Solid State Communications
Quantum coherence effect on the conductance scaling law G similar to L(-theta) of a fractal nonbranching Koch curve is addressed. The quantum conductivity exponent theta of the fractal is exactly solved by combining the Landauer formula with a renormalization decimation transformation.
关键词:
F.H. Froes(IMAP
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University of Idaho
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Moscow
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ID 838443026
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USA Manuscript received 26 August 1996)
金属学报(英文版)
The synthesis, processing and mechanical properties of the light metals, aluminum,magnesium and titanium Produced by advanced techniques are reviewed. Synthesis techniques to be addressed will include rapid solidification, spray deposition, mechanical alloying, plasma Processing and vapor deposition.
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:synthesis/processing
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Zhihua LIU
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Qing ZHAO
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Deqing LI
材料科学技术（英文）
In this paper, technology margin experiment of hollow cathode fusion are welding (FAW) and penetrating are welding (PAW) is presented in detail. The advantages of PAW, compared with FAW, are better weld formation, narrower welds, as well as a larger welding technology margin. Technological experiment and hydraulic test for the Ti alloy pressure vessels with PAW are described. Also, the weld formation control on Ti alloys is preliminarily analyzed. Finally, conclusions are addressed.
关键词:
Ke LU
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Jian LU
材料科学技术（英文）
In this paper, a concept of surface nanocrystallization (SNC) of metallic materials is introduced. Three types of SNC processes are classified. Different SNC mechanisms and possible techniques for SNC are discussed with emphasis on mechanically induced surface self-nanocrystallization. Further development and prospects are addressed with respect to the properties and behaviors of the materials with a nanocrystalline surface. Enhancement of the behavior of the engineering materials by means of the SNC technology and its industrial application possibilities are analyzed.
关键词:
Z.L.Wang
材料科学技术（英文）
Property characterization of nanomaterials is challenged by the small size of the structure because of the difficulties in manipulation. Here we demonstrate a novel approach that allows a direct measurement of the mechanical properties of individual nanotube-like structures by in-situ transmission electron microscopy (TEM). The technique is powerful in a way that it can directly correlate the atomic-scale microstructure of the carbon nanotube with its physical properties, providing a one-to-one correspondence in structure-property characterization. Applications of the technique will be demonstrated on mechanical properties, the electron field emission and the ballistic quantum conductance in individual nanotubes.
关键词:
J.X Luo and Y.X. Tan (State Key Lab. for Mechanical Behavior of Materials Xi′an Jiaotong University
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Xi'an 710049
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China Manuscript received 29 September 1995)
金属学报(英文版)
The relationships between fatigue threshold △Kth and the initial yield .strength σ0 of normalized 1035 steel after various prestrain (at fist, second and third hardening stages respectively) were investigated through the analysis of theσ-εcurves and transmission electron microscope (TEM). After prestraining at first or second hardening stage, there is a marked drop in the values of △Kth and σ0. This is in correspondence with the depinning of the solute atoms from the dislocation lines in the Cottrell atmosphere.At the third hardening stage of prestrain the fatigue threshold increases rapidly and △Kth is even 1.6 times as large as the original value. This is because at this stage no dislocation-cell free areas can be found and the refinement of the dislocation cells occurs with the increase in the prestrain level.
关键词:
:deformation hardening
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Materials Science and Engineering a-Structural Materials Properties Microstructure and Processing
A quantitative analysis of the fracture surface of a 1045 steel was undertaken in order to relate important microstructural features to brittle intergranular fractures in the steel. It was found that the character of the profile was not random but periodic. There is a direct correspondence between the Fourier spectrum of the profile and the microstructure features. Utilization of secondary-electron line scanning facilitated the analysis of the fracture surface in this case. The results of the analysis from both the profile and the scanning line showed that the first autocorrelation length is related to the average grain size and that the total power corresponds to the impact energy of the fracture.
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