检索结果-南通市图书馆

Effect of magnetic layer thickness on magnetic properties of Ce-Fe-B thin films

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2018年第6期36卷 619-622页

作者： Yachao Sun minggang zhu Wei Liu Rui Han Wei Li Division of Functional Material Central Iron & Steel Research Institute Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences

The Ce;Fe;B thin films with a notable out-of-plane c-axis texture were prepared by DC magnetron sputtering on a Ta buffer layer. The morphological and magnetic properties were investigated. The thickness of the magnetic layer had a dramatic effect on the formation of Ce;Fe;B phase,and excellent magnetic properties(H;≈4.25 kOe, M;/M;≈0.81) were observed for the Ce-Fe-B film with the thickness d;= 200 nm. The results of the hysteresis loops for Ce-Fe-B film（d;= 200 nm） at various measured temperatures show that a decoupling between the hard and the soft phases is observed at low temperatures, which is due to the regions with quite low anisotropy provided by the a-Fe. Moreover. it is clear that significantly various magnetization behaviors between the films with d;= 200 and 300 nm were observed with a similar trend due to the existence of the a-Fe soft phase.

关键词： Permanent magnets Ce-Fe-B film Hysteresis loops Reversible susceptibility Rare earths

Magnetic microstructure and coercivity mechanism of high performance Nd-Fe-B magnets

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2006年第Z1期25卷 630-632页

作者： zhu minggang LIU Xingmin FANG Yikun LI Zhengbang LI Wei Central Iron & Steel Research Institute Beijing 100081 China Central Iron & Steel Research Institute Beijing 100081 China Central Iron & Steel Research Institute Beijing 100081 China Central Iron & Steel Research Institute Beijing 100081 China Central Iron & Steel Research Institute Beijing 100081 China

Magnetic microstructure of high performance Nd-Fe-B magnets was investigated by using magnetic force microscopy. The correlation between magnetic microstructure and coercivity for high performance Nd-Fe-B magnets was studied. It is found that the magnets with different coercivity mechanism take on different microstructures and magnetism. Moreover, the magnetic microstructures of high performance permanent magnets can be explained by the starting field theory model.

关键词： Nd-Fe-B permanent magnets magnetic domains reversal of magnetism starting field theory

The microstructure and magnetization reversal behavior of melt-spun (Nd_(1-x)Ce_x)-Fe-B ribbons

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2018年第1期36卷 95-98页

作者： liwei song nengjun yu minggang zhu qiang wang wei li division of functional materials central iron and steel research instituteBeijing 100081China key laboratory of national education ministry for electromagnetic processing of materials northeastern universityShenyang 110819China school of materials science and engineering northeastern universityShenyang 110819China

In this study, the alloy ingots with nominal compositions of （Nd1_xCex）31FebalCoo.2Gao.1B （x = 0, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%） were prepared and then melt-spun to form nanocrystalline ribbons at the wheel speed of 20 m/s. XRD results show that all melt-spun ribbons exhibit the tetragonal structure （Nd,Ce）2Fe14B phase with the space group P42]rnmm. The Curie temperature and lattice constant decrease with the increase of Ce content. The Curie temperature decreases gradually from 306 to 247 ~C with the increase of Ce content. Those results indicate that Ce element has been incorporated into Nd2Fe14B main crystalline phase and formed （Ce,Nd）-Fe-B hard magnetic phase. It is also found that the remanence ratio （Mr/Ms） decreases from 0.693 to 0.663 and the coercivity （Hc） decreases from 18.7 to 14.2 kOe with the increase of Ce content. However, a relatively high coercivity of 18.3 kOe for （Ndl xCex）*** （x = 0.2） melt-spun ribbon is achieved. The coercivity is sensitive to microstructure. The AFM patterns show the sample （x - 0.2） has the most uniform and finest micro- structure. The magnetization reversal behavior （0M plots） is discussed in detail. The positive 0M value is observed in every sample, which confirms the existence of exchange coupling interaction. Evidently, the OM maximum value reaches 0.9 in the sample （x - 0.2）. It is indicated that the intergranular exchange coupling effect is the strongest, which is consistent with coercivity enhancing.

关键词： Ce contentMelt-spun ribbonsHigh coercivityMicrostructureRare earthsMagnetization reversal

Temperature stability and microstructure of ultra-high intrinsic coercivity Nd-Fe-B magnets

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2008年第4期27卷 358-361页

作者： HU Zhihua CHENG Xinghua zhu minggang LI Wei LIAN Fazeng Key Laboratory of the Ministry of Education of China for Anisotropy and Texture of Materials Northeastern University Shenyang 110004 China Division of Functional Materials Central Iron ＆ Steel Research Institute Beijing 100081 China Advanced Technology and Materials Co. Ltd. Beijing 100081 China

The variations of intrinsic coercivity and remanence of sintered Nd-Fe-B magnets with ultra-high intrinsic coercivity were investigated. The results showed that the intrinsic coercivity and remanence declined simultaneously with increasing temperature, but the squareness of the magnets has hardly been changed. The temperature coefficients of remanence （α） and coercivity （β） for the magnets were calculated by two different methods, and the variations of the temperature coefficients and the microstructure of sintered Nd-Fe-B magnets were analyzed. The temperature coefficients of remanence （α） and coercivity （β） for the sintered magnets are very small, and the existence of fine microstructure is necessary to obtain sintered Nd-Fe-B magnets with ultra-high intrinsic coercivity.

关键词： Nd-Fe-B magnets intrinsic coercivity sintering remanence temperature coefficient

Analysis of NdFeB multi-pole ring by SEM and MFM

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2006年第Z1期25卷 489-492页

作者： LIU Xingmin LI Xiumei FANG Yikun zhu minggang HAN Baoshan LI Wei Central Iron & Steel Research Institute Beijing 100081 China Central Iron & Steel Research Institute Beijing 100081 China Central Iron & Steel Research Institute Beijing 100081 China Central Iron & Steel Research Institute Beijing 100081 China State Key Laboratory of Magnetism Institute of Physics and Center of Condensed Matter Physics CAS Beijing 100080 China Central Iron & Steel Research Institute Beijing 100081 China

Sintered multi-pole ring that is made in America and China was analysed by SEM and MFM. The results show that the average size of American multi-pole ring is much smaller than the Chinese one and has much better orientation degree. The magnetic field of American specimen is much higher than that of the Chinese one and its average value is about 500 Gs, and more uniform distribution of the Nd-rich phase has been obtained.

关键词： ring NdFeB SEM

Coercivity enhancement of nanocrystalline hot-deformed Nd-Fe-B magnets by low-melting eutectic MM-Cu(MM=La,Ce,Pr,Nd) alloys addition

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2020年第6期38卷 594-599页

作者： Zheng Jing Zhaohui Guo Younian He Meiling Zhang Xin Wang minggang zhu Wei Li Division of Functional Materials Central Iron&Steel Research InstituteBeijing 100081China

MM85Cu15(MM = La,Ce,Pr,Nd) eutectic alloys were added into the hot-deformed Nd-Fe-B magnets to enhance the *** is found that three endothermic peaks occur on the differential scanning calorimetry curve of the MM-Cu melt-spun ribbons at 432.2,451.1 and 516.5℃.The peaks substantially correspond to three types of MM-Cu low-melting eutectic *** coercivity of magnets increases when the MM-Cu content is lower than 4 wt%,and then keeps almost no change with the content further increasing to 5 wt%.The coercivity of the hot-deformed magnets with 4 wt% and without MM-Cu addition is 948 and 683 kA/m,*** all the platelet-shaped grains are isolated by the thickened intergranular phase after MM-Cu ***,the average grain size of the magnets with MM-Cu addition decreases compared with that of the magnet without MM-Cu *** electron microscopy images show that the areal fraction of the RE-rich grain boundary phase increases from 8.6% to 15.1% after MM-Cu *** La,Ce together with Cu and Ga aggregate at the grain boundary regions separating neighboring grains and smoothing the grain ***,both the thickened grain boundary and decreased mean grain size result in the enhancement of coercivity after MM-Cu eutectic alloy addition.

关键词： Hot deformation Nd-Fe-B Coercivity MM-Cu eutectic alloy Rare earths

Superior corrosion resistance and corrosion mechanism of dual-main-phase (Ce_(15)Nd_(85))_(30)Fe_(bal)B_(1)M magnets in different solutions

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2023年第1期41卷 122-129页

作者： Yaping Wu minggang zhu Qisong Sun Lele Zhang Peng Shen Yikun Fang Wei Li Division of Functional Materials Research Central Iron and Steel Research InstituteBeijing 100081China School of Materials Science and Engineering Northeastern UniversityShenyang 110819China

The electrochemical corrosion behavior of both (Ce_(15)Nd_(85))_(30)Fe_(bal)B_(1)M sintered magnets prepared with dual-main-phase method and N45-type magnets was studied in 3.5 wt% NaCl,1.1 wt% NaH_(2)PO_(4),and 2.5 wt% NaOH solutions,*** (Ce_(15)Nd_(85))_(30)Fe_(bal)B_(1)M sintered magnets perform superior corrosion resistance than N45-type magnets in the tested *** general,two kinds of magnets exhibit the best corrosion resistance property in 2.5 wt% NaOH solution,while the worst in 3.5 wt% NaCl *** of samples before and after corrosion were *** the addition of Ce by means of dual-main-phase method,which is conducive to facilitating low-temperature sintering and grain refinement,uniform grain size and(Nd,Ce)-rich phase distribution form,give rise to narrow and thin corrosion ***,the corrosion rate of the(Nd,Ce)-rich phase is lower than that of Nd-rich *** rdingly,corro sion re sistance of (Ce_(15)Nd_(85))_(30)Fe_(bal)B_(1)M sintered magnet is superior when compared with the commercial N45-type magnet which has comparable magnetic properties.

关键词： Sintered Nd-Fe-B magnet Electrochemical corrosion behavior Dual-main-phase method Electrolyte solution Corrosion mechanism Rare earths

Abnormal corrosion behavior of dual-main phase sintered(Ce,Nd)-Fe-B magnets in different sodium solutions

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2020年第7期38卷 735-741,I0002页

作者： Xiaoning Shi minggang zhu Xiangdong Wang Shaoxiong Zhou Xin Wang Meiling Zhang Wei Li Division of Functional Material Central Iron&Steel Research InstituteBeijing 100081China Advanced Technology&Materials Co. Ltd.Beijing 100081China

Sintered(Ce,Nd)-Fe-B magnets with high cost performance were prepared by substituting of Ce for Nd with the dual-main phase *** corrosion behaviors of dual-main phase sintered(CexNd1-x)30Fe69B1(x=0.15 wt%,0.3 wt%) magnets,which were named as Ce15 and Ce30,were studied in 3.5 wt% NaCl,6.6 wt% Na2 SO4 and 3.0 wt% NaOH aqueous solutions,*** galvanic corrosion of Ce30 is stronger than that of ***,the mass loss value of Ce30 is smaller than Ce15 after free corrosion for 33 d in NaCl *** the other two solutions,all the results show that the corrosion resistance of Ce30 is better than that of *** scanning electron microscope results show that the crack and shedding of the magnetic phase of Ce30 is less than that of *** above,the abnormal corrosion behavior shows that Ce30 magnets perform better corrosion resistance than Ce15,and the degradation degree of magnetic phase mainly affects the corrosion resistance of magnets.

关键词： Corrosion Dual main phases Sintered(Ce,Nd)-Fe-B Magnetic phase Crack Rare earths

Anisotropic corrosion behavior of sintered(Ce_(0.15)Nd_(0.85))_(30)Fe_(bal)B permanent magnets

在线全文

学校读者我要写书评

暂无评论

Journal of Rare Earths 2019年第3期37卷 287-291页

作者： Xiaoning Shi minggang zhu Dong Zhou Zheng Jing Meiling Zhang Wei Li Division of Functional Material Central Iron & Steel Research Institute

In this work, the corrosion behavior of the surface parallel to the oriented c-axis(c‖) and perpendicular to c-axis(c⊥)in the(Ce_(0.15)Nd_(0.85))_(30)Fe_(bal)B dual main phase magnet was studied. With the addition of Ce,the volume fraction of RE-rich phase shown in the backscattered electron(BSE) images is basically approximate on the two surfaces. The free corrosion potential(E_(corr)) of the c‖ surface is more negative,which shows the worse corrosion resistance from the perspective of thermodynamics. While the reaction kinetics parameters with the smaller free corrosion current(i_(corr)) and the larger transfer resistance(R_(ct)) react the opposite conclusion in 3.5 wt% NaCl solution. Moreover, the c‖ surface performs smaller ions concentration of corrosion product and less damaged corrosion morphology compared to c⊥ surface after the free corrosion. The inconformity is not affected by the RE-rich phase, but by the anisotropy of the grains that the c‖ surface has larger density of the atoms and the lower ratio of(Nd, Ce)/Fe.

关键词： Sintered Nd-Fe-B Ce Dual main phase Anisotropic Electrochemistry Corrosion