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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：由硬磁相和软磁相组成的两相纳米结构制成的剩磁增强型磁体，可以通过熔体旋压或机械合金化的方法制备。我们以前的工作表明，Sm_3(Fe，V)_(29)经氢化歧化-解吸复合处理成TbCu7型和αFe(V)相也可以得到两相混合物，氮化后的矫顽力约为0.6mAmィイD_(-1)ィエD_1(7kOe)。然而，HDDR加工材料的颗粒尺寸(~300 nm)通常比剩磁增强所需的颗粒尺寸大一个数量级：理想情况下，软颗粒应该为10-20 nm。结果表明，Co的加入有效地降低了HDDR处理样品的复合温度和晶粒度。因此，本工作的目的是研究Co对Sm3(Fe，V)29歧化和复合动力学的影响，并试图减小aFe(Co，V)/TbCu7型…的晶粒度实验步骤：将Sm9.4Fe84.6-XCoXV6.0(X=0，10，20和30)合金在Ar气氛下感应熔炼，然后在1150℃下进行20h的均化处理。X射线衍射分析表明，该合金接近单相Sm3(Fe，Co，V)29，并含有少量的aFe(Co，V)。均化后的合金被粉碎成粉末，筛分到小于63μm的粒度，然后压制成绿色压坯。样品是在歧化反应的不同阶段，在氢气下加热到620-700℃之间，然后1小时后，在氢气中快速冷却得到的。歧化样品在真空下加热到590-750℃的温度，10min-12小时后，在真空下快速冷却，得到HDDR样品。然后将一些HDDR样品在560℃下氮化4小时，然后研磨成粉末，与在1.0mAm-1(12KoE)的磁场中固化的熔融石蜡混合。用振动样品磁强计(VSM)测量了样品的磁性能。结果：随着钴的加入，Sm9.4Fe84.6-XCoXV6.0(X=0，10，20，30)合金的歧化温度升高，复合温度降低。这表明，钴稳定了Sm3(Fe，Co，V)29相在氢中的歧化，并加快了复合成aFe(Co，V)和TbCu7型相的速度。用透射电子显微镜观察到直径约为5 nm的SmH2棒。在630℃下复合1h的30%Co样品中发现了尺寸为50-100 nm的颗粒。除了aFe(Co，V)和TbCu7型相外，X射线衍射仪还发现，渗氮后存在一个在高Co含量和低温下形成的未知相，这似乎对磁性能产生了不利的影响。较少