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Magnetic Properties of Nanostructured Rare Earth-Fe Compound Produced by HDDR Process

HDDR 工艺生产的纳米结构稀土铁化合物的磁性能

基本信息

批准号：
10555240
负责人：
SUGIMOTO Satoshi
金额：
$ 3.84万
依托单位：
TOHOKU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10555240/
关键词：
HDDR 3:29 phase permanent magnets disproportionation TbCuィイD27ィエD2 type phase Sm_3(Fe.V)_<29>化合物

项目摘要

Purpose : Remanence enhanced magnets made from a 2 phase nanostructure of hard and soft magnetic phases, can be prepared by either melt spinning or by mechanical alloying. Our previous work has shown that a 2 phase mixture can also be obtained by the Hydrogenation Disproportionation Desorption Recombination (HDDR) processing of Sm3(Fe,V)29 into TbCu7 type and αFe(V) phases, which exhibits coercivities of about 0.6 MAmィイD1-1ィエD1 (7kOe) after nitriding. However, the grain size of HDDR processed materials (〜300 nm) is typically an order of magnitude larger than that necessary for remanence enhancement to occur : the soft grains should ideally be 10 - 20 nm. The addition of Co has been shown to be effective in reducing the recombination temperature and grain size of HDDR treated samples. Therefore, the aim of this work was to investigate the effect of Co on the disproportionation and recombination kinetics of Sm3(Fe,V)29, and to attempt to reduce the grain size of the aFe(Co,V)/TbCu7 type … More phase mixture.Experimental Procedure : Alloys of Sm9.4Fe84.6-XCoXV6.0 (X=0, 10, 20 and 30), were induction melted from high purity elements, under an Ar atmosphere, and then homogenized at 1150℃ for 20 hours. X-ray diffraction (XRD) analysis showed that the alloys were near single phase Sm3(Fe,Co,V)29 with a small amount of aFe(Co,V). The homogenized alloys were ground into powders, sieved to a particle size less than 63μm, and pressed into green compacts. Samples were obtained at different stages of the disproportionation reaction, by heating under hydrogen to temperatures between 620 - 700℃, and then after 1 hour, cooling rapidly in hydrogen. HDDR samples were obtained by heating the disproportionated samples under vacuum to temperatures between 590 - 750℃, and then after 10 min - 12 hours, cooling rapidly under vacuum. Some of the HDDR samples were then nitrided at 560℃ for 4 hours 3), then ground into powder, which was mixed with molten paraffin that solidified within a magnetic field of 1.0 MAm-1(12 kOe). The magnetic properties were measured using a vibrating sample magnetometer (VSM). Samples for transmission electron microscopy (TEM) were thinned by ion milling.Results : with the addition of cobalt, the disproportionation temperature of the alloys Sm9.4Fe84.6-XCoXV6.0 (X=0, 10, 20, 30) increased, and the recombination temperature decreased. This shows that cobalt stabilizes the Sm3(Fe,Co,V)29 phase with respect to disproportionation in hydrogen, and increases the rate of the recombination into aFe(Co,V) and TbCu7 type phases. With TEM 【approximately equal】5 nm diameter rods were observed, which are believed to be SmH2. Grains about 50-100 nm in size were found in a 30% Co sample recombined at 630℃ for 1 hour. In addition to aFe(Co,V) and TbCu7 type phases, XRD also showed the presence of a yet unidentified phase that forms at high Co contents and low temperatures, which appeared to have an adverse effect on the magnetic properties, after nitriding. Less

目的：利用软硬两相纳米结构制备剩磁增强磁体，可采用熔体纺丝或机械合金化制备剩磁增强磁体。我们之前的研究表明，Sm3(Fe，V)29的氢化歧化解吸复合（HDDR）处理也可以得到TbCu7型和αFe(V)相的2相混合物，氮化后的矫顽力约为0.6 m_ (γ γ γ γ) -1 - γ (γ γ γ)。然而，HDDR加工材料的晶粒尺寸（~ 300 nm）通常比发生剩余物增强所需的晶粒尺寸大一个数量级：理想的软晶粒尺寸应为10 - 20 nm。Co的加入可以有效降低HDDR处理样品的复合温度和晶粒尺寸。因此，本研究的目的是研究Co对Sm3(Fe，V)29歧化和重组动力学的影响，并试图减小aFe(Co，V)/TbCu7型…More相混合物的晶粒尺寸。实验步骤：将Sm9.4Fe84.6-XCoXV6.0合金（X= 0,10,20和30）在氩气气氛下由高纯元素感应熔化，然后在1150℃下均质20小时。x射线衍射（XRD）分析表明，合金接近单相Sm3(Fe,Co，V)29，并含有少量的aFe（Co，V）。将均匀化的合金研磨成粉末，筛分至粒径小于63μm，压制成绿色压坯。在歧化反应的不同阶段，将样品在氢气下加热至620 - 700℃，然后在氢气中快速冷却1小时。歧化后的HDDR样品在真空下加热至590 ~ 750℃，10 min ~ 12 h后在真空下快速冷却。将部分HDDR样品在560℃下渗氮4小时3)，研磨成粉末，与熔融石蜡混合，在1.0 MAm-1（12 kOe）的磁场下固化。用振动样品磁强计（VSM）测量了其磁性能。透射电子显微镜（TEM）用离子磨薄样品。结果：随着钴的加入，合金Sm9.4Fe84.6-XCoXV6.0 （X=0、10、20、30）的歧化温度升高，复合温度降低。这表明钴在氢中的歧化作用稳定了Sm3(Fe,Co，V)29相，提高了其复合为aFe（Co，V）和TbCu7型相的速率。透射电镜（TEM）观察到直径约为5 nm的棒状物，认为是SmH2。30% Co样品在630℃下复合1小时，晶粒尺寸约为50 ~ 100 nm。除了aFe（Co，V）和TbCu7型相外，XRD还发现在高Co含量和低温下形成的一种尚未确定的相，这种相对氮化后的磁性能有不利影响。少