共查询到19条相似文献,搜索用时 78 毫秒
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研究了烧结NdFeB磁体的硬磁性能与晶粒取向程度的关系,结果表明:随着晶粒取向程度的增强,磁体的剩余磁极化强度Jr单调上升、内禀矫顽力jHc单调下降,磁感矫顽力BHc先上升,达到一极大值后下降,从而导致了最大磁能积(BH)max的饱和行为。应用矫顽力的发动场理论很好地解释了这一实验现象。 相似文献
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概述了近年来有关高性能Nd-Fe-B复合永磁材料矫顽力机制的研究进展,研究了工艺过程对矫顽力的影响机制和所适应的理论模型,重点探讨了双主相合金技术制备的高性能永磁材料的微结构特征与矫顽力的关系,尝试解释了双主相合金技术制备的高性能永磁材料的矫顽力机制 由传统的单合金或双合金工艺制备磁体的矫顽力机制可用发动场理论解释,且与实际相符较好.探讨了热压/热流变磁体各向异性的形成,展示了热退磁过程中烧结和热压/热流变磁体畴结构的演变规律.制备出最大磁能积约为424 kJ/m3的各向异性纳米品Nd-Fe-B磁体,研究表明,各向异性的产生主要源于再结晶过程中晶粒的择优生长和通过边界液相所促进的晶粒滑移和旋转.揭示出高性能各向异性纳米晶Nd-Fe-B磁体的典型磁畴结构是一种交换耦合畴.交换耦合畴的温度依赖关系是影响磁体使用温度的主要因素. 相似文献
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镁合金AZ31高温形变机制的织构分析 总被引:12,自引:0,他引:12
利用X射线衍射和背散射电子衍射方法测定了镁合金AZ3l高温动态再结晶和超塑形变时的宏观和微观织构,分析了晶粒内部的形变机制.结果表明,在动态再结晶和超塑形变过程中,晶粒内部的滑移机制仍起重要作用,表现为再结晶晶粒出现择优取向以及一些晶粒可充分均匀形变成长条状.宏观织构的测定表明,具有不同初始织构的两类样品高温动态再结晶时,新晶粒有不同的取向择优过程,形成相似的织构;长条形变晶粒内部开动的滑移系也有一定的差异.分析了不同温度下相同的织构对应的不同塑变机理取向成像分析表明,基面织构取向的晶粒间总伴随着较高比例的小角晶界和30°(0001)的取向关系,这是六方结构的六次对称性限制了动态再结晶时(亚)晶粒间取向差的有效增大的缘故. 相似文献
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Research Notes1. IlltroductionThe NdFeB magnetic powders produced by theHDDR (hydrogenat ion- deco mp os it ion- desorp t ionrecombination) process commonly are magneticallyisotropic. Takeshita[1] and MatzingerI2] et al. pointedout that the addition of a little Zr, Ga can inducemagnetic anisotropy for HDDR Nd(Fe,Co)B powders. In this paper, the dependence of the remanentpolarization Jr, the intrinsic coercivity jH.= and themagnetic inductive coercivity l,Hc for HDDR NdFeCoBGa bond… 相似文献
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Nd-Fe-B permanent magnets with a small amount of Cu nano-particles doping have been prepared by conventional sintered method.Effects of Cu content on magnetic properties,corrosion resistance,and oxidation properties of the magnets have been studied.It shows that the coercivity rises gradually,while the remanence decreases simultaneously with increasing Cu doping amount.Microstructure observation reveals that Cu element enriches mainly the Nd-rich phase.Autoclave test results show that the corrosion rate of the magnets decreases with increasing Cu content.After oxidation,the maximum energy product loss of the magnets with 0 and 0.2 wt% Cu nano-particles doping are 6.13% and 0.99%,respectively.Therefore,it is concluded that Cu nano-particles doping is a promising way to enhance the coercivity and corrosion resistance of sintered Nd-Fe-B magnets. 相似文献
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以废旧钕铁硼磁体为原料,采用短流程回收制备技术制备了烧结Nd-Fe-B磁体,通过添加镨钕混合稀土研究了磁体的磁性能和耐热性能.结果表明,在回收磁体中添加2% PrNd,制备的烧结Nd-Fe-B磁体的剩磁为1.31T、矫顽力为1 474.86 kA/m、磁能积为353.90 kJ/m3.与一次成品相比矫顽力恢复到102%,剩磁恢复到95%,磁能积恢复到90%.在293~393 K范围内未掺杂PrNd磁体的矫顽力温度系数为-0.589 9%/K,掺杂2%PrNd磁体的矫顽力温度系数为-0.556 4%/K,提高了磁体在高温下的耐热性能.这是由于添加混合稀土PrNd增强了主相晶粒间的去磁交换耦合作用,提高了主相的磁晶各向异性场,从而提高了磁体的矫顽力和耐热性能. 相似文献
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重点研究制备工艺对各向异性热压稀土永磁体性能的影响,探讨了热压永磁体的热变形机理和数学描述模型,并尝试从微磁结构的角度研究各向异性纳米晶Nd-Fe-B磁体,揭示纳米晶粒之间的静磁和交换耦合相互作用、磁化和反磁化、热退磁等微观机制。获得了最佳磁性能为:Hcj=1 157 kA/m,Br=1.465 T,(BH)max=426 kJ/m3纳米晶Nd-Fe-B磁体。 相似文献
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Zhongmin Chen Naxin Wang Xiaoping Song Xiaotian Wang 《IEEE transactions on magnetics》1995,31(3):2215-2219
The intergranular microstructure and coercivity of Nd richer Nd xFe93-xB7 (x=16-28) sintered magnets have been systematically studied by means of scanning electron microscopy, analytical transmission electron microscopy, scanning Auger multiprobe, thermomagnetic analysis, magnetic measurement and annealing experiments. A new stable Nd-Fe-O ferromagnetic phase with a composition NdFe2Ox (x≈0.3) and a Curie temperature of 145°C is found in the intergranular regions of the magnets, due to the introduction of a considerable amount of oxygen during magnet processing and its segregation in the intergranular regions. The phase forms at ~650°C and volume fraction reaches a maximum of ~4% in the Nd22Fe71B7 magnets. This new phase has a strong hindrance effect on the propagation of reversed domain walls between Nd2Fe14B grains, and thus leads to a considerable enhancement of coercivity. Raising the Curie temperature of this phase would be a new important approach to improve the high-temperature coercivity of Nd-Fe-B magnets 相似文献
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Y.H. Hou Y.L. Huang Z.W. Liu D.C. Zeng S.C. Ma Z.C. Zhong 《Materials Science and Engineering: B》2013,178(15):990-997
Anisotropic magnets were prepared by spark plasma sintering (SPS) followed by hot deformation (HD) using melt-spun powders as the starting material. Good magnetic properties with the remanence Jr > 1.32 T and maximum of energy product (BH)max > 303 kJ/m3 have been obtained. The microstructure evolution during HD and its influence on the magnetic properties were investigated. The fine grain zone and coarse grain zone formed in the SPS showed different deformation behaviors. The microstructure also had an important effect on the temperature coefficients of coercivity. A strong domain-wall pinning model was valid to interpret the coercivity mechanism of the HDed magnets. The increase of stray field and weakening of domain-wall pinning effects were the main reasons of the decrease of the coercivity with increasing the compression ratio. The influences of non-uniform plastic deformation on the microstructure and magnetic properties were investigated. The polarization characteristics of HDed magnets were demonstrated. It was found out that the HDed magnets had better corrosion resistance than the counterpart sintered magnet. 相似文献
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阐述了Nd2Fe14B/α-Fe纳米双相复合永磁体的磁学特性、制备方法及矫顽力机制;并结合近年来纳米复合永磁体研究的新进展,讨论了制备工艺,添加合金化元素,微结构与磁体性能的关系;最后指出了纳米复合永磁体目前存在的问题和今后的发展方向。 相似文献
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《材料科学技术学报》2020,(6)
Grain boundary diffusion process(GBDP) serves as a promising approach in improving magnetic properties and thermal stability of Nd FeB permanent magnets. Herein, non-heavy rare earth Pr-Zn films deposited on the magnet surface using DC-magnetron sputtering system are reported. The thermal stability and coercivity enhancement mechanism of Pr-Zn GBDP magnets were investigated. Results show that the coercivity of Pr-Zn GBDP magnet increases from 963.96 kA m~(-1) to 1317.14 kA m~(-1) without any remanence reduction. Notably, the demagnetization curve of Pr-Zn GBDP magnet still remains a high squareness ratio. The temperature coefficient of coercivity and anti-demagnetization ability of Pr-Zn GBDP magnet under high temperatures are improved after GBDP treatment. The well-optimized rare earth-rich(RE-rich) grain boundary phases and high effective anisotropy field of(Nd,RE)2 Fe14 B magnetic hardening layers surrounding main grains are the key factors to impact the magnetic properties and thermal stability of Nd FeB permanent magnets via GBDP treatment. 相似文献