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
ZHAO Hongzhuang
,
Seokjae LEE
,
Youngkook LEE
,
LIU Xianghua
,
WANG Guodong
钢铁研究学报(英文版)
This study aims at the experimental analysis of the transformation induced plasticity (TRIP) phenomenon. Experiments are conducted in which martensite is allowed to grow under the influence of a series of externally applied stresses. The magnitude of the applied stresses is less than 67% of the yield strength of austenite σγ(Ts). Since there is no obvious difference between the transformation plasticity under tension and the compression for the lower applied stresses, only compressive stresses are applied. The results confirm that the transformation plasticity is proportional to the applied stress if the latter does not exceed 67% of σγ(Ts). The TRIPstrain, the kinetics, and their dependence on the applied stresses are studied. The comparison between calculated results and experimental results shows that the model accurately describes the phenomenon.
关键词:
applied stress;TRIP;martensite transformation;lowalloy steel
Materials & Design
It was found in a commercial single crystal superalloy CMSX-4 that preferential orientation of the gamma' rafting in dendrite core was not dependent on the sign of the applied stress sigma(A), but on the sign of the sum of the applied stress sigma(A) and a critical equivalent stress sigma(c). This critical equivalent stress sigma(c) caused by material inhomogeneity has been predicted previously; however it was first determined experimentally to be in the range 39.8-47.2 MPa in the present study. Moreover, it qualitatively demonstrated that the critical equivalent stress sigma(c) played a significant role in the creep behavior of superalloys at high temperature and low stress. (C) 2009 Elsevier Ltd. All rights reserved.
关键词:
nickel-base superalloy;temperature creep-properties;uniaxial stress;alloy;parameters;morphology;apparent
Physica B-Condensed Matter
When the Schrodinger equation in quantum mechanics is replaced by the nonlinear Schrodinger equation to describe microscopic particles in nonlinear quantum systems, it has been verified that the nature of the particles differs considerably from those in quantum mechanics, where they are localized and have also wave-corpuscle duality due to the nonlinear interactions. In this case the influences of externally applied potentials in the nonlinear Schrodinger equation on the natures of the microscopic particles have been studied by a perturbation theory. The studied results show that the external potential can change the states of the microscopic particles, such as the positions, amplitude and wave forms, but cannot change the wave-corpuscle duality. In the meanwhile, we find further that the relationship between the external potential and change of positions of the particle satisfies the rule of motion of classical particles. Thus we know from this study that the kinetic energy term, ((h) over bar (2)/2m)del(2)phi, in the nonlinear Schrodinger equation can only make the microscopic particles have a wave feature, but the nonlinear interaction b vertical bar phi vertical bar(2)phi determines its corpuscle feature, their combination makes the microscopic particles have a wave-corpuscle duality, and the potential V((r) over right arrow, t)phi changes only the positions, amplitude and wave form of the particles. Therefore the nonlinear interaction plays an important role in determination of the wave-corpuscle duality of microscopic particles in quantum theory. (C) 2010 Published by Elsevier B.V.
关键词:
Microscopic particle;Schrodinger equation;External potential;wave-corpuscle duality;Nonlinear interaction;Quantum mechanics;schrodinger-equation
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:
Wei GUO
,
Yaping ZONG
,
Gang WANG
,
Liang ZUO
材料科学技术（英文）
The effects of applied tensile strain on the coherent α2 →O-phase transformation in Ti-Al-Nb alloys are explored by computer simulation using a phase-field method. The focus is on the influence of the applied strain direction on the microstructure and volume fraction of the O-phase precipitates. It is found that altering applied strain direction can modify microstructure of Ti-25Al-10~12Nb (at.~pct) alloy duringα2 →O-phase transformation effectively and full laminate microstructure in the Ti-25Al-10Nb (at. pct) alloy can be realized by an applied strain only along the direction 30° away from theα2 phase <10 0> in magnitude equivalent to the stress-free transformation strain. The simulation also shows that not only the magnitude of applied strain but also the applied strain direction influences the O-phase volume fraction and the effect of strain direction on the volume fraction is up to 25%.
关键词:
Phase field simulation
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null
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null
LI Jin WANG Zengfu KE Wei Corrosion Science Laboratory
,
Institute of Corrosion and Protection of Metals
,
Academia Sinica
,
Shenyang
,
China Institute of Corrosion and Protection of Metals
,
Academia Sinica
,
Shenyang 110015
,
China
金属学报(英文版)
Influence of applied potentials and loading waveform on the fatigue crack growth for steel A537 in 3.5% NaCl solution,and corresponding straining electrode behaviour have been studied.Under the applied potentials over or below -800mV(SCE),the anodic dissolution or the hydrogen embrittlement is predominatant,respectively.For applied anodic potential,the acceleration effect of continuous loading pattern on the CF crack growth mainly appeared at the range of low ΔK values,while for cathodic potential,it appeared at the high ΔK values.The continuous straining causes a decrease of natural potential and an increase of anodic dissolution current.
关键词:
corrosion fatigue
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null
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null
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null
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null
Journal of Physics D-Applied Physics
The dynamic aspects of linear elastic fracture mechanics applied to dielectric breakdown are studied. In the same direction as the fracture mechanics analogue for dielectric breakdown described previously by some researchers, this paper develops the intrinsic, rate-dependent bond breakdown micromechanism to account for the dynamic process of dielectric breakdown. The formulae of conducting microcrack growth rate and lifetime prediction are derived and applied to the experimental data of SiO2 films.
关键词:
sio2-films;oxides
