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Toward understanding the microstructure characteristics,phase selection and magnetic properties of laser additive manufactured Nd-Fe-B permanent magnets 被引量:1
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作者 Bo Yao Nan Kang +6 位作者 Xiangyu Li Dou Li Mohamed EL Mansori Jing Chen Haiou Yang Hua Tan Xin Lin 《International Journal of Extreme Manufacturing》 SCIE EI CAS CSCD 2024年第1期277-294,共18页
Nd-Fe-B permanent magnets play a crucial role in energy conversion and electronic devices.The essential magnetic properties of Nd-Fe-B magnets,particularly coercivity and remanent magnetization,are significantly infue... Nd-Fe-B permanent magnets play a crucial role in energy conversion and electronic devices.The essential magnetic properties of Nd-Fe-B magnets,particularly coercivity and remanent magnetization,are significantly infuenced by the phase characteristics and microstructure.In this work,Nd-Fe-B magnets were manufactured using vacuum induction melting(VIM),laser directed energy deposition(LDED)and laser powder bed fusion(LPBF)technologies.Themicrostructure evolution and phase selection of Nd-Fe-B magnets were then clarified in detail.The results indicated that the solidification velocity(V)and cooling rate(R)are key factors in the phase selection.In terms of the VIM-casting Nd-Fe-B magnet,a large volume fraction of theα-Fe soft magnetic phase(39.7 vol.%)and Nd2Fe17Bxmetastable phase(34.7 vol.%)areformed due to the low R(2.3×10-1?C s-1),whereas only a minor fraction of the Nd2Fe14B hard magnetic phase(5.15 vol.%)is presented.For the LDED-processed Nd-Fe-B deposit,although the Nd2Fe14B hard magnetic phase also had a low value(3.4 vol.%)as the values of V(<10-2m s-1)and R(5.06×103?C s-1)increased,part of theα-Fe soft magnetic phase(31.7vol.%)is suppressed,and a higher volume of Nd2Fe17Bxmetastable phases(47.5 vol.%)areformed.As a result,both the VIM-casting and LDED-processed Nd-Fe-B deposits exhibited poor magnetic properties.In contrast,employing the high values of V(>10-2m s-1)and R(1.45×106?C s-1)in the LPBF process resulted in the substantial formation of the Nd2Fe14B hard magnetic phase(55.8 vol.%)directly from the liquid,while theα-Fe soft magnetic phase and Nd2Fe17Bxmetastable phase precipitation are suppressed in the LPBF-processed Nd-Fe-B magnet.Additionally,crystallographic texture analysis reveals that the LPBF-processedNd-Fe-B magnets exhibit isotropic magnetic characteristics.Consequently,the LPBF-processed Nd-Fe-B deposit,exhibiting a coercivity of 656 k A m-1,remanence of 0.79 T and maximum energy product of 71.5 k J m-3,achieved an acceptable magnetic performance,comparable to other additive manufacturing processed Nd-Fe-B magnets from MQP(Nd-lean)Nd-Fe-Bpowder. 展开更多
关键词 laser additive manufacturing(LAM) Nd-Fe-B permanent magnets numerical simulation microstructure magnetic properties
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Enhanced soft magnetic properties of SiO_(2)-coated FeSiCr magnetic powder cores by particle size effect
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作者 Mingyue Ge Likang Xiao +6 位作者 Xiaoru Liu Lin Pan Zhangyang Zhou Jianghe Lan Zhengwei Xiong Jichuan Wu Zhipeng Gao 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第10期405-412,共8页
It has been known that metal FeSiCr powders with large average particle sizes have been typically employed to prepare magnetic powder cores(SMCs),with few studies reported on the influence of magnetic properties for o... It has been known that metal FeSiCr powders with large average particle sizes have been typically employed to prepare magnetic powder cores(SMCs),with few studies reported on the influence of magnetic properties for original powders with various average particle sizes less than 10m.In this work,SiO_(2)-coated FeSiCr SMCs with different small particle sizes were synthesized using the sol-gel process.The contribution of SiO_(2)coating amount and voids to the soft magnetic properties was elaborated.The mechanism was revealed such that smaller particle sizes with less voids could be beneficial for reducing core loss in the SMCs.By optimizing the core structure,permeability and magnetic loss of 26 and 262 kW/cm^(3)at 100 kHz and 50 mT were achieved at a particle size of 4.8m and ethyl orthosilicate addition of 0.1 mL/g.The best DC stacking performance,reaching 87%,was observed at an ethyl orthosilicate addition rate of 0.25 mL/g under 100 Oe.Compared to other soft magnetic composites(SMCs),the FeSiCr/SiO_(2)SMCs exhibit significantly reduced magnetic loss.It further reduces the magnetic loss of the powder core,providing a new strategy for applications of SMCs at high frequencies. 展开更多
关键词 FeSiCr SiO_(2) size effect magnetic properties DC superposition
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Effect of In doping on the evolution of microstructure,magnetic properties and corrosion resistance of NdFeB magnets
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作者 李豫豪 范晓东 +8 位作者 贾智 范璐 丁广飞 刘新才 郭帅 郑波 曹帅 陈仁杰 闫阿儒 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第3期623-629,共7页
The grain boundary phase affects the magnetic properties and corrosion resistance of sintered NdFeB magnets.In this work,a small amount of In was added to NdFeB magnets by induction melting to systematically investiga... The grain boundary phase affects the magnetic properties and corrosion resistance of sintered NdFeB magnets.In this work,a small amount of In was added to NdFeB magnets by induction melting to systematically investigate its effect on the evolution of the microstructure,magnetic properties and corrosion resistance of NdFeB magnets.Microstructural analysis illustrated that minor In addition generated more grain boundary phases and an abundant amorphous phase at the triple-junction grain boundary.While the addition of In failed to enhance the magnetic isolation effect between adjacent matrix grains,its incorporation fortuitously elevated the electrochemical potential of the In-containing magnets.Besides,during corrosion,an In-rich precipitate phase formed,hindering the ingress of the corrosive medium into the magnet.Consequently,this significantly bolstered the corrosion resistance of the sintered NdFeB magnets.The phase formation,magnetic properties and corrosion resistance of In-doped NdFeB magnets are detailed in this work,which provides new prospects for the preparation of high-performance sintered NdFeB magnets. 展开更多
关键词 In-doping NdFeB magnets magnetic properties corrosion resistance
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Impact of Co^(2+)substitution on structure and magnetic properties of M-type strontium ferrite with different Fe/Sr ratios
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作者 Yang Sun Ruoshui Liu +1 位作者 Huayang Gong Baogen Shen 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第10期427-433,共7页
Ion substitution has significantly improved the performance of ferrite magnets,and cobalt remains a key area of research.Studies on the mechanism of Co^(2+)in strontium ferrite,especially SrFe_(2n-x)Co_(x)O_(19-d)(n=6... Ion substitution has significantly improved the performance of ferrite magnets,and cobalt remains a key area of research.Studies on the mechanism of Co^(2+)in strontium ferrite,especially SrFe_(2n-x)Co_(x)O_(19-d)(n=6.1-5.4;x=0.05-0.20)synthesized using the ceramic method,showed that Co^(2+)preferentially enters the lattice as the Fe/Sr ratio decreases.This results in a decrease in the lattice constants a and c due to oxygen vacancies and iron ion deficiency.The impact of Co substitution on morphology is minor compared to the effect of the Fe/Sr ratio.As the Fe/Sr ratio decreases and the Co content increases,the saturation magnetization decreases.The magnetic anisotropy field exhibits a nonlinear change,generally increasing with higher Fe/Sr ratios and Co content.These changes in the performance of permanent magnets are attributed to the absence of Fe^(3+)ions at the 12k+2a and 2b sites and the substitution of Co^(2+)at the 2b site.This suggests that by adjusting the Fe/Sr ratio and appropriate Co substitution,the magnetic anisotropy field of M-type strontium ferrite can be effectively optimized. 展开更多
关键词 HEXAFERRITE Co substitution Raman spectra magnetic properties
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Effect of Y element on atomic structure, glass forming ability,and magnetic properties of FeBC alloy
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作者 肖晋桦 丁大伟 +3 位作者 李琳 孙奕韬 李茂枝 汪卫华 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第7期440-446,共7页
The atomic structure of amorphous alloys plays a crucial role in determining both their glass-forming ability and magnetic properties. In this study, we investigate the influence of adding the Y element on the glass-f... The atomic structure of amorphous alloys plays a crucial role in determining both their glass-forming ability and magnetic properties. In this study, we investigate the influence of adding the Y element on the glass-forming ability and magnetic properties of Fe_(86-x)Y_xB_7C_7(x = 0, 5, 10 at.%) amorphous alloys via both experiments and ab initio molecular dynamics simulations. Furthermore, we explore the correlation between local atomic structures and properties. Our results demonstrate that an increased Y content in the alloys leads to a higher proportion of icosahedral clusters, which can potentially enhance both glass-forming ability and thermal stability. These findings have been experimentally validated. The analysis of the electron energy density and magnetic moment of the alloy reveals that the addition of Y leads to hybridization between Y-4d and Fe-3d orbitals, resulting in a reduction in ferromagnetic coupling between Fe atoms. This subsequently reduces the magnetic moment of Fe atoms as well as the total magnetic moment of the system, which is consistent with experimental results. The results could help understand the relationship between atomic structure and magnetic property,and providing valuable insights for enhancing the performance of metallic glasses in industrial applications. 展开更多
关键词 Fe-based amorphous alloy ab initio molecular dynamic simulation glass-forming ability magnetic properties
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First‑principles study on electronic structure,optical and magnetic properties of rare earth elements X(X=Sc,Y,La,Ce,Eu)doped with two‑dimensional GaSe
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作者 QIU Shenhao XIAO Qingquan +1 位作者 TANG Huazhu XIE Quan 《无机化学学报》 SCIE CAS CSCD 北大核心 2024年第11期2250-2258,共9页
The electronic structure,magnetic,and optical properties of two-dimensional(2D)GaSe doped with rare earth elements X(X=Sc,Y,La,Ce,Eu)were calculated using the first-principles plane wave method based on den-sity funct... The electronic structure,magnetic,and optical properties of two-dimensional(2D)GaSe doped with rare earth elements X(X=Sc,Y,La,Ce,Eu)were calculated using the first-principles plane wave method based on den-sity functional theory.The results show that intrinsic 2D GaSe is a p-type nonmagnetic semiconductor with an indi-rect bandgap of 2.6611 eV.The spin-up and spin-down channels of Sc-,Y-,and La-doped 2D GaSe are symmetric,they are non-magnetic semiconductors.The magnetic moments of Ce-and Eu-doped 2D GaSe are 0.908μ_(B)and 7.163μ_(B),which are magnetic semiconductors.Impurity energy levels appear in both spin-up and spin-down chan-nels of Eu-doped 2D GaSe,which enhances the probability of electron transition.Compared with intrinsic 2D GaSe,the static dielectric constant of the doped 2D GaSe increases,and the polarization ability is strengthened.The ab-sorption spectrum of the doped 2D GaSe shifts in the low-energy direction,and the red-shift phenomenon occurs,which extends the absorption spectral range.The optical reflection coefficient of the doped 2D GaSe is improved in the low energy region,and the improvement of Eu-doped 2D GaSe is the most obvious. 展开更多
关键词 first principle two-dimensional GaSe electronic structure magnetic property optical property
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First-principles calculations of Ni–(Co)–Mn–Cu–Ti all-d-metal Heusler alloy on martensitic transformation,mechanical and magnetic properties 被引量:2
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作者 Huaxin Qi Jing Bai +7 位作者 Miao Jin Jiaxin Xu Xin Liu Ziqi Guan Jianglong Gu Daoyong Cong Xiang Zhao Liang Zuo 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2023年第5期930-938,共9页
The martensitic transformation,mechanical,and magnetic properties of the Ni_(2)Mn_(1.5-x)Cu_(x)Ti_(0.5) (x=0.125,0.25,0.375,0.5) and Ni_(2-y)Co_(y)Mn_(1.5-x)Cu_(x)Ti_(0.5)[(x=0.125,y=0.125,0.25,0.375,0.5) and (x=0.125... The martensitic transformation,mechanical,and magnetic properties of the Ni_(2)Mn_(1.5-x)Cu_(x)Ti_(0.5) (x=0.125,0.25,0.375,0.5) and Ni_(2-y)Co_(y)Mn_(1.5-x)Cu_(x)Ti_(0.5)[(x=0.125,y=0.125,0.25,0.375,0.5) and (x=0.125,0.25,0.375,y=0.625)]alloys were systematically studied by the first-principles calculations.For the formation energy,the martensite is smaller than the austenite,the Ni–(Co)–Mn–Cu–Ti alloys studied in this work can undergo martensitic transformation.The austenite and non-modulated (NM) martensite always present antiferromagnetic state in the Ni_(2)Mn_(1.5-x)Cu_(x)Ti_(0.5) and Ni_(2-y)Co_(y)Mn_(1.5-x)Cu_(x)Ti_(0.5) (y<0.625) alloys.When y=0.625 in the Ni_(2-y)Co_(y)Mn_(1.5-x)Cu_(x)Ti_(0.5) series,the austenite presents ferromagnetic state while the NM martensite shows antiferromagnetic state.Cu doping can decrease the thermal hysteresis and anisotropy of the Ni–(Co)–Mn–Ti alloy.Increasing Mn and decreasing Ti content can improve the shear resistance and normal stress resistance,but reduce the toughness in the Ni–Mn–Cu–Ti alloy.And the ductility of the Co–Cu co-doping alloy is inferior to that of the Ni–Mn–Cu–Ti and Ni–Co–Mn–Ti alloys.The electronic density of states was studied to reveal the essence of the mechanical and magnetic properties. 展开更多
关键词 Ni–Mn–Ti-based all-d-metal Heusler alloys first-principles calculations mechanical properties martensitic transformation magnetic properties
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Low Temperature Heat Capacity of Zn Substituted Cobalt Ferrite Nanosphere:The Relation between Magnetic Properties and Microstructure
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作者 YUAN Meng GU Xiaojie +4 位作者 FU Jie WANG Shaoxu SHI Quan TAN Zhicheng XU Fen 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS CSCD 2023年第5期984-995,共12页
Co_((1-x))ZnxFe_(2)O_(4)nanospheres(x=0,0.5,0.8)with a unidirectional cubic spinel structure were prepared by a solvothermal method.By using a range of theoretical and empirical models,the experimental heat capacity v... Co_((1-x))ZnxFe_(2)O_(4)nanospheres(x=0,0.5,0.8)with a unidirectional cubic spinel structure were prepared by a solvothermal method.By using a range of theoretical and empirical models,the experimental heat capacity values were fitted as a function of temperature over a suitable temperature range to explain the possible relationship between the magnetic properties and microstructure of the nanospheres.As a result,at a low temperature(T<10 K),the parameter Bfswdecreases with increasing Zn concentration,implying that the exchange interaction between A and B sites decreases.At a relatively high temperature(T>50 K),the Debye temperature decreases with increasing Zn concentration,which is due to the weakening of the interatomic bonding force after the addition of non-magnetic materials to the Co Fe_(2)O_(4)spinel ferrite. 展开更多
关键词 Co-Zn spinal ferrite nanospheres magnetic properties heat capacity thermodynamic functions PPMS
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Influence of Phosphorus Content and Magnetic Annealing on Soft Magnetic Properties of Electrodeposited Amorphous FeMnP Alloy Films
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作者 Vincent Izerimana Lei Ma +2 位作者 Huiliang Wu Jianbo Wang Qingfang Liu 《Journal of Materials Science and Chemical Engineering》 CAS 2023年第1期1-14,共14页
In this work, we investigated the influence of phosphorus and magnetic anneal on the soft magnetic properties of electrodeposited FeMnP alloy films prepared by changing sodium hypophosphite concentrations. X-ray diffr... In this work, we investigated the influence of phosphorus and magnetic anneal on the soft magnetic properties of electrodeposited FeMnP alloy films prepared by changing sodium hypophosphite concentrations. X-ray diffraction radiation patterns showed an amorphous structure of electrodeposited alloy films. The saturation magnetization and coercivity value decreased from 586 emu/cc to 346 emu/cc, and 52 Oe to 18 Oe, with the P content increased, respectively. The absorption resonance peak became broad as the P content increased, and the natural resonance frequency decreased from 1.8 GHz to 0.6 GHz, with the P content increasing. Magnetic annealing of samples reduced the magnetic damping, and natural resonance frequency increased by about 1.8 GHz and 3.5 GHz for the sample with lower and higher P content. The film structure with lower P content changed at 300&#730;C, while the structure remains unchanged for the films with higher P content. Thus, the crystallization temperature could depend on the P content in the film. FeMnP alloy films could be used in high-frequency devices. 展开更多
关键词 PHOSPHORUS magnetic Annealing Soft magnetic Property Natural Resonance Frequency
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Microstructure and magnetic properties of Ni-Zn ferrites doped with MnO_2 被引量:2
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作者 苏桦 张怀武 +1 位作者 唐晓莉 荆玉兰 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2011年第1期109-113,共5页
To improve the performance of Ni-Zn ferrites for power field use,the influence of MnO2 additive on the properties of Ni-Zn ferrites was investigated by the conventional powder metallurgy.The results show that MnO2 doe... To improve the performance of Ni-Zn ferrites for power field use,the influence of MnO2 additive on the properties of Ni-Zn ferrites was investigated by the conventional powder metallurgy.The results show that MnO2 does not form a visible second phase in the doping mass fraction range of(0-2.0%).The average grain size,sintering density and real permeability gradually decrease with the increase of the MnO2 content.And the DC resistivity continuously increases with the increase of MnO2 content.The saturation magnetization(magnetic moment in unit mass) first increases slightly when mass fraction of MnO2 is less than 0.4% MnO2,and then gradually decreases with increasing the MnO2 mass fraction due to the exchange interaction of the cations.When the excitation frequency is less than 1 MHz,the power loss(Pcv) continuously increases with increasing the MnO2 content due to the decrease of average grain size.However,when the excitation frequency exceeds 1 MHz,eddy current loss gradually becomes the predominant contribution to Pcv.And the sample with a higher resistivity favors a lower Pcv,except for the sample with 2.0% MnO2.The sample without additive has the best Pcv when worked at frequencies less than 1 MHz;and the sample with 1.6% MnO2 additive has the best Pcv when worked at frequencies higher than 1 MHz. 展开更多
关键词 Ni-Zn ferrite MNO2 DOPING magnetic properties
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Thermal stability,crystallization behavior,Vickers hardness and magnetic properties of Fe-Co-Ni-Cr-Mo-C-B-Y bulk metallic glasses 被引量:2
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作者 韩佳甲 王翠萍 +1 位作者 寇生中 刘兴军 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第1期148-155,共8页
Thermal stability,crystallization behavior,Vickers hardness and magnetic properties of the Fe41Co7-xNixCr15Mo14C15B6Y2(x=0,1,3,5) bulk metallic glasses were investigated.The Fe41Co7-xNixCr15Mo14C15B6Y2(x=0,1,3,5) ... Thermal stability,crystallization behavior,Vickers hardness and magnetic properties of the Fe41Co7-xNixCr15Mo14C15B6Y2(x=0,1,3,5) bulk metallic glasses were investigated.The Fe41Co7-xNixCr15Mo14C15B6Y2(x=0,1,3,5) metallic glasses were fabricated by copper mold casting method.The thermal stability and crystallization behavior of the metallic glass rods were investigated by differential scanning calorimetry and isothermal experiments.Hardness measurements for samples annealed at different temperatures for different time were carried out at room temperature by the Vickers hardness tester,and magnetic measurements were performed at different temperatures by the vibrating sample magnetometer.It is shown that the addition of Ni does not play a positive role for enlarging ΔTx and GFA from parameter γ(=Tx/(Tg+Tl)),and it can,however,increase the activation energy in the initial stage of crystallization by changing the initial crystallization behavior.The minor addition of Ni can refine the crystal grain obtained from the full crystallization experiment.The primary crystallization causes the decrease of hardness in these alloys,and as the crystallization continues,the hardness in all samples increases instead due to the precipitation of carbide and boride.The annealing temperature has an obvious effect on magnetic properties of these alloys,and the minor addition of Ni can effectively prevent the alloy annealed at high temperature to transform from paramagnetic to ferromagnetic state. 展开更多
关键词 Fe-Co-Ni-Cr-C-B-Y metallic glass thermal stability annealing magnetic properties
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Structure and magnetic properties of Zn ferrite nanoparticles 被引量:2
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作者 张毅 王凯 +1 位作者 任志艳 翟亚 《Journal of Southeast University(English Edition)》 EI CAS 2009年第3期408-412,共5页
A series of ZnxFe3-xO4(x = 0, 0. 15, 0. 30, 0o 40, 0. 48, 0. 60, 0. 70 ) nanoparticles prepared by hydrothermal method are studied by use of transmission electron microscope, X-ray diffraction, vibrating sample magn... A series of ZnxFe3-xO4(x = 0, 0. 15, 0. 30, 0o 40, 0. 48, 0. 60, 0. 70 ) nanoparticles prepared by hydrothermal method are studied by use of transmission electron microscope, X-ray diffraction, vibrating sample magnetometer, superconducting quantum interference device magnetometer and Mossbauer spectrometer. All samples present a spinel structure. The lattice constant increases with the increase in the Zn content while the grain size decreases from 18 nm to 9 nm. Moreover, the saturation magnetzafion at 5 K and 293 K increases initially when x ≤ 0. 40 and subsequently decreases when x 〉 0. 40. At room temperature, Mossbauer spectra exhibit a change from a well-defined sextet spectrum to a doublet spectrum as the Zn content increases. The doublet spectrum begins to appear when x = 0. 6, while it begins when x = 0. 80 for the bulk materials. The results of magnetization and Curie temperature measurements indicate that the doublet spectrum is due to the surperparamagnetic state of the nanoparticles. Furthermore, the relationship between the hyperfine field variation and the cation distribution is discussed. The variation of magnetic properties is interpreted by the three-sublattice Yafet-Kittel (Y-K)model. 展开更多
关键词 magnetic materials Zn ferrite Mossbauer spectra magnetic properties
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Synthesis, crystal structure and magnetic properties of novel copper compound Cu(phen)(m-CBA)_2
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作者 周建良 霍艳 +4 位作者 王敏敏 王圆圆 古映莹 易小艺 张寿春 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2011年第12期2660-2664,共5页
A novel compound Cu(phen)(m-CBA)2 was synthesized with m-chlorobenzoic acid(m-CBA), 1,10-phenanthroline(phen) and Cu(OAc)2·H2O. It was characterized by IR, UV, elemental analyses and X-ray crystallograp... A novel compound Cu(phen)(m-CBA)2 was synthesized with m-chlorobenzoic acid(m-CBA), 1,10-phenanthroline(phen) and Cu(OAc)2·H2O. It was characterized by IR, UV, elemental analyses and X-ray crystallography. It crystallizes in the monoclinic crystal system with C2/c space group, a=2.9699(4) nm, b=1.15452(2) nm, c=1.5335(2) nm, β=111.118(2)°, V=4.905 1(1) nm3, Z=8, F(000)=2 328, R1=0.072 8, wR2=0.223 4 [I2σ(I)]. Structure analysis shows that the copper center coordinates with two nitrogen atoms from one 1,10-phenanthroline molecule, two oxygen atoms from two m-chlorobenzoic acid molecules, giving a distorted squared planar coordination geometry. This novel compound shows paramagnetic interactions between copper centers. 展开更多
关键词 copper (II) compound conventional synthesis crystal structure magnetic properties
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Phase evolution and magnetic properties of Nd_(9.5)Fe_(81)Zr_3B_(6.5) nanocomposite magnets
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作者 盛洪超 曾夑榕 +1 位作者 靳朝相 钱海霞 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第9期2628-2632,共5页
Melt-spun Nd9.5Fe81Zr3B6.5 ribbons were prepared by the melt-spinning technique. The phase evolution and magnetic properties were studied by X-ray diffraction, differential scanning calorimetry, transmission electron ... Melt-spun Nd9.5Fe81Zr3B6.5 ribbons were prepared by the melt-spinning technique. The phase evolution and magnetic properties were studied by X-ray diffraction, differential scanning calorimetry, transmission electron microscopy observations, and magnetization measurements. It is indicated that melt spinning at different wheel velocities caused the as-quenched ribbons to have distinctive structure. The phase transformation of the ribbons during annealing takes place in two steps: α-Fe transforms from the amorphous phase firstly, followed by formation of Nd2Fe14B phase. With increasing the initial quenching rate, the microstructure of optimally heat treated ribbons becomes coarser, which results in the weakening of the exchange coupling effect between the hard and soft phase. This leads to drastic deterioration of magnetic properties of annealed ribbons with increasing the initial quenching rate. 展开更多
关键词 ND-FE-B NANOCOMPOSITES Zr addition magnetic properties
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Thermomagnetic Properties near Transition of Compound Dy_6FeSb_2
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作者 何维 钟海长 +4 位作者 秦平力 张吉亮 曾令民 蔡格梅 秦海青 《Journal of Rare Earths》 SCIE EI CAS CSCD 2007年第S1期158-160,共3页
Thermomagnetic properties of the new compound Dy6FeSb2 were investigated by vibrating sample magnetometer. The sample of the compound Dy6FeSb2 showed soft magnetic behavior in the investigated temperature range from 8... Thermomagnetic properties of the new compound Dy6FeSb2 were investigated by vibrating sample magnetometer. The sample of the compound Dy6FeSb2 showed soft magnetic behavior in the investigated temperature range from 85 to 300 K and the ferromagnetic-paramagnetic transition of the compound was a second-order transition. The Landau theory of second-order phase transition was employed to investigate the thermodynamic transition temperature and the specific heat. The calculated transition temperature and the specific heat jump at Currie point of the compound were 143 K and 47.2 J·kg-1·K-1, respectively. 展开更多
关键词 rare-earth compound magnetic properties themomagnetic properties
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Effect of Co substitution on magnetic properties of Ni-Mn-Sn magnetic shape memory alloys 被引量:2
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作者 曹伽牧 谭昌龙 +4 位作者 田晓华 李钦赐 郭二军 王丽萍 曹一江 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2014年第4期1053-1057,共5页
The effect of Co substitution on magnetic properties of Ni-Mn-Sn shape memory alloy was revealed by first-principles calculations. Large magnetization difference in Ni-Mn-Sn alloy obtained by addition of Co arises fro... The effect of Co substitution on magnetic properties of Ni-Mn-Sn shape memory alloy was revealed by first-principles calculations. Large magnetization difference in Ni-Mn-Sn alloy obtained by addition of Co arises from enhancement of magnetization of austenite due to change of Mn-Mn interaction from anti-ferromagnetism to ferromagnetism. Total energy difference between paramagnetic and ferromagnetic austenite plays an important role in magnetic transition of Ni-Co-Mn-Sn. The altered Mn 3d states due to Co substitution give rise to difference in magnetic properties. 展开更多
关键词 ferromagnetic shape memory alloys Ni-Mn-Sn first-principles calculation magnetic properties
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Microstructure and magnetic properties of anisotropic Nd-Fe-B magnets prepared by spark plasma sintering and hot deformation 被引量:3
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作者 李小强 李力 +3 位作者 胡可 陈志成 屈盛官 杨超 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2014年第10期3142-3151,共10页
Bulk anisotropic Nd-Fe-B magnets were prepared from hydrogen-disproportionation-desorption-recombination(HDDR) powders via spark plasma sintering(SPS) and subsequent hot deformation. The influence of sintering tem... Bulk anisotropic Nd-Fe-B magnets were prepared from hydrogen-disproportionation-desorption-recombination(HDDR) powders via spark plasma sintering(SPS) and subsequent hot deformation. The influence of sintering temperature on the structure and magnetic properties of the spark plasma sintered Nd-Fe-B magnets were studied. The remanence Br, intrinsic coercivity Hcj, and the maximum energy product(BH)max, of sintered Nd-Fe-B magnets first increase and then decrease with the increase of sintering temperature, TSPS, from 650 °C to 900 °C. The optimal magnetic properties can be obtained when TSPS is 800 °C. The Nd-Fe-B magnet sinter treated at 800 °C was subjected to further hot deformation. Compared with the starting HDDR powders or the SPS treated magnets, the hot-deformed magnets present more obvious anisotropy and possess much better magnetic properties due to the good c-axis texture formed in the deformation process. The anisotropic magnet deformed at 800 °C with 50% compression ratio has a microstructure consisting of well aligned and platelet-shaped Nd2Fe14 B grains without abnormal grain growth and exhibits excellent magnetic properties parallel to the pressing axis. 展开更多
关键词 Nd-Fe-B magnet hydrogen-disproportionation-desorption-recombination(HDDR) spark plasma sintering hot deformation magnetic property
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Structural Analysis and Magnetic Properties of Gd-Doped Li-Ni Ferrites Prepared Using Rheological Phase Reaction Method 被引量:9
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作者 蒋静 李良超 徐烽 《Journal of Rare Earths》 SCIE EI CAS CSCD 2007年第1期79-83,共5页
A series of Gd-doped Li-Ni ferrites with the formula of LiNi0.5GdxFe2-xO4 where x = 0.00 - 0.08 in steps of 0.02, were prepared by thermolysis of oxalate precursors obtained by rheological phase reaction. The structur... A series of Gd-doped Li-Ni ferrites with the formula of LiNi0.5GdxFe2-xO4 where x = 0.00 - 0.08 in steps of 0.02, were prepared by thermolysis of oxalate precursors obtained by rheological phase reaction. The structure, morphology, and the magnetic properties of the samples were characterized by powder X-ray diffraction (XRD), atomic force microscopy (AFM) and a vibrating sample magnetometer (VSM). A single spinel phase was obtained in the range of x = 0.00 - 0.04. The lattice parameters of the Gd-doped samples were larger than that of pure Li-Ni ferrite, and increased in the range of 0.00 ≤ x ≤ 0.04, then decreased up to x = 0.08, because of the formation of the secondary phase (Gd- FeO3). All samples were spheric particles with an average size of about 100 nm, but agglomerated to some extent. The hysteresis loops indicated that the saturation magnetization decreased gradually with increasing Gd content, while the variation of coercivity was related to the microstructure of the Gd-doped samples. 展开更多
关键词 rheological phase Li-Ni ferrite Gd-doped structure magnetic properties rare earths
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Magnetic properties of La-Zn substituted Sr-hexaferrites by self-propagation high-temperature synthesis 被引量:6
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作者 游李顺 乔梁 +3 位作者 郑精武 蒋梅燕 姜力强 盛嘉伟 《Journal of Rare Earths》 SCIE EI CAS CSCD 2008年第1期81-84,共4页
The La-Zn substituted SrM-type ferrites with the composition of Sr1-xLaxFe12-xZnxO19 (x=0-0.4) were prepared by self-propagating high-temperature synthesis (SHS). The single SrM phase was detected by XRD in the as... The La-Zn substituted SrM-type ferrites with the composition of Sr1-xLaxFe12-xZnxO19 (x=0-0.4) were prepared by self-propagating high-temperature synthesis (SHS). The single SrM phase was detected by XRD in the as-received samples by controlling the Fe contents in the reagents. The substitution of La^3+and Zn^2+ obviously increased the magnetic properties of the as-prepared samples. The maximum improvements of Br, Hcb and (BH)m were 14.4%, 15.3% and 30.7%, respectively compared with that of the samples without La-Zn substitution. Microstructure observation by SEM showed that the SHS method benefited forming the better particle features and achieving the higher Hcj in comparison with the traditional firing method. 展开更多
关键词 high-temperature synthesis ferrites SUBSTITUTION magnetic properties rare earths
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Study on precipitation and transition mechanisms from the magnetic properties of silicon steel during annealing 被引量:6
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作者 Yong-fei Fan Hao Yu +3 位作者 Jing Sun Pan Tao Cheng-hao Song Xun Zeng 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2014年第4期379-387,共9页
Precipitates play an important role in determining the mechanical and magnetic properties of silicon steel. This paper aims to investigate the growth kinetics of precipitates in commercial silicon steel by analyzing i... Precipitates play an important role in determining the mechanical and magnetic properties of silicon steel. This paper aims to investigate the growth kinetics of precipitates in commercial silicon steel by analyzing its magnetic properties during isothermal annealing at 200℃. The growth of precipitates was studied by optical microscopy, scanning electron microscopy, transmission electron microscopy, and magnetic measurements. In combination with the coercive field and initial susceptibility, this technique offers the advantage of being non-destructive and providing quantitative information about the number, mean radius of precipitates, and fraction of transformation. An ob- served decrease in the number of precipitated particles indicates that the transformation starts from particles of appreciable initial size. 展开更多
关键词 silicon steel PRECIPITATION growth kinetics magnetic properties isothermal annealing
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