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Structural, Magnetic, and Electrical Properties of RE Doped Sr<sub>0.82</sub>RE<sub>0.18</sub>Fe<sub>12-x</sub>Al<sub>x</sub>O<sub>19</sub>(RE = Gd, Pr, Sm) Compound 预览
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作者 Dom Lal Kunwar Dipesh Neupane +1 位作者 Jiba Nath Dahal Sanjay R. Mishra 《材料物理与化学进展(英文)》 2019年第9期175-198,共24页
Among the family of ferrites, M-type hexaferrites has many industrial applications ranging from simple magnets to microwave devices. Improvement in magnetic and dielectric properties of ferrites is of continuous inter... Among the family of ferrites, M-type hexaferrites has many industrial applications ranging from simple magnets to microwave devices. Improvement in magnetic and dielectric properties of ferrites is of continuous interest. In this present work details study is done to observe the effect of co-doping of rare-earth (RE3+: Pr3+, Sm3+, and Gd3+) and aluminum in Sr0.82RE0.18Fe12-xAlxO19 (x = 0.0, 0.5, 1.0, 1.5, 2.0). The adopted samples were synthesized via autocombustion technique. Detailed synthesis, structural, magnetic, and electrical measurements of samples were performed to understand structural-magnetic-electrical property relationship. The Al3+ substitution for Fe3+ brings in a significant enhancement in coercivity but reduces magnetization due to the magnetic dilution effect. Additional coercivity enhancement was possible with RE3+ doping without affecting the magnetization of samples. Among all RE3+ doped samples, Pr3+ doped samples showed the highest Curie temperature, (Tc ~ 465℃), while Gd3+ doped samples showed little variation in dielectric properties in GHz frequency range. This makes RE3+ doped samples as an ideal candidate for high-frequency microwave applications. Pr3+ with oblate charge distribution (negative Stevens constant) was observed to substitute well into the lattice consequently bringing in desired improvements in physical properties of Sr0.82RE0.18Fe12-xAlxO19 ferrite. 展开更多
关键词 SR-FERRITE Nanocomposite Magnetization CURIE Temperature Coercivity Dielectric Constant
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Regulating element distribution to improve magnetic properties of sintered Nd–Fe–B/Tb–Fe–B composite magnets
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作者 李柱柏 左敬燕 +2 位作者 王东山 刘飞 张雪峰 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第7期465-469,共5页
Nd content was varied in Nd13.2-xFe80.8+xB6(x = 0, 0.5, 1, and 1.5) to optimize the magnetic properties of sintered Nd–Fe–B/Tb–Fe–B composite magnets, which were prepared by mixing 9 g of Nd–Fe–B with 1 g of Tb1... Nd content was varied in Nd13.2-xFe80.8+xB6(x = 0, 0.5, 1, and 1.5) to optimize the magnetic properties of sintered Nd–Fe–B/Tb–Fe–B composite magnets, which were prepared by mixing 9 g of Nd–Fe–B with 1 g of Tb17Fe75B8 powder.In conventional magnets, by reducing Nd content, the coercivity of 10.4 kOe in Nd13.2Fe80.8B6 decreases to 7.2 kOe in Nd12.2Fe81.8B6;meanwhile, in Nd–Fe–B/Tb–Fe–B magnets the coercivity does not decrease when reducing Nd content.In the intergranular phase, the Tb content increases owing to the reducing Nd content of the Nd–Fe–B alloy in the sintered composite magnets.Therefore, the excess Tb in Tb17Fe75B8 enters the intergranular phase, and more Tb atoms can substitute for Nd at the grain boundary of the Nd–Fe–B phase, leading to a more significant increase in coercivity.The remanence increases with reducing Nd content, and the energy product of 39.1 MGOe with a high coercivity of 21.0 kOe is obtained in Nd12.2Fe81.8B6/Tb17Fe75B8 magnets.These investigations show that magnetic properties can be further improved by regulating the element distribution in sintered composite magnets. 展开更多
关键词 COMPOSITE MAGNETS COERCIVITY INTERGRANULAR phase element distribution
用于磁记录磁头的镍-铁-钨合金薄膜的制备及其性能 预览
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作者 张艳玲 席志军 《电镀与环保》 CAS CSCD 北大核心 2019年第4期4-6,共3页
采用电沉积方法制备了用于磁记录磁头的镍-铁-钨合金薄膜,并研究了钨酸钠的质量浓度对镍-铁-钨合金薄膜的成分、硬度、表面形貌及磁性能的影响。研究发现:随着钨酸钠的质量浓度的增加,镍-铁-钨合金薄膜中镍和钨的质量分数逐渐提高,而铁... 采用电沉积方法制备了用于磁记录磁头的镍-铁-钨合金薄膜,并研究了钨酸钠的质量浓度对镍-铁-钨合金薄膜的成分、硬度、表面形貌及磁性能的影响。研究发现:随着钨酸钠的质量浓度的增加,镍-铁-钨合金薄膜中镍和钨的质量分数逐渐提高,而铁的质量分数有所下降。镍-铁-钨合金薄膜是一种典型的晶态颗粒膜。增加钨酸钠的质量浓度,有利于提高镍-铁-钨合金薄膜的硬度和比饱和磁化强度。当钨酸钠的质量浓度为2 g/L时,镍-铁-钨合金薄膜的矫顽力最小,约为1.96 kA/m。 展开更多
关键词 电沉积 磁记录磁头 镍-铁-钨合金薄膜 矫顽力
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热处理工艺对超因瓦合金组织和磁性能的影响
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作者 于敏 蔡凯洪 牛宏凯 《金属材料研究》 2019年第2期38-41,共4页
本文选用改良后的超因瓦合金为研究对象,调整不同的热处理工艺,分析热处理工艺对合金组织以及磁性能的影响规律。研究发现,锻造态合金内部含有大量的析出物,随着热处理温度的升高,析出物逐渐的溶解;与此同时,随着热处理温度的升高,合金... 本文选用改良后的超因瓦合金为研究对象,调整不同的热处理工艺,分析热处理工艺对合金组织以及磁性能的影响规律。研究发现,锻造态合金内部含有大量的析出物,随着热处理温度的升高,析出物逐渐的溶解;与此同时,随着热处理温度的升高,合金的磁导率逐渐升高,矫顽力逐渐下降。 展开更多
关键词 超因瓦合金 热处理 磁导率 矫顽力
钕铁硼晶界扩散研究进展
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作者 谭敏 赵扬 +3 位作者 陈红升 席龙龙 李安华 冯海波 《粉末冶金工业》 CAS 北大核心 2019年第2期66-72,共7页
晶界扩散是通过热处理使扩散源沿晶界进入钕铁硼磁体内部以提高矫顽力的技术。该技术具有工艺简单、成本低廉、重稀土使用量少、能保持磁体的剩磁和磁能积基本不变,在制备小尺寸高矫顽力磁体时具有成本优势。对国内外研究成果进行了归... 晶界扩散是通过热处理使扩散源沿晶界进入钕铁硼磁体内部以提高矫顽力的技术。该技术具有工艺简单、成本低廉、重稀土使用量少、能保持磁体的剩磁和磁能积基本不变,在制备小尺寸高矫顽力磁体时具有成本优势。对国内外研究成果进行了归纳总结,介绍了矫顽力提高原理及各向异性扩散机制,详细讨论了涂覆方法以及扩散源对磁体矫顽力提高的影响,并对晶界扩散的发展趋势进行了展望。 展开更多
关键词 晶界扩散 矫顽力 涂覆方法 扩散源
用于微电机系统的Co-Pt-P磁性薄膜的制备 预览
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作者 孙鹏娇 《电镀与环保》 CAS CSCD 北大核心 2019年第3期4-6,共3页
使用电沉积方法制备了用于微电机系统的Co-Pt-P磁性薄膜。研究了次磷酸钠的浓度对薄膜的沉积速率、厚度、成分、表面形貌及磁性能的影响。结果表明:提高次磷酸钠的浓度,有利于加快沉积速率,提高薄膜中钴和磷的质量分数。Co-Pt-P磁性薄... 使用电沉积方法制备了用于微电机系统的Co-Pt-P磁性薄膜。研究了次磷酸钠的浓度对薄膜的沉积速率、厚度、成分、表面形貌及磁性能的影响。结果表明:提高次磷酸钠的浓度,有利于加快沉积速率,提高薄膜中钴和磷的质量分数。Co-Pt-P磁性薄膜是一种典型的瘤状颗粒膜。磷的析出有利于细化薄膜表面颗粒,限制畴壁位移,从而大大提高薄膜的矫顽力。然而,高浓度的次磷酸钠会破坏镀液的稳定性,使薄膜的磁性能下降。 展开更多
关键词 Co-Pt-P磁性薄膜 电沉积 矫顽力
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Ge添加对Fe基纳米晶软磁合金结构和性能的影响
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作者 孙亚明 牟喜悦 +2 位作者 王志群 徐仕翀 华中 《兵器材料科学与工程》 CAS CSCD 北大核心 2019年第5期90-93,共4页
采用单辊快淬法制备Fe81-xCoxZr7Mo2B10-yGey(x=10,40;y=0,1)系列非晶合金,在真空条件下对非晶合金在温度为525~625℃进行热处理。借助差热分析仪(DSC)、X射线衍射仪(XRD)、透射电镜(TEM)和振动样品磁强计(VSM)等进行合金的热性能、微... 采用单辊快淬法制备Fe81-xCoxZr7Mo2B10-yGey(x=10,40;y=0,1)系列非晶合金,在真空条件下对非晶合金在温度为525~625℃进行热处理。借助差热分析仪(DSC)、X射线衍射仪(XRD)、透射电镜(TEM)和振动样品磁强计(VSM)等进行合金的热性能、微观结构及磁性能分析。结果表明:添加Ge对低Co和高Co含量合金的热性能、微观结构、磁性能的影响不同;低Co合金,添加Ge可降低合金晶化峰值温度,增大α-Fe(Co)晶粒尺寸,促进晶粒均匀分布;高Co合金,Ge的添加对合金晶化峰值温度和α-Fe(Co)相晶粒尺寸影响不大;Ge添加与否对热处理后合金的矫顽力(Hc)值影响不大。 展开更多
关键词 非晶合金 Ge添加 晶粒尺寸 矫顽力
Coercivity mechanisms in nanostructured permanent magnets
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作者 赵国平 赵莉 +2 位作者 沈来川 邹静 邱雷 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第7期1-13,共13页
Coercivity mechanism in permanent magnets has been debated for many years.In this paper, various models of the coercivity mechanism are classified and re-examined by the comparison and contrast.Coherent rotation and c... Coercivity mechanism in permanent magnets has been debated for many years.In this paper, various models of the coercivity mechanism are classified and re-examined by the comparison and contrast.Coherent rotation and curling models can reveal the underlying reversal mechanism clearly based on isolated grains with elliptic shapes.By contrast, the numerical methods consider inter-grain interactions while simulating the evolution of the spins and hysteresis loops with complicated shapes.However, an exact simulation of magnetic reversal in permanent nanomagnets requires many meshes to mimic the thin domain wall well.Nucleation and pinning are the two main coercivity mechanisms in permanent magnets.The former signifies the beginning of the magnetic reversal, whilst the latter completes it.Recently, it is proposed that the large difference between the intrinsic magnetic properties of the nucleation centers and those of the main phase can result in a large pinning field(self-pinning), which has the attributes of both traditional nucleation and pinning.Such a pinning explains the experimental data of permanent magnets very well, including the enhancement of the coercivity by the grain boundary pinning. 展开更多
关键词 COERCIVITY mechanism PERMANENT NANOMAGNETS self-pinning
Grain boundary restructuring and La/Ce/Y application in Nd–Fe–B magnets
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作者 严密 金佳莹 马天宇 《中国物理B:英文版》 SCIE EI CAS CSCD 2019年第7期25-53,共29页
Since the 1980 s, Nd–Fe–B with largest energy product(BH)max approaching the theoretical limit has become the landmark of permanent magnetic material.The application spectrum for Nd–Fe–B continues to expand over t... Since the 1980 s, Nd–Fe–B with largest energy product(BH)max approaching the theoretical limit has become the landmark of permanent magnetic material.The application spectrum for Nd–Fe–B continues to expand over time both in the industrial and commercial sectors, which leads to growing research interests for solving the long-standing drawbacks of Nd–Fe–B, i.e., poor corrosion resistance, low coercivity, high Dy/Tb and low La/Ce/Y consumption.Concerning the above obstacles, we aim to present the novel grain boundary restructuring(GBR) approach, from GB design, processing, to structure evolution and property evaluation with a focus on the corrosion and coercivity mechanism of the restructured 2:14:1-typed magnets.Starting with an introduction to the fundamental of GBR, two representative examples,high-electrode-potential(Pr, Nd)32.5Fe62.0Cu5.5 and low-melting-point Dy71.5Fe28.5, are given with detailed descriptions of the advantages of GBR to enhance the intrinsic anti-corrosion stability and to strengthen the coercivity at low Dy consumption.Microstructure–property correlations are established to understand the critical importance of regulating the restructured GB phase to maximize the all-round performance of the 2:14:1-typed permanent magnets.Aiming at sustainable and balanced development of rare earth(RE) industry, the proceeding section proposes new prototypes of La–Ce and Y–Ce co-substitutions with dual benefits of stabilizing the 2:14:1 tetragonal phase and strengthening the intrinsic hard magnetism.The findings of additional REFe2 intergranular phase delight that the GBR approach also opens up a new horizon of research and application to develop high-performance La/Ce/Y-rich permanent magnets with deliberately tailored GB phase. 展开更多
关键词 GRAIN boundary RESTRUCTURING COERCIVITY corrosion resistance Dy/Tb La/Ce/Y
Dependence of magnetic properties on microstructure and composition of Ce-Fe-B sintered magnets
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作者 Longlong Xi Anhua Li +4 位作者 Haibo Feng Min Tan Wei Sun Minggang Zhu Wei Li 《中国稀土学报:英文版》 SCIE EI CAS CSCD 2019年第8期865-870,I0003共7页
In this paper,dependence of magnetic properties on microstructure and composition of Ce-Fe-B sintered magnets with Cu-doped Ce-rich alloy addition was investigated.It shows that the maximum energy product(BH)(max)and ... In this paper,dependence of magnetic properties on microstructure and composition of Ce-Fe-B sintered magnets with Cu-doped Ce-rich alloy addition was investigated.It shows that the maximum energy product(BH)(max)and coercivity H(cj)of Ce-Fe-B sintered magnet are improved from 6.76 to 9.13 MGOe by 35.1%,and from 1.44 to 1.67 kOe by 16.0%,respectively,via adding 5 wt%liquid phase alloy of Ce(35.58)Fe(57.47)Cu6 B(0.95)(at%).Compared with the magnet without Cerich alloy addition,the volume fraction of the grain-boundary phase with low melting point increases in the magnet with Ce-rich alloy additio n,which is be ne ficial to imp roving the microstructure and promoting the coercivity enhancement of the magnet.In the Ce-Fe-B magnet with Ce-rich alloy addition,Cu and Ce enrich in the grain boundaries of the magnet after annealing,therefore the as-annealed magnet has a higher coercivity than the as-sintered magnet.A distinct Fe-rich layer with the average thickness of 60 nm is found in the grain boundaries in the magnet without Ce-rich alloy addition,but it seems that Fe-rich phase disappears in the magnet with Ce-rich alloy addition.The present work suggests that the further improvement of coercivity in the Ce-Fe-B sintered magnets is expectable by designing the composition and structure of added liquid phase alloys. 展开更多
关键词 Ce-Fe-B Ce-rich liquid phase alloy Cu DOPING MICROSTRUCTURE COERCIVITY Rare earths
粉末粒度对烧结钕铁硼磁体组织和磁性能的影响
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作者 付建龙 李泉 +4 位作者 刘国征 赵明静 高岩 鲁富强 周博阳 《稀土》 EI CAS CSCD 北大核心 2019年第2期57-62,共6页
通过调节气流磨分级轮转速控制粉末粒度,对烧结后NdFeB磁体的磁性能和微观组织进行分析,研究粉末粒度对磁体磁性能和微观组织的影响。实验结果表明,磁体的内禀矫顽力随着粉末粒度的降低逐渐增加;合金粉末的平均粒径从3.26μm减小至2.91... 通过调节气流磨分级轮转速控制粉末粒度,对烧结后NdFeB磁体的磁性能和微观组织进行分析,研究粉末粒度对磁体磁性能和微观组织的影响。实验结果表明,磁体的内禀矫顽力随着粉末粒度的降低逐渐增加;合金粉末的平均粒径从3.26μm减小至2.91μm,磁体的内禀矫顽力可以增加4.9%;最佳烧结温度随着粉末平均粒径的减小而降低。 展开更多
关键词 烧结钕铁硼 粉末粒度 矫顽力
Improving the hard magnetic properties by intragrain pinning for Ta doped nanocrystalline Ce-Fe-B alloys
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作者 J.S.Zhang W. Li +5 位作者 X.F. Liao H.Y. Yu L.Z. Zhao H.X. Zeng D.R. Peng Z.W. Liu 《材料科学技术学报:英文版》 SCIE EI CAS CSCD 2019年第9期1877-1885,共9页
To develop Ce based permanent magnets with high performance/cost ratio, Ta doping is was employed to enhance the magnetic performance of Ce-Fe-B alloys. For melt spun Cei7Fe78-xTaxB6 (x = 0-1) alloys, the coercivity H... To develop Ce based permanent magnets with high performance/cost ratio, Ta doping is was employed to enhance the magnetic performance of Ce-Fe-B alloys. For melt spun Cei7Fe78-xTaxB6 (x = 0-1) alloys, the coercivity Hc increases from 439 to 553 kA/m with increasing x value from 0 to 0.75. Microstructure characterizations indicate that Ta doping is helpful for grain refinement. A second phase of TaB2 is observed in Ce17Fe77.25Tao.75B6 alloy, which acts as the pinning center of the magnetic domains, resulting in the change of coercivity mechanism from nucleation type to nucleation +pinning type. The micromagnetic simulation confirms that non-magnetic particles within hard magnetic phase can increase the demagnetization field around them and it is crucial for preventing the further magnetization reverse by pinning effect. Take the advantage of Ta doping for enhancing the coercivity, Ce content of Ce-Fe-B alloy can be further cut down to increase the remanence Jr due to the reduced volume fraction of CeFe2 phase and increased Fe/Ce ratio. As a result, a good combination of magnetic properties with Hc = 514 kA/m, Jr = 0.49 T, and the maximum energy product (BH)max = 36 kJ/m^3 have been obtained in Ce15Fe79.25Tao.75B6 alloy. It is expected that the present work can serve as a useful reference for designing new permanent magnetic materials with low-cost. 展开更多
关键词 MELT-SPINNING PERMANENT MAGNETS Second phase COERCIVITY mechanism Thermal stability
An overview on nucleation theories and models
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作者 Marcos Flavio de Campos Jose Adilson de Castro 《中国稀土学报:英文版》 SCIE EI CAS CSCD 2019年第10期1015-1022,共8页
Several different models for coercivity are discussed. There are two main situations: i) nanocrystalline magnets, with grain size bellow the single domain particle size, and ii) magnets with grain size above single do... Several different models for coercivity are discussed. There are two main situations: i) nanocrystalline magnets, with grain size bellow the single domain particle size, and ii) magnets with grain size above single domain particle size. The described theories and models are general, and can be applied in either NdFeB magnets, SmFeCoCuZr or strontium ferrite magnets. The spring effect observed in isotropic nanocrystalline magnets can be explained with the Stoner-Wohlfarth model. Modifications of the StonerWohlfarth model are necessary to take into account the effect of interaction between grains. When the grain size is above the single domain size, energy considerations show that nucleation should occur at the surface of grains. Nucleation is interpreted as a two-step process, where domain wall displacement occurs for grain size above single domain size, after a nucleus is first formed. The effect of grain size on the coercive field is discussed. 展开更多
关键词 COERCIVITY NUCLEATION GRAIN size Spring effect ND-FE-B PERMANENT MAGNET
A hybrid coercivity mechanism for exchange-coupled nanocomposite permanent magnets
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作者 Lei Qiu Li Zhao +4 位作者 Xiaojiao Weng Laichuan Shen Guoping Zhao Fang Wang Linhua Xie 《中国稀土学报:英文版》 SCIE EI CAS CSCD 2019年第10期1030-1033,共4页
We propose a hybrid coercivity mechanism for exchange-coupled hard/soft multilayers, which incorporates elements of both the traditional nucleation and pinning mechanisms based on both threedimensional(3 D) and one-di... We propose a hybrid coercivity mechanism for exchange-coupled hard/soft multilayers, which incorporates elements of both the traditional nucleation and pinning mechanisms based on both threedimensional(3 D) and one-dimensional(1 D) micromagnetic calculations. The magnetic reversal starts with the nucleation of the domain wall near the defects or soft phases, which ends by the pinning usually in the same place. Therefore, pinning near the nucleation centers are the dominant coercivity mechanism for both exchange-coupled nanocomposites and so-called single-phased permanent magnets. Our proposed coercivity mechanism and calculated results agree very well with available experimental data,especially the recently reported high energy products achieved in NdFeB and SmCo based hard/soft multilayers. The hybrid coercivity mechanism can be readily extended to single-phased permanent magnets with defects and other magnetic systems. 展开更多
关键词 COERCIVITY mechanism Hard/soft MULTILAYERS HYBRID model MICROMAGNETICS Rare earths
钼酸钠对电沉积Co-Pt-Mo磁性薄膜性能的影响 预览
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作者 李晓芳 谭菊华 郭小春 《电镀与环保》 CAS CSCD 北大核心 2019年第6期33-35,共3页
在纯铜表面制备了Co-Pt-Mo磁性薄膜,并研究了钼酸钠的质量浓度对Co-Pt-Mo磁性薄膜性能的影响。结果表明:随着钼酸钠的质量浓度的增加,Co-Pt-Mo磁性薄膜的厚度和电流效率显著提高,钴和钼的质量分数逐渐增大,使得比饱和磁化强度增大。然而... 在纯铜表面制备了Co-Pt-Mo磁性薄膜,并研究了钼酸钠的质量浓度对Co-Pt-Mo磁性薄膜性能的影响。结果表明:随着钼酸钠的质量浓度的增加,Co-Pt-Mo磁性薄膜的厚度和电流效率显著提高,钴和钼的质量分数逐渐增大,使得比饱和磁化强度增大。然而,当钼酸钠的质量浓度为10 g/L时,由于剧烈的析氢和金属氢氧化物胶体的阻碍作用,使得电流效率下降,Co-Pt-Mo磁性薄膜表面的颗粒发生团聚现象,孔隙率增大,矫顽力降低。当钼酸钠的质量浓度为8 g/L时, Co-Pt-Mo磁性薄膜具有致密的结构和最大的矫顽力。 展开更多
关键词 Co-Pt-Mo磁性薄膜 电沉积 矫顽力
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磁通变换器高低温失效后的改进设计 预览
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作者 张广智 朱华 龚祚勇 《电器与能效管理技术》 2019年第5期28-33,共6页
面对新能源配电系统越来越严酷的应用环境需求,磁通变换器作为万能式断路器和塑壳断路器的智能控制器中最重要的执行元件,其性能要求也随之提高。通过磁通变换器高低温试验失败后的失效模式分析,确定永磁铁为主要失效零件,结合电磁仿真... 面对新能源配电系统越来越严酷的应用环境需求,磁通变换器作为万能式断路器和塑壳断路器的智能控制器中最重要的执行元件,其性能要求也随之提高。通过磁通变换器高低温试验失败后的失效模式分析,确定永磁铁为主要失效零件,结合电磁仿真及高低温试验,对结果进行比较,验证选材的正确性,从而为磁通变换器的持续优化提供理论及实践依据。 展开更多
关键词 磁通变换器 永磁铁 电磁仿真 矫顽力 磁感应强度
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High coercivity Nd-Ce-Fe-B nanostructured ribbons prepared from melt spinning technique
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作者 Liang Zha Zhou Liu +11 位作者 Hao Chen Mingzhu Xue Guanyi Qiao Shilei Ding Xin Wen Meiling Zhang Youfang Lai Wenyun Yang Jingzhi Han Dong Zhou Chenyao Zhu Jinbo Yang 《中国稀土学报:英文版》 SCIE EI CAS CSCD 2019年第10期1053-1058,共6页
The Ce-substituted(Nd1-xCex)12.2 Fe81.6 B6.2(x=0.0, 0.2, 0.4, 0.6) nanocrystalline ribbons were prepared by annealing amorphous ribbons from melt spinning. It is found that all ribbons are in a multiphase state consis... The Ce-substituted(Nd1-xCex)12.2 Fe81.6 B6.2(x=0.0, 0.2, 0.4, 0.6) nanocrystalline ribbons were prepared by annealing amorphous ribbons from melt spinning. It is found that all ribbons are in a multiphase state consisting of a-Fe phase, Nd(Ce)-rich phases and RE2 Fe14 B(RE = Nd, Ce) phases. However, the coercivity of all annealed ribbons can reach a considerably high value without doping any heavy rare earth or other coercivity enhanced elements. A strong intergranular exchange coupling appears in these nanocrystalline ribbons. The Nd12.2 Fe81.6 B6.2 ribbons with multiphase have a coercivity of about 11.3 k Oe, and the coercivity decreases slightly with increasing Ce content. A coercivity of 7.5 kOe can be obtained when60 at% of Nd is replaced by Ce(x = 0.6) due to the grain refinement and the strong intergranular exchange coupling. This provides a practical approach of fabricating high coercivity Ce-substituted Nd-Fe-B materials. 展开更多
关键词 ND-FE-B alloy Ce SUBSTITUTION COERCIVITY RARE earths
Coercivity kinetics upon step annealing of sintered Sm(Co0.88-xFexCu0.09Zr0.03)7 magnets
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作者 A.G.Popov O.A.Golovnia +3 位作者 A.V.Protasov V.S.Gaviko D.A.Kolodkin R.Gopalan 《中国稀土学报:英文版》 SCIE EI CAS CSCD 2019年第10期1059-1065,共7页
Behavior of the coercivity of the high-temperature Sm(Co0.88-xFexCu0.09Zr0.03)7 magnets depending on the temperature and time of annealing with the temperature decreasing stepwise from 700 to 400℃ was investigated.It... Behavior of the coercivity of the high-temperature Sm(Co0.88-xFexCu0.09Zr0.03)7 magnets depending on the temperature and time of annealing with the temperature decreasing stepwise from 700 to 400℃ was investigated.It is shown that the growth rate of coercivity abruptly increases at the initial stage of annealing in the vicinity of the Curie temperature of the SmCo5 phase.The origin of the effect is the counter diffusion of Cu and Co atoms through dislocation tubes,which form because of enhanced stresses and a partial breakage of coherent coupling at the interface of the Sm2 Co17 and SmCo5 phases.Diffusive enrichment of the SmCo5 phase in Cu close to the interface with Sm2 Co17 leads to relaxation of stresses and increases in the gradient of the magnetic domain-wall energy and coercivity. 展开更多
关键词 Sm-Co-Fe-Cu-Zr Permanent magnet SM2CO17 SMCO5 COERCIVITY KINETICS
晶界扩散Dy-Al-Ga对钕铁硼磁体的磁性能和微观组织的影响 预览
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作者 屈鹏鹏 曾亮亮 +3 位作者 黄祥云 何磊 杜畅 李家节 《有色金属科学与工程》 CAS 2019年第3期64-68,共5页
通过晶界扩散Dy70Al10Ga20合金研究了烧结Nd-Fe-B磁体的磁性能和热稳定性能.用NIM-500C高温永磁测量仪和MLA650扫描电镜测出了磁体在扩散前后的磁性能和微观组织的变化.结果表明,在Dy70Al10Ga20合金扩散热处理后,磁体矫顽力从原始的1080... 通过晶界扩散Dy70Al10Ga20合金研究了烧结Nd-Fe-B磁体的磁性能和热稳定性能.用NIM-500C高温永磁测量仪和MLA650扫描电镜测出了磁体在扩散前后的磁性能和微观组织的变化.结果表明,在Dy70Al10Ga20合金扩散热处理后,磁体矫顽力从原始的1080.968kA/m显著提升到1671.600kA/m,提升幅度约为55%,而剩磁下降很少.Dy、Al、Ga元素在晶界处扩散,很好地隔绝了磁交换作用,提升矫顽力.SEM图显示在扩散Dy70Al10Ga20合金后,可以很明显地看到晶粒外延层有一层灰色的壳层包覆着主相晶粒,很好地起到了隔离晶粒的磁交换作用.XRD显示主相的峰普遍往右偏移,这归因于重稀土元素Dy进入晶粒外延层形成(Nd,Dy)2Fe14B核壳结构.Dy的原子半径比Nd小,导致峰往右移. 展开更多
关键词 晶界扩散 低熔点合金 烧结钕铁硼 矫顽力
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氧含量对烧结钕铁硼磁体Dy晶界扩散的影响
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作者 程星华 李建 +3 位作者 周磊 刘涛 喻晓军 李波 《稀有金属材料与工程》 SCIE EI CAS CSCD 北大核心 2019年第6期2009-2013,共5页
主要研究了烧结钕铁硼磁体中氧含量对Dy晶界扩散后的Dy含量及矫顽力的影响。比较了多种高、低氧磁体Dy扩散后的性能,发现低氧磁体的Dy扩散量和矫顽力提高量均明显高于高氧磁体。对9个0%Dy的不同氧含量样品进行扩散再次发现,氧含量减少... 主要研究了烧结钕铁硼磁体中氧含量对Dy晶界扩散后的Dy含量及矫顽力的影响。比较了多种高、低氧磁体Dy扩散后的性能,发现低氧磁体的Dy扩散量和矫顽力提高量均明显高于高氧磁体。对9个0%Dy的不同氧含量样品进行扩散再次发现,氧含量减少有利于Dy扩散量、矫顽力的提高。渗透后的各样品Dy成分梯度结果显示,低氧磁体的Dy扩散量由表及里全面高于高氧磁体,内外浓度梯度也小于后者。电子探针表征结果表明,低氧磁体Dy扩散后晶界处Dy富集条纹更明显、连续,完整包裹各个主相晶粒。这种结构优化也使低氧磁体各向异性场提高幅度大于高氧磁体。这是因为磁体中氧含量降低使富钕相在主相周边均匀连续分布,为后续进入磁体内部的Dy元素提供连续的扩散通道,从而使磁体的Dy扩散量和矫顽力进一步提高。 展开更多
关键词 烧结钕铁硼 Dy蒸镀扩散 低氧磁体 Dy含量 矫顽力
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