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Effects of crystallization fractions on mechanical properties of Zr-based metallic glass matrix composites

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Science china(physics,Mechanics & Astronomy) 2010年第3期53卷 424-429页

作者： QIU ShengBao1,2. YAO KeFu1 & GONG Pan1 1 KLAMPT, Department of Mechanical Engineering, Tsinghua University, beijing 100084, china 2.Institute of Industry Technology, Guangzhou &{2., Guangzhou 511458, china KLAMPT Department of Mechanical Engineering Tsinghua University Beijing China Institute of Industry Technology Guangzhou & Chinese Academy of Sciences Guangzhou China

The Zr41Ti14Cu12.5Ni10Be2..5 (at.%) bulk metallic glass composites with various crystallization fractions were prepared by pretreating the bulk metallic glassy samples with pulsing current, and then by isothermal annealing at near initial crystallization temperature for different periods of time. The precipitations and crystallization fractions were studied by X-ray diffraction (XRD) and differential scanning calorimetry (DSC), and their effects on mechanical properties of the composite were studied by microhardness, uniaxial compression test and scanning electron microscopy (SEM). The experimental results show that the primary precipitate is quasicrystalline phase and other metastable phases including Be2.r, Zr2.u and FCC would precipitate subsequently. In the initial crystallization process, in which the crystallization fraction increases from 0 to 8.2., both fracture strength and plastic strain increase, with the maximum plastic strain up to 6.4%. When the crystallization fraction is larger than 8.2., the fracture strength and the plastic strain decrease sharply. Furthermore, the alloy with low crystallization fraction is fractured by shearing, while for high crystallization fraction it is fractured by splitting and cleavage. The results show that the mechanical properties of the glassy alloy could be optimized by controlling the processing parameters.

关键词： bulk metallic glass pulsing current crystallization fraction plasticity shear band

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钴纳米粒子自组装有序阵列与磁性

物理学报 2003年第12期52卷 3114-3119页

作者：杨海涛申承民杜世萱苏轶坤王岩国汪裕萍高鸿钧中国科学院物理研究所纳米物理与器件实验室北京100080 中国科学院物理研究所电子显微镜实验室北京100080 北京大学电子显微镜实验室北京100871

采用高温液相分解法制备出平均粒径不同的单分散的钴纳米粒子 .用自组装的方法得到二维和三维的钴纳米粒子有序阵列 ,用透射电子显微镜研究了粒径、温度、有机溶剂以及浓度对钴纳米粒子的自组装的影响 .用超导量子干涉仪研究了钴纳米粒... 详细信息

采用高温液相分解法制备出平均粒径不同的单分散的钴纳米粒子 .用自组装的方法得到二维和三维的钴纳米粒子有序阵列 ,用透射电子显微镜研究了粒径、温度、有机溶剂以及浓度对钴纳米粒子的自组装的影响 .用超导量子干涉仪研究了钴纳米粒子的超顺磁性 .这些研究结果为深入研究磁性纳米粒子的物性和在纳米器件中的应用奠定了良好的基础 .

关键词：钴纳米粒子自组装高温液相分解法透射电子显微镜超导量子干涉仪超顺磁性纳米器件

某些类氖离子和类镍离子等离子体状态对应关系的研究

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物理学报 2003年第9期52卷 2200-2205页

作者：燕飞张杰鲁欣中国科学院物理研究所光物理重点实验室北京100080

利用一维拉格朗日流体动力学程序Med10 3详细研究了产生类镍Ag ,Cd ,In ,Sn,Sb离子和类氖Fe ,Co ,Ni,Cu,Zn离子的等离子体状态 .通过对电子温度、离子丰度、离子数密度等状态参量的分析比较 ,得到了这两类等离子体状态之间的对应关系 .... 详细信息

利用一维拉格朗日流体动力学程序Med10 3详细研究了产生类镍Ag ,Cd ,In ,Sn,Sb离子和类氖Fe ,Co ,Ni,Cu,Zn离子的等离子体状态 .通过对电子温度、离子丰度、离子数密度等状态参量的分析比较 ,得到了这两类等离子体状态之间的对应关系 .即类镍银的等离子体状态与类氖铁的相近 ,类镍镉的与类氖钴的相近 ,依次类推 .

关键词：类氖离子类镍离子等离子体状态对应关系 X射线激光一维拉格朗日流体动力学程序等离子体诊断

Build Axial Gradient Field by Using Axial Magnetized Permanent Rings

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Journal of Materials Science & Technology 2002年第6期18卷 483-484页

作者： Quanling PENGInstitute of High Energy physics, chinese academy of sciences P.O. Box 918-9, {2. 100039, china chinese Acad Sci Inst High Energy Phys Beijing 100039 Peoples R China

Axial magnetic field produced by an axial magnetized permanent ring was studied. For two permanent rings, if they are magnetized in the same directions, a nearly uniform axial field can be produced. If they are magnetized in opposite direction, an axial gradient magnetic field can be generated, with the field range changing from-Bo to Bo- A permanent magnet with a high axial gradient field was fabricated, the measured results agree with the PANDIRA calculation very well. For wider usage, it is desirable for the field gradient to be changed. Some methods to produce the variable gradient field are presented. These kinds of axial gradient magnetic field can also be used as a beam focusing for linear accelerator if the periodic field can be produced along the beam trajectory. The axial magnetic field is something like a solenoid, large stray field will leak to the outside environment if no method is taken to control them. In this paper, one method is illustrated to shield off the outside leakage field.

关键词： Axial magnetized permanent ring electron beam Leakage

Characterization of different-Al-content AlGaN/GaN heterostructures on sapphire

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Science china(physics,Mechanics & Astronomy) 2010年第1期53卷 49-53页

作者： DING GuoJian , GUO LiWei, XING ZhiGang, CHEN Yao, XU PeiQiang, JIA HaiQiang, ZHOU JunMing & CHEN Hong beijing National laboratory of Condensed Matter {2., Institute of {2., chinese academy of sciences, beijing 100190, china beijing National laboratory of Condensed Matter {2. Institute of Physics Chinese Academy of Sciences Beijing China

Al x Ga 1-x N/GaN high-electron-mobility transistor (HEMT) structures with Al composition ranging from x = 0.13 to 0.36 are grown on sapphire substrates by low-pressure metalorganic chemical vapor deposition (LP-MOCVD). The effects of Al content on crystal quality, surface morphology, optical and electrical characteristics of the AlGaN/GaN heterostructures have been analyzed. Although high Al-content (36%) heterostructure exhibits a distinguished photoluminescence peak related to recombination between the two-dimensional electron gas and photoexcited holes (2.EG-h), its crystal quality and rough surface morphology are poor. 2.EG mobility increases with the Al content up to 2.% and then it apparently decreases for high Al-content (36%) AlGaN/GaN heterostructure. The increase of sheet carrier density with the increase of Al content has been observed. A high mobility at room temperature of 2.05 cm 2./V s with a sheet carrier density of n s = 1.10 × 10 13 cm -2., for a 2.% Al-content AlGaN/GaN heterostructure has been obtained, which is approaching state-of-the-art for HEMT grown on SiC. Sheet resistance as low as 2.4 Ω/□ has also been achieved.

关键词： AlGaN Hall-effect luminescence

Adsorption and reaction of CO and O_2.on the Ag/Pt(110) surface studied by photoemis-sion electron microscopy

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chinese Science Bulletin 2001年第12期46卷 998-1002页

作者： HUANG Weixin & BAO XinheState Key laboratory of Catalysis, Dalian Institute of Chemical physics,{2., Dalian 11602., china State Key laboratory of Catalysis Dalian Institute of Chemical Physics Chinese Academy of Sciences Dalian China

The Ag/Pt(110) model catalyst was prepared by evaporating silver on Pt(110). Adsorption and reaction of CO and O2.on Ag/Pt(110) surface were studied in situ by photo-emission electron microscopy (PEEM) during the pressure range of 10-5-10-2.Pa at 480 K. The Ag/Pt(110) surface consisted of Pt(110), AgPt interface and Ag area after annealing at 500 K. The dosing pressure of CO and O2.had a larger influence on their adsorption on the Ag area than on the Pt(110) and AgPt interface. Small Pt clusters formed on the Ag area and AgPt interface, which had a stronger ability to adsorb CO than Pt(110) terrace. The existence of Ag had an obvious influence on the kinetic of CO oxidation on Pt(110). No pattern was observed on the AgPt interface under the same condition when the formation of reaction-diffusion waves occurred on Pt(110).

关键词： silver Pt(110) carbon monoxide oxygen adsorption reaction photoemission electron microscopy.

The X-ray emission from the knots in 3C 12.

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Science china(physics,Mechanics & Astronomy) 2010年第S1期53卷 212-215页

作者： ZHANG Jin1,2.3 & LI ShaoKun1,3 1 National Astronomical Observatories/Yunnan Observatory,chinese academy of {2.,Kunming 650011,china 2.College of physics and electronic Engineering,Guangxi Teachers Education University,Nanning 53002.,china 3 Graduate University of the chinese academy of sciences,beijing 100049,china National Astronomical Observatories/Yunnan Observatory Chinese Academy of Sciences Kunming China College of physics and electronic Engineering Guangxi Teachers Education University Nanning China Graduate University of the chinese academy of sciences Beijing China

3C 12. is a Seyfert galaxy with a well detected X-ray *** investigate the X-ray emission of its five jet knots and fit their spectral energy distributions(SEDs) from the radio to the X-ray bands with a single-zone lepton *** find that the SEDs of knots k7,s2.and s3 can be explained by synchrotron radiation,and the X-rays are the simple extension of the radio-optical emission component,but that of the inner knot k4 requires the IC/CMB model,in which the X-rays are due to the inverse Compton scattering of the cosmic microwave background photons by relativistic electrons in the jet with a beaming factor δ-*** outer knot k2. is resolved into a three-part *** is shown that the fitting of the X-rays from this knot with the IC/CMB model needs an extraordinary beaming factor δ-15-2. for a jet at the kpc *** the X-rays of knot k2. are produced by synchrotron radiation similar to k7,s2.and s3,they may be contributed by a relativistic electron population whose radiations in other wavelengths are not detected.

关键词： 3C 12. knots X-rays non-thermal emission

Deprojection technique for galaxy cluster considering the point spread function

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Science china(physics,Mechanics & Astronomy) 2010年第S1期53卷 183-186页

作者： WANG YuSa,JIA ShuMei & CHEN Yong Key laboratory for Particle Astrophysics,Institute of High Energy physics,chinese academy of sciences,beijing 100049,china Key laboratory for Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing China

We present a new method for the analysis of Abell 1835 observed by *** method is a combination of the Direct Demodulation technique and *** eliminate the effects of the point spread function(PSF) with the Direct Demodulation *** then use a traditional deprojection technique to study the properties of Abell *** to only using a deprojection method,the central electron density derived from this method increases by 30%,while the temperature profile is similar.

关键词： PSF Direct Demodulation deprojection Abell 1835 galaxy cluster XMM-Newton

Growth of Carbon Encapsulated Long Nickel Nanorods on Bulk Nickel Substrate

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Journal of Wuhan University of Technology(Materials Science) 2011年第1期26卷 28-32页

作者：宾晓蓓 College of Resources & Environment Engineering Wuhan University of Technology

Carbon nanotube encapsulated nickel nanorods were catalytic grown via pyrolysis of oil on a bulk nickel wire substrate. X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy and Raman spectroscopy were employed to characterize the as-prepared sample. The results show that, carbon nanotubes possess several microns in length, the filled metallic nickel nanorods with a uniform diameter of 35 nm were tightly encapsulated by the carbon capsules. The detailed formation mechanism for the carbon nanotubes encapsulated nickel nanorods were discussed briefly.

关键词： carbon nanotube nickel nanorod pyrolysis core-shell