MJ.Kim
,
Y.B.Kim
,
C.B.Song
,
Y.Li
,
D.S.Suhr
,
C.O.Kim
,
T.K.Kim
材料科学技术（英文）
The magnetic properties and microstructure of diffusion annealed [Ta/Nd/NdFeB/Nd/Ta] thin films have been investigated. The films were deposited on Si substrate with various thickness ratio of Nd/NdFeB layer (R=0 similar to 3.3), then diffused and crystallized by annealing at 650 degrees C for 10 min. The film without Nd layer showed soft magnetic behavior and high content of alpha-Fe phase. The films with R greater than or equal to 1 showed good hard magnetic properties with the high coercivity of about 20 kOe.
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Journal of Alloys and Compounds
Nd-Fe-(B.C) alloys have been synthesized by mechanical alloying and subsequent heat-treatment, with B4C as one of the starting materials. It is found that when the pure B4C is milled alone, it proves difficult to decompose. When the B4C compound is milled with Nd and Fe, the complete decomposition of B4C and the formation of Nd2Fe14(B,C) phase is observed. Furthermore, the competition between B and C atoms for entering the Nd2Fe14B lattice. the effects of the B4C content on the structure and the magnetic properties of Nd2Fe14(B,C)-based alloys are investigated. A coercivity as high as 18.3 kOe and the maximum energy product of 10.4 MGOe have been achieved for the Nd-Fe-(B,C) alloys. (c) 2005 Elsevier B.V. All rights reserved.
关键词:
permanent magnets;mechanical alloying;fe-c alloys;permanent-magnets;r2fe14c;nd
刘建功
,
殷小玮
,
成来飞
,
张立同
,
王琴
复合材料学报
为了降低液硅渗透法制备C／C—SiC复合材料中残留Si的含量，采用浆料浸渗结合液硅渗透工艺制备B12（C，Si，B）3改性C／C—SiC复合材料。通过分析不同比例B4C—Si体系在不同温度的反应产物，确定了B12（C，Si，B）3的生成条件。结果表明：B4C和Si在1300℃开始反应，生成少量B12（C，Si，B）3和SiC，且B12（C，Si，B）3的生成量随反应温度的升高而增加；当B4C和Si的摩尔比为3：1、反应温度为1500℃时，产物为B12（C，Si，B）3和SiC液硅渗透法制备的C／C—SiC复合材料相组成为非晶态C、β-SiC和B12（C，Si，B）3，未见残留Si。
关键词:
复合材料
,
C
,
C—SiC
,
B12(C，Si，B)3
,
浆料浸渗
,
液硅渗透
Physics Letters A
The magnetic properties of the mixed ferro-ferrimagnetic compounds with (A(a)B(b)C(c))(y)D, in which A, B, C and D are four different magnetic ions and form four different sublattices, are studied by using the Ising model. And the Ising model was dealt with standard mean-field approximation. The regions of concentration in which two compensation points or one compensation point exit are given in c-a, b-c and a-b planes. The phase diagrams of the transition temperature T-c and compensation temperature T-comp are obtained. The temperature dependences of the magnetization are also investigated. Some of the result can be used to explain the experimental work of the molecule-based ferro-ferrimagnet ((NiaMnbFecII)-Mn-II-Fe-II)(1.5) [Cr-III (CN)6] - zH(2)O. (C) 2003 Elsevier B.V. All rights reserved.
关键词:
mixed ferro-ferrimagnet;Ising model;four sublattices;phase diagram;transition temperature;compensation temperature;magnetic-properties;prussian blue;alloy
Journal of Alloys and Compounds
A model for diffusion is applied to the Ni-Al system to optimize the mobility parameters for the 132-b.c.c. phase by fitting the experimentally obtained diffusivities. In the model, the activation energy for diffusion is expressed as a function of the degree of ordering which is evaluated from thermodynamic data. The diffusivities, from the model are used to simulate diffusion experiments. The results are compared with experimental data and it is concluded that the model can yield satisfactory prediction. (C) 2007 Elsevier B.V. All rights reserved.
关键词:
intermetallics;diffusion;thermodynamic modeling;alloys;fe;interdiffusion;model
刘立强
,
陈蕴博
功能材料
设计了多种B4C结构模型,并对模型进行了结构优化,计算了各模型结构的单点能.结果表明,B4C的稳定结构为CBC(B11C),即它由C-B-C三原子链和B11C二十面体组成,B11C中C原子为极地占位.由于双极地占位的B10C2+B12结构能量与B11C结构相差较小,在通常材料制备条件下,B4C晶体中有少量B10C2+B12结构的存在是可能的.计算结果表明,B11C中极地C原子占位分布为有序化时能量较低,当B4C晶体在能量最低的平衡态时C原子在B11C二十面体中的占位应有一定的有序性.
关键词:
B4C
,
晶体结构
,
原子占位
,
单点能
,
稳定性
苏国跃
,
夏非
,
闻立时
金属学报
<正> SiC～Al_C_5-BC三元系在1800℃下除了生成Al_4SiC_4和Al_4Si_2C_5以外,还析出新的B-C-Al化合物,即Al_8B_4C_7相. 本文研究了Al_8B_4C_7相的存在范围,及其在不同温度和压力下对热压SiC烧结的影响. 实验采用工业SiC粉.试样在高于1800℃热
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