C.X.Dong
,
X.Y.Luand B.B.Wei(Laboratory of Materials Sciencein Space
,
Northwestern Polytechnical University
,
Xi'an 710072
,
China)
金属学报(英文版)
The Ag-Ge eutectic alloy system was intensively investigated with respect to its solidification characteristics at large undercoolings which were obtained by the B2O3 glass fluxing technique combined with argon protection. Grain size refinement was found in the Ag-15 wt% Ge hypoeuteciic alloy. With inereasing undercoolings the feather-like structure disappeared in the Ag-19wt% Ge eutectic alloy, and even silver slips showed up at sufficient undercoolings. Nevertheless, the fact that germanium had nucleated in preference to silver was indicated by a fine germanium line in the middle of the silver slips. The various morphologies of the germanium phase in the Ag-25 wt% Gehypereutectic alloy including the five-fold symmetry structure were explained by the joint action of high undercoolings (i.e. growth velocities) and density differences. The corpled zone of this alloy system was qualitatively estimated.
关键词:
Ag-Ge alloys
,
null
,
null
,
null
WANG Fuhui Institute of Corrosion and Protection of Metals
,
Academia Sinica
,
Shenyang
,
ChinaBIAN Weimin Northeast University of Technology
,
Shenyang
,
China Institute of Corrosion and Protection of Metals
,
Academia Sinica
,
Shenyang
,
China
金属学报(英文版)
The space group of PrCo_(12)B_6,compound has been determined using the convergent beam elec- tron diffraction method.The space group is found to be R3m.
关键词:
convergent beam electron diffraction
,
null
,
null
Ieee Transactions on Magnetics
The spin orientation and spontaneous magnetostriction of multicomponent TbxDy1-x-yPry(Fe0.9B0.1)(1.93) (0.10 less than or equal to x less than or equal to 0.25, 0.30 less than or equal to y less than or equal to 0.60) Laves phases were studied by step-scanning their (440) X-ray diffraction lines. The easy magnetization direction (EMD) of the Laves phases changed from the (100) to (111) axis when x was increased from 0.10 to 0.25. With increasing y, the EMD of Tb0.15Dy0.85-yPry(Fe0.9B0.1)(1.93) and Tb0.2Dy0.8-yPry(Fe0.9B0.1)(1.93) Laves phases reoriented from the (100) to (111) axis. The magnetostriction coefficient lambda(111) of TbxDy1-x-yPry(Fe0.9B0.1)(1.93) Laves phases increased with increasing x (or y) when y (or x) was kept constant.
关键词:
Laves phases;magnetostriction;spin orientation;X-ray diffraction;anisotropy compensation;alloys
庄厚龙
,
彭平
,
周惦武
,
刘金水
稀有金属材料与工程
采用第一原理赝势平面波方法--CASTEP程序计算了4种B2型Y基金属间化合物YX(X=Ag,Cu,In,Rh)的部分弹性性质,计算结果与文献报道值基本一致.通过Pugh定律、Cauchy压力和泊松比等经验判据,分析并预测了它们的脆性/延性,其延性高低次序为:YRh＞YAg＞YCu＞YIn.电子结构分析表明:这4种金属间化合物良好的延性源于其较强的金属键,而不同程度的Y(d)-X(p)电子杂化则导致了其延性的差异.YIn中因In的p电子较多,杂化程度高,共价键方向性强,因而延展性最低,而YRh则由于存在Y(d)-Rh(d)电子间强的相互作用,增强了其金属键作用,因而延性最好.
关键词:
Y基金属间化合物
,
脆性/延性
,
第一原理
,
电子结构
陈慧余
,
张道元
,
王昌燧
,
卢国荣
,
兰志刚
金属学报
用X射线衍射、吸收和内转换电子发射Mossbauer谱技术,研究了Fe_(80-x)Cu_xSi_5B_(15)和(Fe_(1-y)Co_y)_(82)Cu_(0.4)Si_(4.4)B_(13.2)两系列非晶合金的晶化行为.单辊急冷法制备的非晶带,晶化首先从贴辊面开始,晶化产物为α-Fe相.在Fe_(80)Si_5B_(15)非晶合金中以少量Cu替代Fe可以提高晶化温度.我们的结果表明,过渡金属的含量超过80at.-％,如增加到82at.-％,晶化温度就明显降低.所研究两系列含Si的铁基非晶合金在400—450℃范围内退火2h,都出现α-Fe,Fe_3B和Fe_2B三种晶态相共存状态.退火温度再升高,亚稳相Fe_3B逐渐转变为Fe_2B和α-Fe.
关键词:
晶化
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amorphous alloy
,
crystalline phase
,
coexistence
Journal of Alloys and Compounds
The subsolidus phase relations of the system Y(2)O(3) -CaO-B(2)O(3) are investigated by means of X-ray diffraction (XRD) analyses. There are six binary compounds and three ternary compounds in this system. The phase diagram comprises 13 three-phase regions. The ternary compound CaYBO(4) is refined from powder XRD data by the Rietveld method. It has a warwickite-like structure with cell parameters a=10.4354(3) Angstrom, b=9.6126(2) Angstrom, c=3.5880(1) Angstrom and space group Nam. The rationality of the CaYBO(4) structure is examined by Brown bond valence model and IR spectra. (C) 2001 Elsevier Science BY. All rights reserved.
关键词:
oxide materials;crystal structure;X-ray diffraction;phase diagram;crystal-structure
张志纯
,
龙志林
,
危洪清
,
李乡安
,
彭建
,
唐平
稀有金属材料与工程
采用单辊法和铜模铸造法制备了Fe75-xMxHf3Y2B20(M=Co,Nb;x=0,4 at%)合金系的非晶薄带和非晶棒样品,并测试了该非晶合金系的差示扫描量热曲线、X射线衍射图谱和软磁性能.结果表明:少量的Nb或Co替代Fe75Hf3Y2B20中的Fe元素,合金的热稳定性和玻璃形成能力可得到明显的提高;其中Fe71Nb4Hf3Y2820的过冷液相区宽度△Tx高达75 K,约化玻璃转变温度Trg为0.58,直径达4 mm,饱和磁感应强度为0.97～1.08 T,该非晶合金同时具有较大的热稳定性、较强的玻璃形成能力和较好的软磁性能.
关键词:
铁基块体非晶合金
,
过冷液相区
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玻璃形成能力
,
软磁性能
Journal of Applied Physics
Y2Fe14B0.5C0.5 has the same tetragonal structure as Y2Fe14B with space group P4(2)/mnm. Magnetic properties of the Y2Fe14B0.5C0.5 compound have been studied using an extraction magnetometer with a maximum field of 6 T, in the temperature range from 1.5 to 300 K. By means of fitting the hard magnetization curves, the magnetocrystalline anisotropy constants K1, K2, and K3 were determined. It was found that although the magnetocrystalline anisotropy field (mu-0H-a) increases abnormally with increasing temperature as in the case of Y2Fe14B, the dependence of anisotropy constants on temperature is quite different from that of Y2Fe14B. K1 and K3 decrease slightly with increasing temperature. K2 increases abnormally with increasing temperature, which contributes to the abnormal dependence of anisotropy field on temperature. In addition, the substitution of carbon for boron leads to a reduction of 3d-3d interaction and spontaneous magnetization. In contrast, uniaxial anisotropy is increased by the addition of carbon below room temperature.
关键词:
alloys
Lizhi CHENG
,
Wei FENG
,
Xinquan DONG
,
Kuichang BAI and Kaiyuan HE (Dept. of Materials Science and Engineering
,
Northeastern University Shenyang 110006
,
China)
材料科学技术（英文）
The formation of nonequilibrium phase by mechanical alloying (MA) of Fe and B powders in a high energy vibration ball mill has been made for Fe100-xBx system with x=15. 30, 35, 45,55 and 70. By using the X-ray diffraction, magnetic measurement and M6ssbauer spectrummethods, it was revealed that the structure of the MA product varies with milling time and B contents.
关键词:
