S.G. Tian
,
L.T. Zhang
,
H. M. Shao
,
L.J. Zou
,
T.F. Li
,
and H. C. Yang (Department of Materials Science
,
Shenyang Polytechnic University
,
Shenyang 110023
,
China) (Corrosion Science Laboratory
,
Institute of Corrosion and Protection of Metals
,
Chinese Academy ofSciences
,
Shenyang 110015
,
China) (Department of Materials Science
,
Northeastern University
,
Shenyang 110006
,
China)
金属学报(英文版)
In this paper, internal oxidation kinetics and the diffusion mechanism of oxygen in sintered Cu-Al alloy have been studied by means of scanning electron microscopy,transmission electron microscopy and heat-weighting scales. The results show that the kinetic curves obey the parabolic law in the initial stage and are linear in the late stage.The oxygen atoms are mainly transported in the from of grain boundary diffusion and volume diffusion in the process of internal oxidation. The plastic deformation of Cu matrix around oxide particles increases the probability of [O] atoms moving in accordance with dislocation diffusion mechanism. Meanwhile, the activation energy and diffusion coefficient in the process of internal oxidation are evaluated by means of kinetic method so as to obtain the velocity equations of reacting interface moving in different stage.
关键词:
: Cu-Al alloy
,
null
,
null
LIU Guoquan Department of Materials Science and Engineering
,
University of Science and Technology Beijing
,
100083
,
China.
材料科学技术（英文）
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
,
null
,
null
,
null
QIAO Lijie LIU Rui XIAO Jimei University of Science and Technology Beijing
,
Beijing
,
China
金属学报(英文版)
The effects of stress components on nucleation sites and propagation directions of stress cor- rosion cracks in brass were investigated with specimens under mode Ⅱ and mode Ⅲ loadings. The results indicated that under mode Ⅱ loading,stress corrosion cracks nucleated on the site with maximum normal stress component and propagated along the plane perpendieular to the maximum normal stress,under mode Ⅲ loading,the stress corrosion crack was not evident on the 45°plane due to the general corrosion in aqueous solution with high NH_4OH concentra- tion,while stress corroded in aqueous solution with low NH_4OH concentration, numerous cracks with spacings of 10—150μm were found on the 45°plane with maximum normal stress and no stress corrosion cracks was observed on the plane with maximum shear stress.
关键词:
stress corrosion cracking
,
null
,
null
,
null
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（英文）
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:
N.V.Ch
,
ra Shekar
,
P.Ch.Sahu
,
K.Govinda Rajan
材料科学技术（英文）
Laser-heated diamond-anvil cell (LHDAC) is emerging as the most suitable, economical and versatile tool for the measurement of a large spectrum of physical properties of materials under extreme pressure and temperature conditions. In this review, the recent developments in the instrumentation, pressure and temperature measurement techniques, results of experimental investigations from the literature were discussed. Also, the future scope of the technique in various avenues of science was explored.
关键词:
Laser heating
,
null
,
null
,
null
International Journal of Hydrogen Energy
A systematic investigation on the hydrogen storage properties of Li-Mg-N-H materials with various compositions was performed. Li-Mg-N-H hydrogen storage materials were prepared by mechanically milling LiNH2/MgH2 mixtures with initial molar ratios ranging from 1.5:1 to 3: 1, followed by de/rehydriding at 200 degrees C. It was found that the hydrogen storage capacity of the system was highly dependent on the initial phase ratio of the LiNH2/MgH2 mixture. An optimum hydrogen capacity of about 5 wt% was achieved in the 2.15:1 LiNH2/MgH2 mixture. Different carbon materials, such as the single-walled carbon nanotubes (SWNTs), multi-walled carbon nanotubes, graphite and activated carbon, were used as additive to improve the hydrogen storage performance. It was found that the dehydriding kinetics of the Li-Mg-N-H material could be markedly improved by adding a small amount of SWNTs, especially in the as-prepared state. (c) 2006 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.
关键词:
hydrogen storage;dehydriding kinetics;carbon nanotubes;arc-discharge method;system;microstructure;desorption;absorption;behaviors;property;imides
Materials Letters
Mechanical alloying (MA) of elemental powder mixtures of Fe50Nb35C15, Fe60Nb30C10 and Fe50Nb40C10 was performed using a high energy ball mill. In the MA processing, ball milling first leads to a Fe-Nb-C amorphous phase and nanocrystalline NbC. Further milling results in the formation of a nanocrystalline solid solution of Fe(Nb, C) and nanocrystalline NbC in Fe50Nb35C15 and Fe60Nb30C10, while the final product for Fe50Nb40C10 is a mixture of amorphous Fe-Nb-C and nanocrystalline NbC.
关键词:
mechanical alloying;Fe;Fe, Nb and C powders;amorphous;nanocrystalline;solid solution
