共查询到19条相似文献,搜索用时 140 毫秒
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本文采用Biter粉纹法研究并讨论了Nd2Fe14B晶粒取向程度对磁化、反磁化过程中磁畴运动及对磁体磁性的影响。研究结果表明,磁中性状态的Nd2Fe14B晶粒的磁畴畴壁与磁体成型磁场方向的夹角α越大,则在充磁过程中越难以变成单畴,在退磁过程中越容易形成反磁化畴。磁体中α≠0°的晶粒较多时,会使磁体的M-H曲线方形度降低,剩余磁化强度、磁能积减小。 相似文献
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《功能材料》2016,(2)
纳米复合磁体的磁能积能得到大幅度提高,前提是晶粒之间存在良好的交换耦合作用,而交换耦合作用与软、硬磁相之间的界面密切相关。对Nd_2Fe_(14)B、Sm-Co、FePt基纳米复合磁体界面交换耦合和反磁化的研究展开论述。在不同的条件下,界面结构的匹配性、界面原子扩散、晶间的非晶相、界面非磁性层、界面晶格弛豫等可能有利于改善界面的结构、增强交换耦合作用,进而对反磁化过程产生影响。反磁化的不可逆过程主要发生在硬磁相内,但与软、硬磁相界面特性密切相关。不可逆反磁化在一定程度上决定了磁体的矫顽力,它可通过改善界面结构进行调控。本文旨在对纳米复合磁体界面的作用深入理解并期望能对磁体磁性能的优化提供参考。 相似文献
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利用放电等离子烧结技术(SPS)制备烧结钕铁硼磁体SPS NdFeB。为了更好地理解SPS Nd-FeB磁体的磁硬化机理,利用振动样品磁强计研究了SPS NdFeB磁体在室温下的磁化和反磁化过程。结果表明,在强度为800kA/m的较低外加磁场和强度为1760kA/m的较高外加磁场下的磁化特征明显不同,前者可称为形核控制模式,后者则为钉扎控制模式。比较样品的磁化过程和反磁化过程的曲线,发现样品的矫顽力大小等于样品磁化过程钉扎场的大小。 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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对经冷压处理的Nd-Fe-B磁粉直接进行热变形从而制得各向异性致密磁体,并研究了变形温度及变形速率对磁体密度、各向异性、磁性能及微观结构的影响.结果表明,当变形温度过低或变形速率过高时,单级热变形后磁体不易致密,且硬磁相晶粒的c轴取向度较低,因此磁体磁性能较低;而当变形温度过高或变形速率过低时,尽管磁体较为致密,磁体取向度也较高,但易出现晶粒异常长大,从而降低磁体磁性能.以适中的变形温度和变形速率热变形后,磁体具有最佳的磁性能.当变形温度为700℃及变形速率为0.1mm/s时,单级热变形磁体最大磁能积(BH)m达232kJ/m3. 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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《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
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Dongtao Zhang Ming Yue Jiuxing Zhang Lijun Pan 《IEEE transactions on magnetics》2007,43(8):3494-3496
We prepared bulk nanocrystalline SmCo6.6Nb0.4 sintered magnet material by spark plasma sintering technique. X-ray diffraction patterns show that the magnet exhibits a stable TbCu7 structure. Transmission electron microscopy indicates that the microstructure of the magnet is composed of SmCo6.6Nb0.4 single-phase grains with an average grain size of 30 nm. Magnetic measurement shows that under a 7 T magnetic field, the coercivity of the magnet reaches as high as 2.8 T; the saturation magnetization and the remanence are 69.6 and 51.4 emu/g, respectively. The magnet exhibits good thermal stability with the coercivity of 0.48 T at 773 K, and the coercivity temperature coefficient beta of -0.169%/K. 相似文献
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This paper discusses the preparation of samarium-cobalt (SmCo5) alloy powders by reduction-diffusion process. These powders were blended with equal weight percentages of soft metal/alloy
powders, such as indium, tin and solder alloy (Pb-17Sn), to prepare bonded magnets. Important magnetic properties such as
remanence, coercivity and energy product of these magnets were measured. Effect of matrix metal/alloy on the magnetic properties
of processed magnets is outlined. 相似文献
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For both sintered and nanocomposite NdFeB magnets, deltaM(H) of the Henkel plot increases from zero, and reaches a peak, then decreases and changes to the negative values with increasing applied field. This shows that the intergrain interaction changes from the exchange-coup ling type into the magnetostatic interaction type. The magnetic field corresponding to the peak of deltaM(H) is slightly smaller than the coercivity of magnet. The peak of deltaM(H) for aligned sintered magnet is greater than that for misaligned magnet. deltaM(H) peak of the nanocomposite NdFeB magnets increases with decreasing grain sizes. It indicates that the effect of alignment field on the properties of magnet is similar to that of exchange-coupling interaction. 相似文献
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研究热塑性树脂尼龙1010 作粘结剂制备高密度粘结N dFeB 永磁材料的工艺及其对粘结 永磁性能的影响。结果表明: 快淬N dFeB 磁粉的表面状态、混炼工艺及热压成型温度、压力及时间 明显影响着尼龙1010 粘结N dFeB 永磁的性能。只有经抗氧化处理的快淬N dFeB 永磁粉, 在双辊 混炼机上, 当尼龙1010 处于半熔融状态时, 在适当短的时间混合均匀后, 才可热压制成高密度的 粘结N dFeB 永磁材料。 相似文献
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Abid Hussain Tahir Abbas Amer Bashir Ziya Zubair Ahmad Hafiz Ahmad Raza 《Journal of Superconductivity and Novel Magnetism》2014,27(8):1873-1877
Pr0.75 Y 0.25Co5-based as-cast alloys were processed by high-energy ball milling to obtain nanostructured powders with high coercivity. The powders obtained after 4 h of milling exhibited nearly amorphous behavior in X-ray diffraction patterns. DSC scans of the as-milled powders indicated a process of crystallization by broad, exothermic transition peak at 503 °C. Annealing of the milled powders at 850 °C for 2.5 min in high vacuum produced fine grains of size ranging 15–30 nm with optimal microstructure and hard magnetic properties. Magnetic measurements of the annealed powders evaluated a high intrinsic coercivity, i H c of 9.3 kOe, and a remanence ratio, M r/ M max of 0.72. The magnetic hardening was attributed to higher anisotropy field of the powders and microstructural uniformity achieved by the processing methodologies. 相似文献
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采用高能球磨和放电等离子烧结技术制备了致密纳米晶Sm2Co17烧结磁体,研究了粉末和烧结磁体的结构和磁性能.球磨粉末在低温退火(<1023K)时,主相为TbCu7结构;高温退火(>1023K)时,主相为Th2Zn17结构.退火温度从923K增加到1223K,粉末的矫顽力从0.99T下降到0.12T.烧结磁体也具有TbCu7结构,磁体平均晶粒尺寸约为35nm.室温时磁体的剩磁为0.65T,矫顽力达0.87T.烧结磁体具有较好的高温性能,573K时的剩磁为0.6T,矫顽力为0.32T. 相似文献