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Formation of non-equilibrium phases and associated structural transition in the Pd-ta system induced by ion beam mixing

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Science China(Technological Sciences) 2011年第3期54卷 676-681页

作者： ZHAO Man DAI Ye LI JiaHao LIU BaiXin Advanced Materials Laboratory Department of Materials Science and Engineering Tsinghua University Beijing 100084 China

For the Pd-ta system characterized by a negative heat of formation of -78 kJ/mol, 200 keV xenon ion beam mixing with nano-sized Pd-ta multilayered films was conducted to study the non-equilibrium phase formation. The results showed that uniform amorphous alloys can be formed within a composition range of 25 at%-78 at% ta, which falls in the maximum possible amorphization range of 22 at%-80 at% ta predicted by the empirical model. Moreover, two metastable crystalline phases both of FCC structure, yet with different lattice constants were obtained. Interestingly, a self-assembled fractal pattern was observed in the Pd52ta48 multilayered films after irradiation to a dose of 1×1015 Xe+/cm2 and its dimension was determined to be 1.75±0.05. The possible mechanisms for the formation of amorphous and metastable crystalline phases as well as for the growth of the fractal pattern were discussed.

关键词：面心立方结构非平衡相离子束混合系统 ta 诱发非晶合金

Hf和ta对镍基粉末高温合金蠕变断裂特征和性能的影响

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金属学报 2023年

作者：张浩鹏白佳铭李新宇李晓鲲贾建刘建涛张义文东北大学材料科学与工程学院钢铁研究总院高温材料研究所北京钢研高纳科技股份有限公司

通过SEM、TEM和EBSD等表征手段，从多尺度研究了在650～750℃范围内Hf和ta对镍基粉末高温合金蠕变断裂特征和性能的影响。结果表明，添加Hf和ta可以显著延长合金的蠕变断裂时间，降低最小蠕变速率，提高合金的承温能力和持久强度。各蠕... 详细信息

通过SEM、TEM和EBSD等表征手段，从多尺度研究了在650～750℃范围内Hf和ta对镍基粉末高温合金蠕变断裂特征和性能的影响。结果表明，添加Hf和ta可以显著延长合金的蠕变断裂时间，降低最小蠕变速率，提高合金的承温能力和持久强度。各蠕变温度下的断口形貌类型一致，裂纹源区均为沿晶断裂，裂纹扩展区均为混合断裂，但是Hf和ta的添加显著降低了裂纹源区的面积。由于合金的层错能随着温度的升高而增加，蠕变变形机制由650℃下的微孪晶剪切为主导转变为7 5 0℃下的微孪晶剪切和超点阵层错剪切共同主导。添加Hf和ta提高了合金中MC型碳化物的含量，显著降低了退火孪晶界的密度，有效抑制了二次裂纹的形核。添加Hf和ta细化了晶界上的M23C6相并使其不连续析出，强化了晶界，抑制了沿晶断裂。添加Hf和ta降低了合金在各温度下的层错能，提高了变形微孪晶的密度，增大了位错运动的阻力。添加Hf和ta增加了二次γ′相的体积分数和平均尺寸，增大了γ和γ′相的晶格错配度，增强了γ/γ′相界面的强化作用。

关键词：镍基粉末高温合金 Hf ta 蠕变断裂特征蠕变性能

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NbSn超导线材中ta层的去除及腐蚀机理

金属学报 2023年

作者：高瞻张泽荣程军胜王秋良中国科学院赣江创新研究院中国科学院电工研究所中国科学技术大学

为了探究Nb3Sn超导线材中ta阻挡层的去除方法，选取内锡法制备的Nb3Sn超导线材为实验对象，研究了线材在HF溶液、HF气氛、HF和H2O2的混合溶液以及HF和HNO3的混合溶液中的腐蚀行为和特征，利用SEM和OM分析了线材微观结构和腐蚀形貌。结... 详细信息

为了探究Nb3Sn超导线材中ta阻挡层的去除方法，选取内锡法制备的Nb3Sn超导线材为实验对象，研究了线材在HF溶液、HF气氛、HF和H2O2的混合溶液以及HF和HNO3的混合溶液中的腐蚀行为和特征，利用SEM和OM分析了线材微观结构和腐蚀形貌。结果表明，ta层在HF和HNO3的混合溶液中腐蚀最快，在HF和H2O2的混合溶液中次之，在HF气氛中较慢，在HF溶液中最慢。综合腐蚀后效果，采用HF和H2O2的混合溶液进行腐蚀是去除Nb3Sn超导线材中ta阻挡层的最佳方法。同时，选取高纯ta片为研究对象，分别在上述介质中进行腐蚀实验，并通过OM、XRD和XPS观察和分析试样腐蚀形貌、物相结构变化和腐蚀溶液中的元素价态，揭示了ta的腐蚀机理，氧化剂的存在可以通过加快ta表面ta2O5膜的形成来加快HF对ta的腐蚀速率。

关键词： Nb Sn超导线超导接头 ta HF腐蚀

Investigation on the Initial Stage of Film Growth in Situ

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Journal of Materials Science & Technology 1994年第6期10卷 451-454页

作者： Zhenzhong QI Guopin DU Hanqi KE and Weiguo YAO(Institute of Solid State Physics, Chinese Academy of Sciences, Hefei, 230031, China) Inst of Solid State Physics Hefei China

The initial stage of Ag film growth on Cu(100). ta(100) and ta(110) single crystals as well as YBaCuO on Si single crystal covered by Pd was investigated in situ by means of LAS 600 surface analysis system with a sputtering source in sample preparation chamber. The results show that the initial state for Ag / Cu(100) film growth is typical S-K model, for Ag / ta(100) and Ag / ta(110)they have the same S-K characteristics, but due to the different surface energies of two crystalline planes. there is some difference for Ag / ta (100) and Ag / ta(110). YBCO sputterjng process is rather complex and Cu is the first element appearing in the film.

关键词： ta Investigation on the Initial Stage of Film Growth in Situ Ag Cu

Classification of Special Anosov Endomorphisms of Nil-manifolds

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Acta Mathematica Sinica,English Series 2019年第12期35卷 1871-1890页

作者： Seyed Mohsen MOOSAVI Khosro taJBAKHSH Department of Mathematics Faculty of Mathematical Sciences Tarbiat Modares University

In this paper we give a classification of special endomorphisms of nil-manifolds:Let f:N/Γ→N/Γbe a covering map of a nil-manifold and denote by A:N/Γ→N/Γthe nil-endomorphism which is homotopic to f.If f is a spe... 详细信息

关键词： Hyperbolicity Anosov endomorphisms special Anosov endomorphisms ta maps nilmanifolds

Transmitarray and Reflectarray Antennas Based on a Magnetoelectric Dipole Antenna

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Electromagnetic Science 2023年第1期1卷 42-55页

作者： Kwai-Man Luk Bingjie Xiang City University of Hong Kong Hong Kong SAR999077China City University of Hong Kong Shenzhen Research Institute Shenzhen 518057China

This paper presents a review of transmitarray(ta)and reflectarray(RA)antennas based on the magnetoelectric(ME)dipole antenna struc-ture.First,the basic operating principles of ME dipole,ta and RA antennas are introduced.Next,ME-dipole-based ta and RA designs are discussed,with four antenna designs presented in detail,including two fixed-beam ta designs with high aperture efficiencies and two reconfigurable designs with a beam-scanning capability.The techniques involved in these designs are also analyzed to provide insight into the ME-dipole-based ta and RA designs.The simulated and measured results of the reported prototypes show that the introduction of the ME dipole antenna significantly broadens the band-widths of the ta and RA antennas not only in the fixed-beam designs but also in the reconfigurable designs.The ME-dipole-based ta and RA designs reported in this paper are compared to highlight their benefits and limitations.Future possible research directions and challenges are also discussed.

关键词： Beam scanning High aperture efficiency ME dipole RA ta Wideband

On the Formability of Some Metastable Alloy Phases

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Journal of Materials Science & Technology 1994年第1期10卷 23-26页

作者： Bo taNG Deshan KANG Pei QING Weiming ZHANG and Nianyi CHEN(Shanghai Institute of Metallurgy, Chinese Academy of Sciences, Shanghai, 200050, China) Shanghai Inst of Metallurgy Shanghai China

Pattern recognition and neural network methods have been used to investigate the formability of metastable alloy phases, It has been found that some chemi cal bond parameters Such as valence electron number, electronegativity and metallic radii of cor-nponent elements are the dominating fac tors affecting metastable alloy phase formation. Some semi-empirical rules found in this way may be useful for the construction of expert system for materials design.

关键词： Figure Cd Ni On the Formability of Some Metastable Alloy Phases Chen Pb Sn ta

Experimental study on the partition behaviour of ta, Nb and W between different phases in the processes of crystallization differentiation of albite granitic magma

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Chinese Science Bulletin 1997年第16期42卷 1372-1377页

作者： Zhao, JS Zhao, B Rao, B Chinese Acad Sci Guangzhou Inst Geochem Guangzhou 510640 Peoples R China Nanjing Univ Dept Earth Sci Nanjing 210008 Peoples R China

To counter the lack of consensus of opinion on mineralizations of ta, Nb and W which have genetic relationship to fluorine-rich albite granite and the want of experimental evidence at present, some experiments reported in this study were carried out. The purpose of this study is to explain the genetic connection of ta, Nb and W ore deposits and possible mechanism of their mineralization with the aid of the experimental results.

关键词： partition behaviour of ta Nb and W process of crystallization differentiation of magma.

The effect of Bi composition on the electrical properties of InP1-xBix

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Science China(Physics,Mechanics & Astronomy) 2017年第4期60卷 82-85页

作者： GuanNan Wei Xing Dai Qi Feng WenGang Luo YiYang Li Kai Wang LiYao Zhang WenWu Pan ShuMin Wang ShenYuan Yang KaiYou Wang State Key Laboratory of Superlattices and Microstructures Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China State Key Laboratory of Semiconductor Materials Science Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China State Key Laboratory of Functional Materials for lnformatics Shanghai Institute of Microsystem and Information TechnologyChinese Academy of SciencesShanghai 200050China

Ⅲ-ⅤSemiconductors containing a small amount of Bi,known as dilute bismides,have attracted great interest in recent years,due to the large band-gap reduction and other unique properties[1,2].Previous studies have been primarily focused on the growth and optical properties of the GaAs-based bismuthides[3],while the properties of other dilute bismides are less well understood.Berding et al.[4]theoretically predicted that InPBi is expected to be

关键词： In Bi ta The effect of Bi composition on the electrical properties of InP x)Bi_x