Z. Zhou
,
Q.S. Gan and P.D. Ding College of Materials Science and Engineering
,
Chongqing University
,
Chongqing 400044
,
China
金属学报(英文版)
The reduction of the volumes of the silica glass during aluminum reactive penetration was observed experimentally. The liquid aluminum infiltrates easily into the cavities while the released silicon solves in the liquid aluminum, and Al/A1_2 O_3 composites could be obtained finally. The experimental result has shown that Al/A1_2 O_3 composites could transform into A1_2O_3 grains by oxygen in the cavities of Al/A1_2O_3 composites during longer penetration treatment. The formation of alumina is a sintering process, in which liquid aluminum, particulate alumina and oxygen play an important role. Tin nsformed process has shown that there is a relationship of σAl_2O_3
关键词:
aluminum
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null
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null
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null
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null
Andrej Atrens
材料科学技术（英）
Corrosion research by Atrens and co-workers has made significant contributions to the understanding of the service performance of engineering materials. This includes: (1) elucidated corrosion mechanisms of Mg alloys, stainless steels and Cu alloys, (2) developed an improved understanding of passivity in stainless steels and binary alloys such as Fe-Cr, Ni-Cr, Co-Cr, Fe-Ti, and Fe-Si, (3) developed an improved understanding of the melt spinning of Cu alloys, and (4) elucidated mechanisms of environment assisted fracture (EAF) of steels and Zr alloys. This paper summarises contributions in the following: (1) intergranular stress corrosion cracking of pipeline steels, (2) atmospheric corrosion and patination of Cu, (3) corrosion of Mg alloys, and (4) transgranular stress corrosion cracking of rock bolts.
关键词:
Stress corrosion cracking
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null
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null
LIU Guoquan Department of Materials Science and Engineering
,
University of Science and Technology Beijing
,
100083
,
China.
材料科学技术（英）
Quantitative analysis of populations having a geometric structure,which has developed into a special scientific subject called microstructology or stereology,is of great importance to the characterization and evaluation of microstructures and their evolution in various processes.This paper, besides a brief discussion on those topics such as the recent developments of computer assisted image analysis,mathematical morphology,and fractal analysis,will mainly focus on the scope,fundamen- tals,present status,and perspectives of classical stereology.Several case examples of its application to materials science will also be given.
关键词:
stereology
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null
,
null
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null
Materials Science & Engineering C-Biomimetic Materials Sensors and Systems
Bamboo, one of the strongest natural structural composite materials, has many distinguishing features. It has been found that its reinforcement unit, hollow, multilayered and spirally-wound bast fiber, plays an extremely important role in its mechanical behavior. In the present work, on the basis of the study on bamboo bast fiber and wood tracheid, a biomimetic model of the reinforcing element, composed of two layers of helically wound fiber, was suggested. To detect the structural characteristics of such a microstructure, four types of macro fiber specimens made of engineering composites were employed: axially aligned solid and hollow cylinders, and single- and double-helical hollow cylinders. These specimens were subjected to several possible loadings, and the experimental results reveal that only the double-helical structural unit possesses the optimum comprehensive mechanical properties. An interlaminar transition zone model imitating bamboo bast fiber was proposed and was verified by engineering composite materials. In our work, the transition zone can increase the interlaminar shear strength of the composite materials by about 15%. These biomimetic structural models can be applied in the design and manufacture of engineering composite materials.
关键词:
bamboo;bast fiber;biomimetics;engineering composites
Science
Strengthening materials traditionally involves the controlled creation of internal defects and boundaries so as to obstruct dislocation motion. Such strategies invariably compromise ductility, the ability of the material to deform, stretch, or change shape permanently without breaking. Here, we outline an approach to optimize strength and ductility by identifying three essential structural characteristics for boundaries: coherency with surrounding matrix, thermal and mechanical stability, and smallest feature size finer than 100 nanometers. We assess current understanding of strengthening and propose a methodology for engineering coherent, nanoscale internal boundaries, specifically those involving nanoscale twin boundaries. Additionally, we discuss perspectives on strengthening and preserving ductility, along with potential applications for improving failure tolerance, electrical conductivity, and resistance to electromigration.
关键词:
strain-rate sensitivity;stacking-fault energy;nano-scale twins;cu-al;alloys;nanocrystalline metals;mechanical-properties;activation;volume;copper;deformation;behavior
吴历斌
,
黄富强
,
江莞
无机材料学报
doi:10.3724/SP.J.1077.2009.00427
利用结构功能区思想的导电功能区和透光功能区,提出了层状p型Cu/Q透明导体的设计模型. LaCuOTe和Sr3Cu2Sc2O5S2因结构层[Cu2Te2]和[Cu2S2]对应导电功能区、[La2O2]和[Sr3Sc2O5]对应透光功能区,符合模型设计思想,是兼具高导电性和高透光性的透明导体,光谱和电导等验证了模型设计p型透明导体的可行性和正确性. 从功能区角度,改变LaCuOS中导电功能层([Cu2S2]→[Cu2Te2])可显著提高材料导电性(10-3S/cm→100S/cm);替换LaCuOTe中透光功能层([La2O2]→[Sr3Sc2O5])能可控改善材料透光性(2.3eV→3.1eV).
关键词:
p型Cu/Q
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透明导体
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导电率
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层状结构
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结构功能区
Douxing LI and Hengqiang YE (Laboratory of Atomic imaging of Solids
,
Institute of Metal Research
,
Chinese Academy of Sciences
,
Shenyang
,
110015
,
China)
材料科学技术（英）
The present paper summarizes the current status of high resolution electron microscopy (HREM)and the applications of HREM to materials science and condensed matter physics. This review recounts the latest development of high resolution electron microscope, progress of HREM and the applications of HREM, including the crystal structure determination of microcrystalline materials and characterization of the local structure of the defects and nanostructured materials as well as qualitative and quantitative analysis of the grain boundaries, interfaces and interfacial reactions in the advanced materials by means of HREM in combination with electron diffraction,subnanometer level analysis, image simulation and image processing.
关键词:
Crystal Research and Technology
In this work, P-doped GaN nanowires were synthesized in a co-deposition CVD process and the effects of P-doping on the microstructure and cathodoluminescence (CL) of GaN nanowires were studied in details. SEM observation and CL measurments demonstrated that P-doping has led to a rough morphology evolution and a depression of the band-gap emission of GaN nanowires, whereas the visible emission of GaN nanowires was obviously enhanced. Finally, the corresponding morphology transition and optical properties of GaN nanowires with P-doping were discussed. (C) 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
关键词:
GaN;nanowires;nitride nanotubes;field-emission;growth;tunability;mechanism;si
