K. JESHURUN LIJAY
,
J. DAVID RAJA SELVAM
,
I. DINAHARAN
,
S. J. VIJAY
中国有色金属学报(英文版)
doi:10.1016/S1003-6326(16)64255-3
采用K2TiF6无机盐和SiC陶瓷颗粒与铝熔体原位反应制备不同含量TiC颗粒(0,2.5%,5%,质量分数)增强AA6061铝合金。为分解SiC释放碳原子，合金在高温下进行铸造，并保温一段时间。X射线衍射分析表明铝基复合材料中只生成TiC颗粒而未见其他金属间化合物。采用场发射扫描电子显微镜(FESEM)和背散射电子衍射(EBSD)分析AA6061/TiC复合材料的显微组织。结果表明原位生成的TiC颗粒分布均匀，界面清晰，结合良好，并具有立方、球形和六方等形状。EBSD图像表明TiC颗粒对复合材料具有明显的晶粒细化效果。TiC颗粒可提高铝基复合材料的显微硬度和抗拉强度。
关键词:
铝基复合材料
,
碳化钛
,
背散射电子衍射
,
铸造
,
显微组织
,
力学性能
Journal of Vacuum Science & Technology a-Vacuum Surfaces and Films
Chromium nitride (CrN) films were deposited on Si wafers by arc ion plating (AIP) at various negative bias voltages and several groups of N-2/Ar gas flux ratios and chamber gas pressures. The authors systematically investigated the influence of negative bias voltage on the synthesis, composition, microstructure, and properties of the AIP CrN films. In this part (Part I), the investigations were mainly focused on the macroparticle distributions and film-growth characteristics. The results showed that macroparticle densities on the film surfaces decreased greatly by applying negative bias voltage, which can be affected by partial pressure of N-2 and Ar gases. From the statistical analysis of the experimental results, they proposed a new hybrid mechanism of ion bombardment and electrical repulsion. Also, the growth of the AIP CrN films was greatly altered by applying negative bias voltage. By increasing the bias voltage, the film surfaces became much smoother and the films evolved from apparent columnar microstructures to an equiaxed microstructure. The impinging high-energy Cr ions accelerated by negative bias voltages were deemed the inherent reason for the evolution of growth characteristics. (c) 2008 American Vacuum Society.
关键词:
chromium nitride films;hybrid coating system;structure zone model;si-n coatings;mechanical-properties;tin films;thin-films;pulse bias;vacuum;evaporation
Acta Materialia
Cyclic deformation behavior of Cu-30% Zn single crystals oriented for single slip was studied at constant plastic shear strain amplitudes (gamma(pl)) in the range of 3.8 x 10(-5)-6.4 x 10(-3) in order to understand systematically the fundamental fatigue behavior of low stacking fault energy materials. Results indicate that the cyclic hardening behavior strongly depends on the strain amplitude applied. For low strain amplitudes (gamma(pl) <3 x 10(-4)), cyclic saturation occurred after an initial cyclic hardening stage, but for high strain amplitudes (gamma(pl) greater than or equal to 6.0 x 10(-4)) saturation could not be reached until fatigue failure. The initial cyclic hardening rate (theta(0.2)) was found to decrease with increase in the applied strain amplitude. Slip bands were found to behave very similarly to Luders band appearance at the beginning as well as in the middle stage of cyclic deformation. Particularly, the similarity of the cyclic hardening behavior at low and high strain amplitudes to the work hardening response in stages I and II of tensile deformation of the same alloy has been pointed out. Cyclic stress was further decomposed into two terms, the effective stress and the internal stress, and both were found to increase continuously with cyclic deformation. It has been demonstrated that the activities of secondary slips played an important role in the continuous cyclic hardening at high gamma(pl). A comparison of the present result with previous relevant work on both wavy and planar slip materials has been attempted. The transition of wavy slip mode to planar slip mode of Cu-Al and Cu-Zn alloys has been discussed in terms of the electron-atom ratio and the critical Value of the ratio for such a transition is found to be 1.18-1.19 for both alloys. (C) 1998 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights reserved.
关键词:
stress-strain response;dislocation-structures;alpha-brass;fatigue;alloys;cu-16;temperature;amplitude
新型炭材料
Electrochemical capacitors (ECs) store energy in eletric double-layers formed along the interface of electrode material and electrolyte, this produces an extremely large capacitance compared with the traditional capacitors. The fundamental principles of electrochemical capacitors are briefly introduced, and the key materials used like electrode materials, electrolytes, separator and current collector materials are summarized. Electrochemical capacitors with pseudocapacitance, such as metal oxides, polymers and hybrid capacitors, are also discussed. The characteristics, possible application fields, the development state, the future R&D prospects for electrochemical capacitors are highlighted.
关键词:
electrochemical capacitors;supercapacitors;storage of electric energy;principles
王猛
,
林鑫
,
苏云鹏
,
沈淑娟
,
黄卫东
金属学报
对亚包晶、过包晶以及接近包晶点分成的Zn-Cu二元合金进行了定向凝固实验, 研究其在45 K/mm的温度梯度以及2—6400 μm/s凝固速度下的组织选择及深化规律, 发现Zn-2%Cu的低速度凝固组织为η相单相生长, 高速下为η相胞晶+胞晶间ε相的组织; Zn-2.7%Cu, Zn-3%Cu以及Zn-4%Cu的低速凝固组织为η相基体+ε相定向枝晶, 高速凝固组织为η相胞晶+ε相等轴晶, 基于最高界面生长温度判据, 在充分形核假设下对凝固过程中的相选择规律进行了分析, 并与实验结果较好的吻合.
关键词:
Zn-Cu包晶合金
,
null
,
null
Physica Status Solidi B-Basic Research
Within the framework of the linear spin wave approximation, the quantum fluctuations of spins at zero temperature in four-sublattice ferrimagnetic systems are studied by employing retard Green's functions. The effects of exchange constants on the quantum fluctuations of spins are discussed for three different spin-configurations. The magnetic properties of these spin configurations are related to their magnetically structural symmetry. When the parameters of the exchange couplings are adjusted, the crossover of the spin configurations results in the strong quantum fluctuations, owing to the behaviors of the non-three-dimensional magnetically system. When two of the four exchange-constants in the present four-sublattice bulk systems are set to be zero, the system behaves as a non-three-dimensionally magnetic system, although the structure of the system is still three-dimensional. All the exchange couplings involve in the quantum competition of the systems, but the effects of antiferromagnetic and ferromagnetic exchange couplings are different evidently. The antiferromagnetic exchange couplings play an important role in a balance of the quantum competition.
关键词:
heisenberg-antiferromagnet;3-layer superlattices;magnetic-structures;phase-transition;internal energy;ferromagnet;lattice;magnetoresistance;3-sublattice;dependence
陈志永
,
才鸿年
,
常亚喆
,
张新明
,
刘楚明
金属学报
采用取向分布函数和取向线分析方法研究了初始自由分布和具有近似立方织构的多晶铝轧制织构的演变规律.结果表明: 随着轧制变形的进行, 对于初始自由分布的样品, 晶粒取向主要向α, β取向线附近聚集, 其形变织构主要由C, S及B织构组成, 且3种织构成分密度值相差不大; 对于初始具有近似立方织构的样品, 晶粒取向主要向β取向线上聚集, 其形变织构主要由C, S织构组成, B织构成分相对较弱. 2种情况下S织构成分体积分量均比C, B织构高.
关键词:
多晶铝
,
rolling deformation
,
initial texture
,
random distribution
