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Effects of yttria Addition on Microstructure,Mechanical Properties,Wear Resistance and Corrosive Wear Resistance of TiNi Alloy

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Journal of Materials Science & Technology 2009年第5期25卷 645-648页

作者： Hojat Ahmadi D.y.li Meisam Nouri Faculty of Biosystems Engineering University of TehranIran Department of Chemical and Materials Engineering University of AlbertaEdmontonCanada Department of Materials Engineering Tarbiat Modares UniversityTehranIran

TiNi alloy has a high resistance to wear and could be an excellent candidate for various tribological applications. But studies show that oxygen active elements can improve properties of some alloys, markedly. yttrium is one of the oxygen active elements. In this paper, the effects of yttria addition on properties of TiNi have been studied via micro-indentation, hardness, wear and corrosive wear tests. It is demonstrated that by addition of yttria to 5%, TiNi alloy can own improved mechanical properties and resistance to wear and corrosive wear.

关键词： yttria TiNi Mechanical behavior Wear corrosive Wear

Transition of deformation mechanisms from twinning to dislocation slip in nanograined pure cobalt

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Journal of Materials Science & Technology 2022年第26期121卷 124-129页

作者： y.W.Qi Z.P.Luo X.y.li K.Lu Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaHefei 230026China

Deformation mechanisms of nanograined and submicron-grained pure cobalt processed by means of high strain rate shear deformation at cryogenic temperatures were *** analysis revealed a transition of governing deformation mechanism from deformation twinning and dislocation slip in submicron-grains to and dislocations slip in *** tests illustrated that the Hall-Petch relation slope changes consequently with the transition of deformation mechanism.

关键词： Nanograin Cobalt Deformation mechanism Hall-Petch relation

Oxidation behavior of cobalt nanoparticles studied by in situ environmental transmission electron microscopy

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Science Bulletin 2017年第11期62卷 775-778页

作者： Dejiong Zhang Chuanhong Jin Z.y.li Ze Zhang Jixue li State Key Laboratory of Silicon Materials School of Materials Science and EngineeringZhejiang University Nanoscale Physics Research Laboratory School of Physics and AstronomyUniversity of Birmingham

The dynamics of oxidation of cobalt nanoparticles were directly revealed by in situ environmental transmission electron ***,cobalt nanoparticles were oxidized to polycrystalline cobalt monoxide,then to polycrystalline tricobalt tetroxide,in the presence of oxygen with a low partial *** cavities(or voids) were formed during the oxidation,owing to the Kirkendall *** of the oxides growth suggested that the oxidation of cobalt nanoparticles followed a parabolic rate law,which was consistent with diffusion-limited *** situ transmission electron microscopy allowed potential atomic oxidation pathways to be *** outward diffusion of cobalt atoms inside the oxide layer controlled the oxidation,and formed the hollow *** by the electron beam,which destroyed the sealing effect of graphite layer coated on the cobalt surface and resulted in fast oxidation rate,played an important role in activating and promoting the *** findings further our understanding on the microscopic kinetics of metal nanocrystal oxidation and knowledge of energetic electrons promoting oxidation reaction.

关键词： Cobalt Nanoparticle Oxidation dynamics Parabolic rate Environmental transmission electron microscopy (ETEM) Electron irradiation

Corrosion behavior of 13Cr stainless steel under stress and crevice in high pressure CO_(2)/O_(2)environment

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Journal of Materials Science & Technology 2021年第29期88卷 79-89页

作者： G.y.Zhu y.y.li B.S.Hou Q.H.Zhang G.A.Zhang Key Laboratory of Material Chemistry for Energy Conversion and Storage Ministry of EducationHubei Key Laboratory of Materials Chemistry and Service FailureSchool of Chemistry and Chemical EngineeringHuazhong University of Science and TechnologyWuhan430074China

In this work,through the self-developed setup for in situ electrochemical tests,the corrosion behavior of 13 Cr stainless steel under the combined effect of stress and crevice in high pressure CO_(2)/O_(2)environment was *** results show that 13 Cr stainless steel presents a self-passivation *** the action of stress,the anodic dissolution process of steel inside crevice is *** is a galvanic effect between the stressed steel inside crevice and the unstressed steel outside *** applied stress reduces the induction stage of crevice corrosion and induces a larger galvanic current,i.e.,the applied stress promotes the development of crevice ***,adding 0.1 MPa O_(2)is conducive to forming a more stable passive film but causes a greater galvanic effect.

关键词： Stainless steel Crevice corrosion Stress corrosion Galvanic effect

Magnetic and Transport Properties of Mn_(0.98)Cr_(0.02)Te Epitaxial Films Grown on Al_2O_3 Substrates

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Journal of Materials Science & Technology 2014年第2期30卷 103-106页

作者： Z.H.Wang D.y.Geng J.li y.B.li Z.D.Zhang Shenyang National Laboratory for Materials Science Institute of Metal Researchand International Centre for Materials PhysicsChinese Academy of Sciences Changchun Institute of Optics Fine Mechanics and PhysicsChinese Academy of Sciences

The epitaxial Mno0.98Cr0.02Te films on single crystal Al2O3 （0001） substrates were prepared by pulsed laser deposition. The X-ray diffraction and scanning electron microscopy results showed that the good continuous epitaxial film was obtained with substrate temperature of 500 ℃. When the substrate temperature reached 700 ℃, the film was island growth and the manganese oxides phase appeared. The temperature dependence of both the magnetization and electrical resistance showed a sharp rise at around 60 K due to the magnetoelastic coupling. The temperature dependence of the electrical resistance of Mno0.98Cr0.02Te provided evidence for a transition from the metallic to semiconducting state at 305 K due to the spin disorder scattering with a large contribution from the influence of magnon drag.

关键词： Magnetic properties Mno0.98Cr0.02Te films X-ray diffraction Epitaxial film

An Efficient and Convenient Cyclization Method for the Synthesis of Flavans

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Chinese Chemical Letters 1998年第9期9卷 805-807页

作者： Hou, LM Huang, CS Cen, W li, y li, yL Lanzhou Univ Inst Organ Chem Lanzhou 730000 Peoples R China Lanzhou Univ Natl Lab Appl Organ Chem Lanzhou 730000 Peoples R China Qingdao Univ Dept Chem Qingdao 266071 Peoples R China

A convenient cyclization method for the flavans synthesis is described. BF3 was used for the first time as an efficient catalyst to effect the cyclization of 1,3-diarylpropan-1-ols.

关键词： flavans cyclization synthesis

A THEORy OF EFFECTIVE THERMAL CONDUCTIVITy FOR MATRIX-INCLUSION-MICROCRACK THREE-PHASE HETEROGENEOUS MATERIALS BASED ON MICROMECHANICS

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Acta Mechanica Solida Sinica 2000年第2期13卷 179-187页

作者： Zhang, QJ Zhai, PC li, y Wuhan Univ Technol State Key Lab Adv Technol Mat Synth & Proc Wuhan 430070 Peoples R China

The effective thermal conductivity of matrix-inclusion-microcrack three-phase heterogeneous materials is investigated with a self-consistent micromechanical method (SCM) and a random microstructure finite element method(RMFEM). In the SCM, microcracks are assumed to be randomly distributed and penny-shaped and inclusions to be spherical, the crack effect is accounted for by introducing a crack density parameter, the effective thermal conductivity is derived which relates the macroscopic behavior to the crack density parameter. In the RMFEM, the highly irregular microstructure of the heterogeneous media is accurately described, the interaction among the matrix-inclusion-microcracks is exactly treated, the inclusion shape effect and crack size effect are considered. A Ni/ZrO2 particulate composite material containing randomly distributed, penny-shaped cracks is examined as an example. The main results obtained are: (1) the effective thermal conductivity is sensitive to the crack density and exhibits essentially a linear relationship with the density parameter: (2) the inclusion shape has a significant effect on the effective thermal conductivity and a polygon-shaped inclusion is more effective in increasing or decreasing the effective thermal conductivity than a sphere-shaped one; and (3) the SCM and RMFEM are compared and the two methods give the same effective property in the case in which the matrix thermal conductivity A, is greater than the inclusion one lambda(2). In the inverse case of lambda(1) y are low and differ as they are high. A reasonable explanation for the agreement and deviation between the two methods in the case of lambda(1) < lambda(2) is made.

关键词： effective thermal conductivity heterogeneous materials microcracks micromechanics

THE CURVED BAR SUBJECTED TO AN ARBITRARILy DISTRIBUTED LOADING:ANOTHER PARADOX IN THE TWO-DIMENSIONAL THEORy OF ELASTICITy

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Acta Mechanica Solida Sinica 1996年第3期9卷 253-262页

作者： Ding, HJ Peng, NL li, y ZHEJIANG UNIV DEPT CIVIL ENGNHANGZHOU 310027PEOPLES R CHINA NANCHANG UNIV INST ENGN MECHNANCHANG 330029PEOPLES R CHINA BOSTON UNIV BOSTONMA 02215

The problem of the curved bar subjected to an arbitrarily distributed loading on the surfaces r=a and r=b is sp!ved by using the method of complex functions and expanding the boundary conditions at r=a and r=b into Fourier series. Then another paradox in the two-dimensional theory of elasticity is discovered, i. e., the classical solution becomes infinite when the curved bat is subjected to a uniform loading or when the angle included between the two ends of the curved bar 2 alpha is equal to 2 pi and the curved bar is subjected to a sine or cosine loading. In this paper the paradox is resolved successfully and the solutions for the paradox ate obtained. Moreover, the modified classical solution which remains bounded as 2 alpha approaches 2 pi is provided.

关键词： curved bar paradox elasticity

An insight into Mg alloying effects on Cu thin films:microstructural evolution and mechanical behavior

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Journal of Materials Science & Technology 2020年第22期54卷 101-112页

作者： G.y.li L.F.Cao J.y.Zhang X.G.li y.Q.Wang K.Wu G.liu J.Sun State Key Laboratory for Mechanical Behavior of Materials Xi'an Jiaotong UniversityXi'an710049China International Joint Laboratory for light Alloys(Ministry of Education) College of Materials Science and EngineeringChongqing UniversityChongqing400044China Electron Microscopy Center of Chongqing University Chongqing UniversityChongqing400044China

How to design ultra-strong,light-weight Cu alloys is a long-term pursuit in materials community,which is technically superior and cost-effective for their promising energy-saving *** this work,we prepared Cu-Mg alloyed thin films to study light element Mg alloying effects on the microstructure,hardness and strain rate sensitivity(SRS) of nanocrystalline Cu thin *** the studied Mg concentrationrange spanning from 0 at.% to 16.8 at.%,both the grain size and the twin spacing decrease monotonously with increasing Mg composition while Cu-2.8 at.% Mg sample has the highest twin fraction of ~75%.A combined strengthening model was employed to quantify the Mg concentration-dependent hardness of nanotwinned(NT) Cu-Mg thin films,in which the grain/twin boundary facilitates strengthening while the solute Mg atoms induce *** the constant rate of loading tests and the nanoindentation creep tests uncover that compared with pure Cu samples,the NT Cu-Mg thin films manifest much lower SRS,particularly in the creep tests,owing to the activation of dynamic strain aging effects.

关键词： Cu-Mg thin films Microstructure evolution Creep tests Hardness Strain rate sensitivity