeB magnets were studied.It is indicated that compounds pretreated by silane coupling agents have weaker friction and meshing force.The 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 times.In 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 produced.Also,the compressibility of compounds with silane coupling agents is significantly improved due to the fact that hardening exponents are reduced.However,the addition of silane coupling agents has almost no effect on the magnetic properties of bonded magnets.The 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. | Xiaowei Zhang Zilong Wang Tianhao Li Shengjie Zhu Dunbo Yu Wenlong Yan Yang Luo | 2022 | Journal of Rare Earths2022，40，5： | 0 |
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