Nd8-xDyxFe82Co6B4纳米复合永磁材料的磁性能

针对NdFeB纳米复合永磁材料的矫顽力偏低的现状,采用熔体快淬法制备了Nd8DyxFe82Co6B4（x=0,0．4,0．8,1．2,1．6）纳米复合永磁材料,研究了Dy和Co的添加对NdFeB纳米复合永磁材料的磁性能的影响．研究结果表明,Dy的添加可提高材料的各向异性场,提高矫顽力,但是Dy元素的添加使材料的剩磁降低,结晶温度升高,因此添加量不宜过多;复合添加Co原子不仅可以提高材料的剩磁和矫顽力,而且可以弥补只添加Dy元素使材料的结晶温度升高的缺陷．在最佳的热处理条件下,Dy含量x=0．8时的样品表现出最佳的磁性能,矫顽力jHc=524kA／m,剩磁Br=1．11T,最大磁能积（BH）max=158kJ／m^3．     

熔体过热度对Fe_(78)Si_9B_(13)非晶条带磁性能的影响

为了研究合金熔体过热度和退火温度对Fe_(78)Si_9B_(13)非晶条带磁性能的影响,在180、200和230℃3个不同合金熔体过热度下利用单辊法制备了宽142 mm、厚23μm的非晶条带.在350~370℃范围内选取5个退火温度对非晶条带进行纵向磁场退火,并利用硅钢测试仪对退火后的非晶条带进行磁性能测试.结果表明,随着合金熔体过热度的增大,非晶条带的激磁功率和损耗均呈下降趋势.随着过热度和退火温度的降低,非晶条带的磁性能分布区间变窄,但其稳定性增强.适当提高过热度和热处理温度有助于获得具有最佳磁性能的非晶条带.     

Fe_xPt_(100-x)薄膜的磁性能研究

用直流磁控溅射方法和原位退火工艺在玻璃基片上制备了FexPt100-x纳米膜.研究发现Fe含量对FePt纳米膜的磁特性有很大的影响.矫顽力和△H随Fe含量的增加而增大.当x=48时,矫顽力Hc达到了1040 kA/m,样品出现很好的有序化L10织构;△H取得最大值,颗粒间相互作用最小.FexPt1-x薄膜的矩形比S随着x的增加而增大,x>46时S值接近1,在一定程度上表明了此时读出信号强度较大;开关场分布SFD的变化情况刚好与此相反,Fe48Pt52获得的SFD值近似等于0.8,说明转变位置波动弱,来自转变的信号噪音低.     

Fe3B添加量对Nd-Fe-B快淬薄带结构与磁性能的影响

通过在Nd2Fe14B合金中按Fe3B原子比同时添加Fe与B,研究了Nd15Fe77B8、Nd9Fe81B10、Nd4.5Fe77.0B18.5 3种合金薄带的结构与磁性能.试验发现,40 m/s的快淬速度使三种合金薄带中形成了较多的非晶相,而且随着合金中Fe3B添加量的增加,薄带的非晶形成能力增强、α-Fe与Fe23B6含量增加、Nd2Fe14B含量减少,磁性能单调降低.经680℃保温10 min退火处理后,3种薄带中的非晶相明显减少,Fe3B相消失,.α-Fe与Fe23B6含量随Fe3B添加量的增加而增加.其中,薄带中Nd2Fe14B晶粒约50 ～ 100 nm,而α-Fe晶粒一般小于50 nm.Nd15Fe77B8退火薄带更多地表现为单硬磁相特征;Nd9Fe81B10退火薄带中形成了α-Fe/Nd2Fe14B/Fe23B6三相交换耦合微结构,剩磁比达到了0.612,并获得最大的剩磁58.3 A· m2/kg;而Nd4.5Fe77.0B18.5薄带中Fe23B6与α-Fe含量太高,矫顽力太低而使剩磁增强效应不明显.     

快淬纳米复合Nd9Fe80Co4Nb1B6永磁合金相结构与磁性能研究

利用X线衍射仪、振动样品磁强计等测试手段研究了纳米复合Nd9Fe80Co4Nb1B6合金的相结构与磁性能,结果表明:淬速为20 m/s的合金,经710℃退火处理后,合金软硬磁性相的晶粒尺寸细小,两相之间具有较强的交换耦合作用,合金具有优良的综合磁性能,即剩磁为0.95 T,矫顽力达到540 kA/m,最大磁能积为112 kJ/m3.选择适当的快淬速度有利于改善退火后合金的相结构,提高合金的综合磁性能.     

Enhancement of magnetic properties and thermal stability of nanocrystalline （NdDyTb）12.3（FeZrNbCu）81.7B6.0 alloy with Co substitution

The major drawbacks of Nd-Fe-B magnets are relatively low Curie temperature and poor thermal stability. Ribbons with the near stoichiometric 2:14:1 composition of Nd_(10.8)Dy_(0.75)Tb_(0.75)Fe_(79.7-x)Co_xZr_(0.8)Nb_(0.8)Cu_(0.4)B_(6.0)(x=0, 3, 6, 9, 12, 15) were prepared by rapid quenching and subsequent heat treatment. The effect of Co element on the magnetic properties, thermal stability, and microstructure of the ribbons was systematically studied by vibrating sample magnetometer(VSM), thermal magnetic analysis, atomic force microscopy (AFM), and transmission electron microscopy (TEM).It was found that Co substitution was significantly effective in improving the magnetic properties and the thermal stability of nanocrystalline ribbons. Although the intrinsic coercivity decreased from 1308.7 kA/m for x=0 to 817.4 kA/m for x=15, the remanence polarization and maximum energy product increased from 0.839 T and 116.5 kJ/m~3 for the Co-free samples to 1.041 T and 155.1 kJ/m~3 for the 12at% Co-substituted samples,respectively.About 10 K increase in Curie temperature was observed for the 2:14:1 phase with lat% Co substitution. The absolute values of temperature coefficients of induction and coercivity were significantly decreased with Co substitution, which may be attractive for high operational temperature applications. The microstructure of nanocrystalline ribbons was slightly refined with Co substitution.     

Fe-Si-B-Nb-Cu-Zr非晶（纳米晶）合金的磁性机理研究

采用单辊甩带法制取了Fe-Si-B-Nb-Cu-Zr非晶合金薄带。利用X射线衍射仪（XRD）、差示扫描量热法（DSC）和振动样品磁强计（VSM）等手段对非晶态和晶化后的薄带的微观结构和磁性能进行了表征和测试,研究了Fe-Si-B-Nb-Cu-Zr合金中磁性能随着Zr含量以及退火温度变化的磁性机理。结果表明,在铸态Fe-Si-B-Nb-Cu-Zr非晶合金中,饱和磁感应强度Bs随Zr含量的增加而减小,矫顽力Hc随Zr含量的增加而增大。经过退火处理后的Fe-Si-B-Nb-Cu-Zr合金的饱和磁感应强度变化不大,但矫顽力随着退火温度的升高先减小后增高,矫顽力在510℃退火时达到最小值,但随着温度增加矫顽力进一步增大。在510℃退火时纳米晶粒与非晶相之间的体积比达到最佳,有效各向异性〈K〉最小,软磁性能最好。     

添加Mo元素对Fe40Co40Zr9B10Ge1合金晶化过程和磁性能影响

采用单辊快淬法制备Fe40Co40Zr9B10Ge1和Fe40Co40Zr5Mo4B10Ge1两种非晶合金,并在不同温度下对其进行热处理。利用XRD和VSM两种仪器对合金的微观结构和磁性能进行测试分析,研究Mo添加对Fe40Co40Zr9B10Ge1合金晶化过程和磁性能的影响。结果表明,两种合金在晶化初期均有α-Fe(Co)相从非晶基体析出,但高温热处理后的晶化产物不同,Mo添加减少了高温金属化合物的含量。低于675℃热处理,Mo添加降低了合金晶化过程中析出α-Fe(Co)相的晶粒尺寸和合金的矫顽力。     

Crystallization behavior of Fe_(78)Si_(13)B_9 metallic glass under high magnetic field

The effects of high magnetic field on the crystallization behavior of the Fe78Si13B9 metallic glass ribbon were studied. The samples were isothermal annealed for 30 min under high magnetic field and no field,respectively. Microstructure transformation during crystallization was identified by X-ray diffraction and transmission electron microscopy. It was found that the crystallizations of Fe78Si13B9 metallic glass processed under different conditions were that the precipitation of dendrite α-Fe(Si) and spher...     

Effect of annealing time on the exchange coupling interactions and microstructure of nanocomposite Pr7.5Dy1Fe71Co15Nb1Ba4.5 ribbons

The influence of annealing time on the magnetic properties and microstructure of nanocomposite Pr7.5Dy1Fe71Co15Nb1B4.5 ribbons was systematically investigated by the methods of vibrating sample magnetometer (VSM), X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). Interaction domains derived from strong exchange coupling interactions between hard and soft magnetic grains were imaged using magnetic force microscopy (MFM). Maximum remanence, intrinsic coercivity, and maximum energy product values were obtained in the ribbons annealed at 700℃ for 15 min, which were composed of Pr2(Fe, Co)14B, α-(Fe, Co), and slight Pr2(Fe, Co)17 phases. Although Jr, Hci, and (BH)max decreased gradually with further increase of annealing time, it is emphasized that comparatively high Jr and Hci and (BH)max were obtained in a wide annealing time period of 15 to 360 min. The shape of initial magnetization curves and hysteresis loops change as a function of annealing time, indicating different magnetization reversal routes, which can be fully explained by the corresponding microstructure.     

Effect of vacuum annealing on the characteristics of composite pellets containing DBSA-doped polyaniline and Fe nanoparticles

The DBSA-PANI-Fe composite powder with 50wt% of Fe nanoparticles was prepared by mechanically mixing the DBSA-doped polyaniline powder and Fe nanoparticles. The composite powder was compacted to pellets and the pellets were an-nealed in vacuum at 443, 493,543, and 593 K for 60 and 120 min. The conductivity of the pellet increases markedly with increasing the annealing temperature up to 493 K, and then decreases with further increasing the annealing temperature. When the pellet was annealed at 493 K for 60 rain, the increment of conductivity reaches a maximum value, and the conductivity is 2.6 times as large as that of the pellet unannealed. The conductivities of the pellets annealed under the conditions of 543 K/120 min, 593 K/60 min, and 593 K/120 rain are lower than the conductivity of the pellet unannealed. For all the pellets, the variation in conductivity with tem-perature reveals that the charge transport mechanism can be considered to be 1-D variable-range-hopping (1-D VRH). The composite pellet shows a magnetic hysteresis loop independent of the annealing condition. The saturation magnetization is about 5.4x104emu/kg. The saturation field and the coercivity are estimated to be 4.38x 105 and 3.06x104 A/m, respectively. The crystalline struc-ture of Fe nanoparticles in the composites does not change with the annealing condition. The annealing condition cannot destroy the polymer backbones.     

Effect of Dy on Structure and Magnetic Properties of Dy_xFe_(60.5-x)Pt_(39.5) Alloys

Effects of the content of Dy on structure and magnetic properties of DyxFe60.5-xPt39.5 alloys(x = 0, 0.5, 1.0, 1.5) were investigated. The results of XRD analysis proved that the phase-transitional temperature of DyxFe60.5-xPt39.5 alloys from disordered face-centered-cubic structure to ordered face-centered-tetragonal cubic structure decreases with the increase of the content of Dy(x). Suitable content of Dy can improve the exchange coupling between soft magnetic phase and hard magnetic phase by refining gr...     

Microstructure and properties of low-temperature aged Dy-doped Nd-Fe-B magnet

In this work, a low temperature ageing process for the high coercivity Dy-doped Nd-Fe-B magnets was developed by the optimizing ageing process. The experimental results show that there is no difference in microstructures, crystal orientation, magnetic and mechanical properties between the low-temperature aged and the two-stage aged sintered Dy-doped Nd-Fe-B magnets. Because of the uneven stress distribution in the sintered Dy-doped Nd-Fe-B magnet and the high activation of Dy element, Dy atoms could diffuse into the main crystal phase and the grain boundary phases of the magnets during low-temperature ageing process, which results in the reasonable distribution of Dy element and formation of the thin and uniform grain boundary phases, which are the main reasons to improve intrinsic coercivity of the Dy-doped Nd-Fe-B magnets by the low-temperature ageing.     

退火处理对Ti-Zr-Cu-Be块体非晶合金力学性能的影响

采用铜模铸造法制备了直径为2mm的Ti55-xZr10+xBe27.5Cu7.5(x=0,10,20)块体非晶合金,并对其进行等温退火处理.利用X射线衍射(XRD)、扫描电镜(SEM)、差氏扫描量热仪(DSC)及压缩试验等方法研究了非晶合金的相结构、显微组织和热稳定性,以及退火处理对其力学性能的影响.结果表明:该系列合金在553 K及583 K下保温长达5 h时间内依然表现为非晶态.退火处理后,Ti35Zr30Be27.5Cu7.5合金屈服强度、断裂强度均提到了提高,其中在583 K下保温1 h后屈服强度、断裂强度分别达到了1 921、2 169 MPa;其塑性由处理前的3.47%提高到了6.57%.Ti45Zr20Be27.5Cu7.5合金在退火后其力学性能变化不明显.Ti55Zr10Be27.5Cu7.5合金随着退火温度及保温时间的增加其屈服强度、断裂强度及塑性均明显降低.     

高矫顽力烧结钕铁硼永磁研究进展

烧结钕铁硼稀土永磁具有超高的磁性能,但是居里温度较低,使其在高温领域的应用受到一定的限制.新能源汽车、风力发电等新兴产业的快速发展,大幅拉升了对耐高温烧结钕铁硼的市场需求.因此,为了提高钕铁硼材料的使用温度,通过开发新技术来提高烧结钕铁硼矫顽力;同时,为了降低产品成本和对重稀土金属的消耗,开发低Dy或无Dy的高矫顽力烧结钕铁硼磁体成为目前的研究热点.研究发现,采用细化晶粒技术、晶界扩散技术以及晶界掺杂技术均能不同程度地提高钕铁硼磁体的矫顽力.综述了这3种新技术的最新研究进展.     

Fe-Zr-M-B(M=Cr,Nb,W)合金系列的热稳定性、微观结构和磁性能研究

采用单辊快淬法制备Fe_91-xZr₇Cr₂B_x(x=10,12)和Fe₈₁Zr₇M₂B₁₀(M=Nb,W)非晶合金,并对上述非晶合金进行不同温度热处理。合金的热性能、微观结构及磁性能分别利用X射线衍射仪（XRD）、同步差热分析仪(STA) 和振动样品磁强计(VSM）测得。研究表明四种非晶合金的STA中均存在三个晶化放热峰,但初始晶化产物及晶化过程不同,Fe₈₁Zr₇Nb₂B₁₀非晶合金的初始晶化产物与Fe₈₁Zr₇Cr₂B₁₀合金相似为单一α-Fe相,Fe₈₁Zr₇W₂B₁₀非晶合金的初始晶化产物与Fe₇₉Zr₇Cr₂B₁₂合金相似为α-Fe相和Fe₂₃B₆相。不同的晶化产物导致合金的矫顽力(Hc)随热处理温度的变化存在差异,Fe₈₁Zr₇Nb₂B₁₀合金经热处理后具有较低的矫顽力(Hc)。     

Dy纳米粉含量对烧结Nd-Fe-B磁体的影响

为了改善烧结Nd-Fe-B磁体的磁性能和力学性能,采用二元合金法添加Dy纳米粉制备了高性能Nd-Fe-B磁体.利用扫描电子显微镜、X射线衍射仪、粒度分布仪、磁滞回线测试仪与维氏硬度仪对烧结Nd-Fe-B磁体的形貌、微观结构、化学成分、磁性能和力学性能进行了分析.结果表明,随着Dy元素质量分数的增加,磁体矫顽力大幅提高,剩磁和最大磁能积略有下降.相比未添加Dy元素的磁体,当Dy元素质量分数为0.8%时,磁体矫顽力提高了5.4%,剩磁和最大磁能积分别下降了1.3%和1.5%,维氏硬度提高了7.1%,此时磁体的综合磁性能最优.     

Ga 对 Fe40Ni40P14B6 非晶合金电化学腐蚀行为的影响

具有高的玻璃形成能力Fe基非晶合金(Fe40Ni40P14B6)100-xGax(x=0,2.5和4.5)是利用单辊铜轮旋转的方法制备出来的.用电化学的方法研究非晶合金(Fe40Ni40P14B6)100-xGax(x=0,2.5和4.5)分别在1 mol/L和3 mol/L的HCl溶液中腐蚀行为,结果表明:非晶合金(Fe40Ni40P14B6)100-xGax(x=0,2.5和4.5)在HCl溶液中具有较高的腐蚀特性,并且随着Ga含量的增加,铁基非晶合金的耐腐蚀性能增加.另外,非晶合金(Fe40Ni40P14B6)100-xGax(x=0,2.5和4.5)与不锈钢(1Cr18Ni9Ti)分别在1 mol/L和3 mol/L的HCl溶液中的腐蚀行为相比,非晶合金的耐腐蚀性能更好.     

镁锌铁氧体粉末的水热法合成及其矫顽力机理

采用水热法合成名义成分为Mg1-xZnxFe2O4(x=0,0.2,0.4,0.6和0.8)的铁氧体粉末样品,采用X射线衍射仪、扫描电镜和振动样品磁强计等对其结构和矫顽力机理进行研究。结果表明:Zn含量增加有利于(Mg,Zn)Fe2O4铁氧体的成相,晶格常数也随着x的增加而增加;与x=0的样品相比,普通软磁材料矫顽力较大,其他样品的矫顽力呈现典型的软磁铁氧体值,且随着x的增大矫顽力呈逐渐减小的趋势,这与晶粒大小有密切关系;样品中微米级的大颗粒是纳米级小晶粒的聚集体。     

Effect of Dy on structure and magnetic properties of DyxFe60.5?xPt39.5 Alloys

Effects of the content of Dy on structure and magnetic properties of Dy _x Fe_60.5−x Pt_39.5 alloys(x=0, 0.5, 1.0, 1.5) were investigated. The results of XRD analysis proved that the phase-transitional temperature of Dy _x Fe_60.5−x Pt_39.5 alloys from disordered face-centered-cubic structure to ordered face-centered-tetragonal cubic structure decreases with the increase of the content of Dy(x). Suitable content of Dy can improve the exchange coupling between soft magnetic phase and hard magnetic phase by refining grain size, while the remanence ratio and coercivity of the Fe_60.5Pt_39.5 alloy can be significantly improved by a small replacement of Fe by Dy, good magnetic properties were obtained in Dy_0.5Fe_60.0Pt_39.5 alloys.