Sm2(Fe,M)17Nx稀土永磁材料的研究进展

综述了Sm2(Fe，M)17Nx永磁材料的最新研究进展，介绍了Sm2(Fe，M)17Nx磁粉及磁体的制备技术，说明用其他元素替换Sm或Fe对材料性能的影响，以及粉末颗粒具有最佳的尺寸和形貌的重要性。并指出放电等离子烧结技术(SPS)有望成为制备Sm2(Fe，M)17Nx致密磁体的一个有效方法。     

金属间化物（Sm_（1－x）Dy_x）_2Fe_（17）N_y中的各向异性机制探讨

本文主要通过变温穆斯堡尔谱等手段研究金属间化物（Ｓｍ（１－ｘ）Ｄｙｘ）２Ｆｅ（１７）Ｎｙ（ｘ＝０．４；２＜ｙ＜３）的自旋重取向现象，进而对其中的各向异性产生机制进行分析。由实验结果得出Ｄｙ次格子的单轴各向异性较强，导致在１５０Ｋ～１００Ｋ较低温度下出现自旋重取向现象。     

Corrosion mechanism of H_2O on Sm_2Fe_(17) and nitrogenation process of corroded Sm_2Fe_(17)

Sm_2 Fe_(17) prepared by reduction-diffusion method needs to be washed with water to remove calcium oxide. Electrochemical corrosion occurs when Sm_2 Fe_(17) powder is in contact with liquid water. Corrosion mechanism of H_2 O on Sm_2 Fe_(17) powder and nitrogenation process of corroded Sm_2 Fe_(17) were studied by analyzing the structure and morphology. It is indicated that the metallic hydroxide forms and deposits on the Sm_2 Fe_(17) powder surfaces during water corrosion. At the same time, oxygen and hydrogen enter the unit cell of Sm2 Fe_(17), causing a slight increase in Curie temperature. In the subsequent nitriding process,the hydroxide is dehydrated and hydrogen is desorbed. The resulting oxide reacts with Sm_2 Fe_(17)N_x to form a-Fe and Sm_2 O_3. Thermodynamic calculations using the HSC Chemistry 6.0 software indicate that the reaction can occur spontaneously. The effect of water corrosion on the magnetic properties of the nitride can be eliminated by hydrogen reduction prior to nitriding.     

稀土永磁体的新应用

介绍了稀土永磁体在电机、减振器、磁选机、研磨、生产传输线等方面的最新应用趋势。     

Enhanced maximum energy product of(Sm_(1-y)Y_y)_2Fe_(17)N_x caused by abundant yttrium doping

Replacement of samarium(Sm) with abundant yttrium(Y) can help solve the potential shortage of Sm in the preparation of promising Sm_2 Fe_(1)7 N_x magnets.In this article,phase composition,microstructure and magnetic properties of(Sm_(1-y)Yy)_2 Fe_(17)N_x(y=0,0.2,0.4,0.6,0.8,1.0) were investigated.Maximum energy product(BH)_(max) is improved when less than 40 at% Y is doped in(Sm_(1-y)Y_y)_2 Fe_(17)N_x powder.In particular,when 20 at% Y replaces Sm,(BH)_(max) of(Sm_(1-y)Y_y)_2 Fe_(17)N_x powder increases by 15.1% from 131.7 to151.6 kJ/m~3.The effect of annealing temperature on the structural properties of high Y doping(Sm_(0.6)Y_(0.4))_2 Fe_(17) and the magnetic properties of the corresponding nitrides were subsequently investigated.In the RE_2 Fe_(17) phase grain combination process,the interlaced structure of the rhombohedral Th_2 Zn_(17)-type structural phase and the hexagonal Th_2 Ni_(17)-type structural phase is formed.Due to shortrange exchange coupling,the nitride with the highest content of two interlaced RE_2 Fe_(1)7 phases has the highest magnetic properties:B_r=1.23 T,H_(cJ)=443.9 kA/m and(BH)_(max)=197.6 kJ/m~3.     

HREM Study on Sm(Co,Fe,Cu,Ti)_7 Alloy Aged under Different Conditions

ＨＲＥＭＳｔｕｄｙｏｎＳｍ（Ｃｏ，Ｆｅ，Ｃｕ，Ｔｉ）_７ＡｌｌｏｙＡｇｅｄｕｎｄｅｒＤｉｆｆｅｒｅｎｔＣｏｎｄｉｔｉｏｎｓＬｉｕＡｎｓｈｅｎｇ（刘安生）（ＧｅｎｅｒａｌＲｅｓｅａｒｃｈｉｎｓｔｉｔｕｔｅｆｏｒＮｏｎ－ｆｅｒｒｏｕｓＭｅｔａｌｓ，Ｂｅｉ?..     

Enhanced magnetic properties of anisotropic Nd-Fe-B nanocomposites by Fe(C)coating

Nanostructured anisotropic Nd-Fe-B/Fe(C) composite powders were prepared by coating Fe(C) softmagnetic nanoparticles on HDDR Nd-Fe-B hard magnetic powders using iron pentacarbonyl Fe(CO)_5 as soft-phase precursor.The effect of Fe(CO)_5-loading amount on soft-phase purity,coating morphology and magnetic properties of the composite powders was investigated.Dense and continuous Fe(C) softphase coatings with average particle sizes of 58-68 nm are obtained at Fe(CO)_5 loading amounts of x 12 wt%,leading to enhanced remanence and improved energy product of the coated powders.Positive value in δM-plots and single-phase-like demagnetization curves are observed in the Nd-Fe-B/Fe(C) composite powders,indicating the exchange coupling effect between the coated Fe(C) soft phases and the Nd-Fe-B hard phase.     

Sm_2Co_(17)型高温永磁材料的性能及应用

阐述了Sm_2Co_(17)型永磁材料的高温磁性能和应用前景。从温度内补偿的角度出发,用重稀土金属Er部分地取代Sm_2(Co,Cu,Fe,Zr)_(7.22)中的Sm,可以有效地降低材料的温度系数,获得在高温下使用的高性能永磁材料。讨论了磁体在高温老化处理后回复到室温的磁性能变化及磁体长径比与温度稳定性的关系。     

Coercivity kinetics upon step annealing of sintered Sm(Co_(0.88-x)Fe_xCu_(0.09)Zr_(0.03))_7 magnets

Behavior of the coercivity of the high-temperature Sm(Co_(0.88-x)Fe_xCu_(0.09)Zr_(0.03))_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 SmCo_5 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 Sm_2 Co_(17) and SmCo_5 phases.Diffusive enrichment of the SmCo_5 phase in Cu close to the interface with Sm_2 Co_(17) leads to relaxation of stresses and increases in the gradient of the magnetic domain-wall energy and coercivity.     

Preparation and magnetic properties of anisotropic Nd_2Fe_(14)B/Sm_2Co_(17) hybrid-bonded magnets

In the present work, anisotropic Nd_2 Fe_(14) B/Sm_2 Co_(17) hybrid-bonded magnets were prepared with different Nd-Fe-B contents. It is found that the particle distributions and ratios between the two magnetic phases have important roles in the magnetic properties, microstructures and thermal stability of the magnets. With increase of Nd-Fe-B content, the saturation magnetization of the anisotropic hybrid magnet increases significantly, however, coercivity decreases, and the demagnetization curves show magnetically single-phase behavior. The anisotropic Nd_2 Fe_(14) B/Sm_2 Co_(17) hybrid-bonded magnets exhibit a maximum energy product and remanence of 14.15 MGOe and 99.53 A·m~2/kg, respectively, when the NdFe-B content is 70 wt% at room temperature. Furthermore, the hybrid magnets also have better thermal stability at elevated temperatures due to the interaction between the two magnetic particles.     

烧结温度对高矫顽力Sm2(Co,Fe,Cu,Zr)17永磁体磁性能的影响

为深入了解高矫顽力Sm2(Co,Fe,Cu,Zr)17永磁体烧结温度与磁体磁性能的关系，设计了6种不同烧结温度，分别测试了各温度下烧结试样的密度和磁性能。试验结果表明：高矫顽力Sm2(Co,Fe,Cu,Zr)17磁体的密度随着烧结温度的升高而升高，在1210－1220℃达到最大值；磁体在1205－1210℃烧结时有较高的磁性能，内禀矫顽力超过1910kA/m，最大磁能积达到210kJ/m^3，温度过高或过低都使磁本性能下降；剩磁Br随磁体密度的升高而上升，矫顽力Hci的变化是密度和晶粒大小及胞状尺寸综合作用的结果。     

Novel synthesis of single-crystalline TbCu7-type Sm–Fe powder by low-temperature reduction-diffusion process using molten salt

In this study, molten salt was used as a solvent for calcium (Ca) to let a reduction-diffusion (R-D) reaction occur below the melting point of Ca (1115 K), which is the lower limit temperature of the conventional R-D process. When the R-D reaction is conducted below 923 K with LiCl molten salt, submicron-sized TbCu₇-type Sm–Fe powder is formed. The c/a ratio of the powder estimated by a synchrotron X-ray diffraction pattern is 0.8456, which is consistent with the Sm_0.67Fe_5.667(SmFe_8.5) phase. An electron backscatter diffraction analysis reveals that single-crystalline TbCu₇-type SmFe_8.5 powder was synthesized for the first time.     

十年来上海稀土工业的进展

本文回顾了上海稀土工业的建立和发展,特别是近十年来的进展情况。对萃取和离子交换等现代分离技术,和稀土金属冶炼、稀土永磁材料、稀土发光材料等以及稀土在玻陶工业的应用均有所叙述。对上海稀土工业的未来亦进行了讨论。     

Structure and Magnetic Properties of Sm2Fe17Nx Sintering Magnets Prepared by Spark Plasma Sintering

Bulk Sm2Fe17Nx sintering magnet was fabricated by spark plasma sintering(SPS) technique. The effects of sintering pressure and sintering temperature on the magnetic properties of the Sm2Fe17Nx magnet were investigated. As a result, the density of the magnet is obviously improved with the increase of sintering pressure, but the coercivity drops since Sm2Fe17Nx has decomposed into SmN, α-Fe and N2. When sintering temperature was only above 200 ℃ under 1 GPa sintering pressure, the coercivity even begins to decrease, which indicates that high pressure promotes the decomposition of the Sm2Fe17Nx at lower temperature. The decomposition is also proved by the decrease of nitrogen and increase of α-Fe in the magnets.     

2∶17型Sm-Co高温永磁体的研究

用粉末冶金工艺制备了Sm(CobalFevCu0 .0 88Zr0 .0 2 5) 7.5(v =0～ 0 .3 0 )烧结磁体 ,通过系统研究Fe含量对磁体的室温及高温磁性的影响 ,制备出了具有很好的高温稳定性的永磁材料Sm(CobalFe0 .0 7Cu0 .0 88Zr0 .0 2 5) 7.5,在 5 0 0℃时其磁性能为 :Br=0 .687T ,bHC=42 9.7kA·m- 1 ,iHC=63 7 4kA·m- 1 ,(BH) max=83 .7kA·m- 1 。比较了该材料与商业用高矫顽力Nd Fe B和高矫顽力 2∶17型Sm Co磁体的高温磁性。     

轻稀土镧取代M型钡铁氧体超微粉末的合成与表征

利用溶胶-凝胶自蔓延高温合成法制备了稀土镧掺杂钡铁氧体BaLaxFe12-xO19超微粉末。讨论了起始溶液pH值、柠檬酸配比、煅烧温度等对粉末性能参数的影响。用X射线衍射仪、扫描电子显微镜和振动样品磁强计等对粉末的结构、形貌和磁学性能进行了研究。     

Nd2Fe14B/Fe3B基纳米复合粘结磁体的磁特性

通过实验研究了Nd2Fe14B／Fe3B双相纳米复合磁粉分别与几种不同性能的磁粉复合成粘结磁体后磁性能的变化。通过对复合磁体的理论分析得知，由Nd2Fe14B／Fe3B与RE2Fe14B或铁氧体磁粉复合成的粘结磁体中，成分间并未发生化学反应。以Nd2Fe14B／Fe3B铁氧体复合粘结磁体为例，根据理论分析推出的剩磁Br-成分含量关系曲线与实际曲线吻合得很好，表明剩磁与成分含量间存在着近似的线性关系，从而可通过数学手段建立磁性能参数与成分含量的函数关系式，用于简化混粉工艺。另外，添加铁氧体可对该复合磁体较差的热稳定性起到补偿作用，并减少了磁不可逆损失。     

NIR emitting terephthalates(Sm_xDy_yGd_(1-x-y))_2(tph)_3(H_2O)_4 for luminescence thermometry in the physiological range

The first luminescence thermometer based on coordination compound of samarium and dysprosium is repo rted.High luminescence intensity and high signal resolution are reached thanks to the concentration quenching reduction due to the use of the trimetallic complexes of Sm-Dy-Gd.The best thermometric properties in a wide temperature range among the studied systems are demonstrated by(Sm_(0.2)Dy_(0.15)Gd_(0.65))_2(tph)3(H_2 O)_4.The sensitivity reaches 0.5%/K in visible range and 1.2%/K in NIR range at low temperatures and 0.5%/K and 0.8%/K in physiological range.     

Rare earth permanent magnets Sm2(Co,Fe,Cu,Zr)17 for high temperature applications

Sintered Sm(CobalFexCu0.1Zr0.03)7.5 (x=0.09-0.21) permanent magnets with higher Fe content were found to have higher remanence Br and maximum energy product (BH)max at room temperature. Br and (BH)max reached maximum of 0.96 T and 176.7 kJ/m3, respectively at room temperature when the Fe content x reached 0.21. However, the intrinsic coercivity Hci at room temperature increased gradually when the Fe content x increased from 0.09 to 0.15, but when x further increased to 0.21, Hci decreased. Hci attained its peak value of 2276.6 kA/m with Fe content x=0.15 at room temperature. For magnets with x=0.15, Br, (BH)max and Hci reached 0.67 T, 81.2 kJ/m3 and 509.4 kA/m at 500℃, respectively, showing good high temperature stability, which could be used in high temperature applications.