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1.
李安华  赖彬  王会杰  朱明刚  李卫 《物理学报》2011,60(2):27501-027501
研究了PrxFe82-x-yTiyCo10B4C4 (x=9—10.5;y=0, 2)纳米晶薄带的结构与磁性. 结果表明,所有薄带皆主要由2∶14∶1, 2∶17和α-(Fe, Co)三相组成. 对于y=0的合金,其内禀矫顽力随Pr含量x的增加而增加,剩磁随Pr含量x的增加而减小. 以Ti置换部分Fe (y=2),合金的磁性能得到显著提高,表现为:添加Ti后,合金的剩磁Br基本不降低,x=10.5时合金的Br值甚至有较明显的提高;同时添加Ti后,合金的内禀矫顽力及退磁曲线的方形度都明显改善. 当x=10.5,y=2时,合金薄带的磁性能达到最佳值为: Br=9.6 kGs(1 Gs=10-4 T),iHc =10.2 kOe(1 Oe=79.5775 A/m)和(BH)max=17.4 MGOe. 随着Pr含量的提高,合金中的硬磁相2 ∶14 ∶1的含量相对增加,内禀矫顽力提高;而Ti置换Fe抑制了软磁相α-(Fe, Co)在快淬和热处理过程中的优先长大,使合金中软磁相和硬磁相的晶粒尺寸及比例趋向最佳组合,交换耦合作用明显增强. 关键词: 纳米晶永磁材料 2Fe14(C')" href="#">Pr2Fe14(C B) Ti添加 交换耦合  相似文献   

2.
本文采用速凝甩带-氢破-气流磨-取向成型-烧结回火等工序,同时添加Dy和Co元素,制备了烧结Nd25.5Dy6.5Co13FebalM1.05B0.98磁体(Co13磁体),室温下磁能积(BH)max=30.88 MGOe,矫顽力Hcj=19.01 kOe.与Nd30Dy1.5Co0.5FebalM1.05B0.98(35SH)磁体相比, Co13磁体的室温磁性能略低,但温度稳定性显著提升,剩磁温度系数α从–0.136%/℃提升至–0.065%/℃(室温—180℃);居里温度TC从310℃升高至约454℃;最高使用温度TW从165℃提升到约200℃.力学性能测试和断口分析表明, Co13磁体中由于Co含量较高,主相晶粒发生解理断裂的比例提高...  相似文献   

3.
丁勇  陈仁杰  郭帅  刘兴民  李东  闫阿儒 《物理学报》2011,60(5):57103-057103
本文讨论了不同含量的Dy元素对速凝条带微观组织的影响,得出Dy的添加量为1%—2%(at%)时条带的微观结构得到最优化,柱状晶生长均匀一致,具有良好的沿c轴取向度.同时,急冷面的细小等轴晶生长区域减少,氢破后相应的磁粉抗氧化性能增强. 关键词: 速凝片 织构 微观组织 氢破  相似文献   

4.
杨应昌  徐立刚  李学东 《物理学报》1986,35(8):995-1001
本文研究了Al在R2(Fe1-xAlx)14B多元合金中的固溶度(R=Nd和Y),当x<0.1时,可形成四方结构。研究了在此类合金中,饱和磁化强度、居里温度、磁晶各向异性等内禀磁性,以及矫顽力和磁能积等永磁性能随Al含量的变化。发现以Al代换Fe时,使铁次点阵的磁晶各向异性出现极值;同时以Al代换Fe时,可使磁体的矫顽力显著提高。以Co和Al同时对Fe进行代换,制造成分约为Nd16.5B 关键词:  相似文献   

5.
胡伯平  张寿恭 《物理学报》1987,36(9):1177-1181
本文对R13Fe74Si13(R=Ce,Pr,Nd,Gd,Tb,Dy,Ho,Er,Y)三元合金的结构和磁性进行了研究。结果表明,R13Fe74Si13的主相为R2(Fe0.85Si0.1517赝二元金属间化合物,而不出现类似于R2Fe14B的三元 关键词:  相似文献   

6.
董生智  李岫梅  李卫 《物理学报》1999,48(13):62-67
利用快淬法制备了Nd4.5Fe76.3Ga0.3Co1.0B18非晶合金,晶化处理后获得主相为Fe3B与Nd2Fe14B的纳米晶永磁材料.采用X射线衍射、透射电子显微镜及磁测量手段分析研究了材料的微观结构与磁性能,并通过测量磁体的δM曲线,研究了晶粒间的交换耦合作用及其与微观结构、磁性能的关系. 关键词:  相似文献   

7.
万虹  戴道生  方瑞宜  刘尊孝  兰健 《物理学报》1989,38(10):1551-1558
本文通过对非晶态轻稀土Pr,Nd和过渡族金属Fe,Co,Ni薄膜合金的低温磁性研究,分别得到了(Pr,Nd)x-(Fe,Co,Ni)1-x合金中Pr,Nd和Fe,Co,Ni金属磁矩随成份x的变化,并且通过对磁矩的研究得到Pr离子的4f电子可能有退局域化的结论。 关键词:  相似文献   

8.
Ga替代对纳米晶Nd(Fe,Co)B黏结磁体磁性能的影响   总被引:3,自引:0,他引:3       下载免费PDF全文
朱明刚  李卫  董生智  李岫梅 《物理学报》2001,50(8):1600-1604
探讨了微量的Ga替代Fe对Nd2(Fe,Co)14B/(Fe,Co)3B+(少量)α-Fe永磁材料的晶体结构及磁性能的影响,并讨论了双相纳米晶磁体性能的变化机理以及所适用的理论模型.结果表明,Ga的添加不仅使晶粒尺寸显著变小,而且在Ga含量x<1at%的范围,随着x的增加,Br和(BH)max随退火时间的变化关系由形似马鞍的曲线转化为抛物曲线;矫顽力jHc先下降到一个最小值后再上升;当x=0.2时,综合磁性能较好 关键词: 双相纳米晶磁体 快淬 退火 交换耦合 磁性能  相似文献   

9.
1983年,Sagawa等人定理布,他们用一般粉末冶金工艺研制成功具有优良磁性的Nd-Fe-B 永磁体。这一发现展示了第三代稀土永磁材料 研究和生产的美好前景,开辟了稀土-过渡金属-类金属三元或多元合金磁性研究的广阔领域.近几年来,国内外永磁领域广泛开展了对R2Fe14B系列及其相应取代化合物(Nd.Pr,Dy,Er)2(Fe。Co,Mn,M)14(B,Si。X)的结构及磁栓方面的研究工作(M,X为其他元素). 本刊于1985年第10期刊登了何文望先生的文章[1],对第三代稀土永磁材料及其进展作了详细的论述.本文将简要介绍Nd-Fe-B永磁体的一般特性,较详细地讨论R2Fe14B化…  相似文献   

10.
冯维存  高汝伟  李卫  韩广兵  孙艳 《中国物理》2005,14(8):1649-1652
本文采用统计平均方法研究了软、硬磁性晶粒尺寸及相分布对Nd2Fe14B/α-Fe纳米复合永磁材料矫顽力的影响。计算结果表明:对于单相纳米硬磁材料,磁体矫顽力随着硬磁性晶粒尺寸的减小而降低;对于软、硬两磁性相组成的Nd2Fe14B/a-Fe纳米复合永磁材料,两相的随机分布将导致磁体矫顽力随硬磁性晶粒尺寸的减小呈现极大值。本文的计算结果还表明当硬磁性晶粒尺寸大于软磁性晶粒的最佳尺寸时(15nm),具有多层膜结构的Nd2Fe14B/a-Fe纳米复合永磁材料将比两相随机分布时具有更大的矫顽力。  相似文献   

11.
Magnetization measurements on the heavy rare earth molybdenum sulfides, (RE)1.2Mo6S8 (RE = Gd, Tb, Dy and Ho) were performed to further clarify the natures of their magnetic orders found in our recent resistivity and ac susceptibility measurements below 1 K. The variations of their magnetic and superconducting transition temperatures along the series of the rare earth ions in the Periodic Table are interpreted by means of available theories.  相似文献   

12.
The formation of the 1/1 crystal approximant phase (1/1 phase) to the icosahedral phase (i phase) in In-Pd-RE (RE: rare earth metal) systems has been investigated. A new series of 1/1 phases were found in In53Pd33RE14 (RE; Y, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, and Tm) alloys. For Y, Sm, Gd, Tb, Dy, and Ho, the 1/1 phases were found in annealed alloys, indicating that they are thermodynamically stable. The atomic structure of the 1/1 phases was directly observed by high-angle annular dark-field imaging performed via scanning transmission electron microscopy, revealing that the 1/1 phases consisted of a periodic arrangement of Tsai-type icosahedral clusters. Further, the atomic size effect on i phase formation, as well as formation conditions previously reported for other Tsai-type i and 1/1 phases were examined. It was found that the ratio of the atomic radius of base metals such as In and Pd affects i phase formation. Moreover, the appropriate range of the radius ratio for i phase formation was narrower than that for 1/1 phase formation.  相似文献   

13.
Two 2D rare earth terbium and dysprosium coordination polymers with 2,4-pyridinedicarboxylate and oxalate anions have been synthesized by hydrothermal method, the formula is {[RE(pda)(ox)0.5(H2O)4]·2H2O}n (RE = Tb (1) and Dy (2); H2pda = 2,4-pyridinedicarboxylic acid; ox = oxalate anion). The two complexes are isomorphic and crystallized in monoclinic system, P21/c space group. Each pda anion connects two rare earth ions with 2- carboxyl group and the nitrogen atom but the 4- carboxyl group does not coordinate with rare earth ions. Each ox anion connects two rare earth ions by μ 2-bridge way. Both the complexes exhibit intense characteristic luminescence of Tb(III) or Dy(III) ion with excitation of UV-rays.  相似文献   

14.
We present a review of inelastic neutron scattering results on very diluted rare earth (RE)-Laves phases. A systematic investigation to study crystal electric fields, experienced by single rare earth ions in a metallic environment, was done on (RE,R)Al2, with RE=Pr, Nd, Tb, Dy, Ho, Er, Tm andR=Sc, Y, La. We show the influence of the 4f-ions on the crystal fields as well as the influence of the host lattices. The rare earth atoms in ScAl2 have been studied for the first time and most of the other alloys, with LaAl2 and YAl2 as hosts, have been studied for the first time with magnetic atom concentrations below 1 at% and/or with good resolution for low energy excitations. Furthermore we studied the dynamics of 4f-moments, which are coupled to the conduction electrons by determining the coupling constants. We present a comprehensive set of crystal field parameters and coupling constants from these systematic studies and discuss them qualitatively within the available theoretical models. The influence of magnetic atom concentration on crystal field spectra will be shown in part II.  相似文献   

15.
The effect of thermal treatment on the magnetic properties and structure of magnets made from an alloy of (wt %) 6.3 Nd, 6.84 Pr, 14.5 Dy, 2.12 Tb, 2.25 Gd, 14.0 co, 52.62 Fe, 0.08 Al, 0.03 Cu, 0.03 Re, 1.23 B is investigated. Following the optimum heat treatment (1175 K, 7.2 ks + cooling V = 0.02 K/s+ 675 K, 3.6 ks), baked magnets have the following magnetic properties at 300 K: B r = 9.93 T, j H c = 1640 kA/m, H k = 1360 kA/m, BH max = 168 kJ/m3, α < |0.01|% K in the temperature range of 223–373 K. Nanoheterogenic areas 8–12 nm in size are found in grains of R 2(Fe,M)14B-type magnetosolid phase by means of atomic force microscopy.  相似文献   

16.
Magnetic powders for sintered NdFeB magnets have been prepared by using an advanced processing method including strip casting, hydrogen decrepitation, jet milling and rubber isotropic press. The effects of Dy, Ga and Co addition on the microstructure and magnetic properties of sintered magnets have been investigated. By adopting a suitable component ratio and adjusting proper technological parameters, we have prepared high-coercivity sintered NdFeB magnets with hard magnetic properties of jHc=25.6 kOe, Br=13.2 kG and (BH)max=39.9 MGOe. The temperature coefficient of coercivity of the magnets (between 20 and 150 °C) is –0.53%/°C. The magnetic properties at high temperature satisfy the needs of permanent magnet motors.  相似文献   

17.
Nanocrystalline (Nd,Dy)16(Fe,Co)76−xTixB8 magnets were prepared by mechanical alloying and respective heat treatment at 973–1073 K/30–60 min. An addition of 0.5 at % of Ti results in an increase of coercivity from 796 to 1115 kA m−1. Partial substitution of Nd by Dy results in an additional increase of coercivity up to 1234 kA m−1. Mössbauer investigations shows that for x?1 the (Nd,Dy)16(Fe,Co)76−xTixB8 powders are single phase. For higher Ti contents (x>1) the mechanically alloyed powders heat treated at 973 K are no more single phase, and the coercivity decreases due to the presence of an amorphous phase. A heat treatment at a higher temperature (1073 K) for longer time (1 h) results in the full recrystallisation of powders. The mean hyperfine field of the Nd2Fe14B phase decreases for titanium contents of 0?x?1, and remains constant for x>1. This indicates that the Ti content in the Nd2Fe14B phase reaches its maximum value.  相似文献   

18.
Two novel ternary rare earth complexes of Tb(III) and Dy(III) perchlorates with bis(benzoylmethyl) sulfoxide (L) and benzoic acid (L′) had been synthesized and characterized by elemental analysis, coordination titration analysis, molar conductivity, IR, TG-DSC, 1HNMR and UV spectra. The results indicated that the composition of these complexes was REL5L′(ClO4)2·nH2O (RE= Tb(III), Dy(III); L=C6H5COCH2SOCH2COC6H5, L′=C6H5COO; n = 6,8). The fluorescence spectra illustrated that the ternary rare earth complexes presented stronger fluorescence intensities, longer lifetimes and higher fluorescence quantum efficiencies than the binary rare earth complexes REL5·(ClO4)3·2H2O. After the introduction of the second ligand benzoic acid group, the relative fluorescence emission intensities and fluorescence lifetimes of the ternary complexes REL5L′(ClO4)2·nH2O (RE= Tb(III), Dy(III)) enhanced more obviously than the binary complexes. This indicated that the presence of both organic ligands bis(benzoylmethyl) sulfoxide and the second ligand benzoic acid could sensitize fluorescence intensities of rare earth ions, and the introduction of benzoic acid group was resulted in the enhancement of the fluorescence properties of the ternary rare earth complexes. The phosphorescence spectra were also discussed.  相似文献   

19.
张然  刘颖  高升吉  谢治  涂铭旌 《物理学报》2008,57(1):526-530
在之前研究Nb元素的添加对快淬(Nd,Dy)11.5Fe82.4-mNbmB6.1永磁体磁性能、温度特性及显微组织影响的基础上,进一步研究了Dy元素在Nd11.5-nDynFe81.4Nb1B6.1 (n=0,0.5,1,1.5,2)永磁体中 关键词: NdFeB 磁性能 温度特性 显微组织 X-ray absorption fine structure  相似文献   

20.
A systematic study of the formation, structure and magnetic properties of (Nd,Dy)3Fe27.5(Ti,Mo)1.5 compounds has been performed. Rietveld analyses of the X-ray patterns of the samples indicate that the concentrations of Ti and Mo affect the formation and structural properties slightly, whereas different rare-earth (Nd and Dy) contents influence them significantly. It is found that high Dy contents make it difficult to form the 3:29-type structures. The Curie temperatures of Nd2.1Dy0.9Fe27.5Ti1.5−xMox decrease monotonically as more Ti was replaced by Mo but their saturation magnetizations remain almost unchanged; in contrast, for Nd3−yDyyFe27.5TiMo0.5, their saturation magnetizations decrease monotonically with increasing Dy contents while their Curie temperatures are constant.  相似文献   

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