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Thermo-kinetic characteristics on stabilizing hetero-phase interface of metal matrix composites by crystal plasticity finite element method

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Journal of Materials Science & Technology 2024年第2期169卷 53-67页

作者： Y.B.Zhang S.J.Song f.liu State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an 710072China Analytical&Testing Center Northwestern Polytechnical UniversityXi’an 710072China

Using dislocation-based constitutive modeling in three-dimension crystal plasticity finite element(3D CPfE)simulations,co-deformation and instability of hetero-phase interface in different material systems were herein studied for polycrystalline metal matrix composites(MMCs).Local stress and strain fields in two types of 3layer MMCs such as fcc/fcc Cu-Ag and fcc/bcc Cu-Nb have been predicted under simple compressive ***,more severe strain-induced interface instability can be observed in the fcc/bcc systems than in the fcc/fcc systems upon refining to metallic nanolayered composites(MNCs).By detailed analysis of stress and strain localization,it has been demonstrated that the interface instability is always accompanied by high-stress concentration,i.e.,thermodynamic characteristics,or high strain prevention i.e.,kinetic characteristics,at the hetero-phase *** then follows that the thermodynamic driving forceG and the kinetic energy barrier Q during dislocation and shear banding can be adopted to classify the deformation modes,following the so-called thermo-kinetic *** by inserting a high density of high-energy interfaces into the Cu-Nb composites,such thermo-kinetic integration at the hetero-phase interface allows a successful establishment of MMCs with the high△G-high Q deformation mode,which ensures high hardening and uniform strain distri-bution,thus efficiently suppressing the shear band,stabilizing the hetero-phase interface,and obtaining an exceptional combination in strength and *** hetero-phase interface chosen by a couple of thermodynamics and kinetics can be defined as breaking the thermo-kinetic correlation and has been proposed for artificially designing MNCs.

关键词： Thermodynamics and kinetics Physics-based constitutive modeling Hetero-phase interface Crystal plasticity finite element

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Dislocation ordering and texture strengthening of naturally aged Al-Cu-Mg alloy

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Journal of Materials Science & Technology 2022年第23期118卷 1-14页

作者： f.liu Z.Y.liu G.Y.He L.N.Ou School of Materials Science and Engineering Central South UniversityChangsha 410083China Key Laboratory of Nonferrous Metal Materials Science and Engineering Ministry of EducationCentral South UniversityChangsha 410083China National Key Laboratory of Science and Technology on High-Strength Structural Materials Central South UniversityChangsha 410083China

Stability of grain structure,dislocation ordering and strengthening mechanisms of the naturally aged AlCu-Mg alloy after solution treatment are investigated by using optical microscope(OM),scanning electron microscope(SEM),electron back-scattered diffraction(EBSD),X-ray diffraction(XRD) and transmission electron microscope(TEM).Results show that {100},{100},{110} and {110}slip systems can be activated after solution treatment,which can promote the formation of {110}Goss *** combination effect of T-Al_(20)Cu_(2) Mn_(3) phase and Goss-oriented grains with large Taylor factor makes the solution-treated alloys display excellent stability of grain *** enhanced yield strength of the alloy is ascribed to grain-refine strengthening,dispersed particles strengthening,dislocation strengthening and texture *** coarsening of the second phase is responsible for softening of the alloy after annealing at 400 ℃+solution treatment at 475 ℃.

关键词： Al-Cu-Mg alloy Dislocation ordering Goss texture Grain structure stability Texture strengthening

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Uncovering the softening mechanism and exploring the strengthening strategies in extremely fine nanograined metals:A molecular dynamics study

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Journal of Materials Science & Technology 2022年第14期109卷 186-196页

作者： H.R.Peng Z.Y.Jian C.X.liu L.K.Huang Y.M.Ren f.liu School of Materials and Chemical Engineering Xi’an Technological UniversityXi’an 710021China State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an 710072China

The strength of polycrystalline metals increases with decreasing grain size,following the classical HallPetch ***,this relationship fails when softening occurs at very small grain sizes(typically less than 10 to 20 nm),which limits the development of ultrahigh-strength *** this work,using columnar-grained nanocrystalline Cu-Ag‘samples’,molecular dynamics simulations were performed to investigate the softening mechanism and explore the strengthening strategies(e.g.,formation of solid solution or grain boundary(GB)segregation)in extremely fine nanograined ***,the softening of pure metals is induced by atomic sliding in the GB layer,rather than dislocation activities in the grain interior,although both occur during *** solid solution lowers the stacking fault energy and increases the GB energy,which leads to the softening of NC *** segregation stabilizes GB structures,which causes a notable improvement in strength,and this improvement can be further enhanced by optimizing the solute concentration and GB *** work deepens the understanding of the softening mechanism due to atomic sliding in the GB layer and the strengthening mechanism arising from tailoring the GB stability of immiscible alloys and provides insights into the design of ultrahighstrength materials.

关键词： Softening Strengthening Cu-Ag alloy Molecular dynamics Nanocrystalline

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Nonlinear Capillary-Gravity Waves Produced by a Vertically Oscillating Plate

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China Ocean Engineering 1998年第2期13卷 147-162页

作者： Philip L.-f.liu Professor Cornell UniversityIthacaNY14853U.S.A.

The nonlinear capillary-gravity wave produced by a vertically oscillating plate, in which the contact-angle model is considered, is studied by use of the Boundary Integral Equation Method (BIEM). The present numerical experiment shows that the code is robust and efficient for modeling the generation and propagation of capillary-gravity waves. It is found that the wave heights of stationary periodic nonlinear waves radiated away from the plate are dependent on the parameters involved in the contact-angle model. The effect of the contact-angle hysteresis and the nonlinearity of capillary-gravity waves on the wave profile is discussed in the paper.

关键词： Boundary Integral Equation Method nonlinear capillary-gravity wave wavemaker

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A strategy for designing stable nanocrystalline alloys by thermo-kinetic synergy

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Journal of Materials Science & Technology 2020年第8期36卷 21-31页

作者： H.R.Peng B.S liu f.liu State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an710072China School of Materials and Chemical Engineering Xi’an Technological UniversityXi’an710021China Analytical and Testing Center Northwestern Polytechnical UniversityXi’an710072China

Aiming to design stable nanocrystalline(NC)materials,so far,it has been proposed to construct nanostructure stability maps in terms of thermodynamic parameters,while kinetic stabilization has seldom been considered,despite the synergy of thermodynamics and ***,the thermodynamically stabilized NC materials may be easily subjected to grain growth at high temperatures due to the weakly kinetic *** from the thermo-kinetic synergy,a stabilization criterion is proposed as a function of intrinsic solute parameters(*** activation energy for bulk diffusion and the segregation enthalpy),intrinsic solvent parameters(*** intrinsic activation energy for GB migration and the GB energy)and processing parameters(*** grain size,the temperature and the solute concentration).Using first-principles calculations for a series of combinations between fifty-one substitutional alloying atoms as solute atoms and fe atom as fixed solvent atom,it is shown that the thermal stability neither simply increases with increasing the segregation enthalpy as expected by thermodynamic stabilization,nor monotonically increases with increasing the activation energy for bulk diffusion as described by kinetic *** combination of thermodynamic and kinetic contributions,the current stabilization criterion evaluates quantitatively the thermal stability,thus permitting convenient comparisons among NC materials involved by various combinations of the solute atoms,the solvent atoms,or the processing *** of this thermo-kinetic stabilization criterion has been tested by current experiment results of fe-Y alloy and previously published data of fe-Ni,fe-Cr,fe-Zr and fe-Ag alloys,etc.,which opens a new window for designing NC materials with sufficiently high thermal stability and sufficiently small grain size.

关键词： Thermo-kinetic Synergy Criterion Thermal stability Nanocrystalline materials

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Euler Solutions Using Approximate Boundary Conditions for Thin Airfoil with Small Oscillations

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西北工业大学学报 2003年第6期21卷 683-686页

作者： Gao Chao Luo Shijun f.liu CollegeofAeronautics NorthwesternPolytechnicalUniversityXi′an710072 DepartmentofMechanicalandAerospaceEngineering UniversityofCaliforniaIrvineCA92697-3975USA

This paper presents an efficient numerical method for solving the unsteady Euler equations on stationary Cartesian grids. Wall boundary conditions are implemented on non moving mean wall positions by assuming the airfoil being thin and undergoing small deformation, but the mean angle of attack of the body can still be large and we use the full nonlinear Euler equation in the field for accurate resolution of shock waves and vorticity. The method does not require the generation of moving body fitted grids and thus can be easily deployed in any fluid structure interaction problem involving relatively small deformation of a thin body. We use the first order wall boundary conditions in solving the full Euler equation. Unsteady transonic flow is calculated about an oscillating NACA 0012 airfoil at free stream Mach number M ∞ =0.755, mean angle of attack α m =0.016, amplitude of pitching oscillation α 0 =2.51, reduced frequency κ = 0.081 4. The computed results, including surface pressure distribution, instantaneous lift and moment coefficients are compared with known experimental data. It is shown that the first order boundary conditions are satisfactory for airfoils of typical thicknesses with small deformation for unsteady calculations.

关键词：欧拉方程近似边界条件薄型机翼小幅度摆动不稳定流

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Recent Advancement in Modeling Seafloor Dissipative Mechanism in Shallow Water

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China Ocean Engineering 2008年第1期22卷 1-10页

作者： Philip L.-f.liu Yong Sung PARK School of Civil and Environmental Engineering Cornell University

In this paper, the recent development in modeling seabed dissipative mechanisms in shallow water is reviewed. Specifically, laminar and turbulent boundary layer solutions as well as viscous mud flow solutions under transient waves are presented. These analytical solutions are compared with experimental data for both solitary waves and cnoidal waves. Very goed agreement is ohtained. The Boussinesq equations with boundary layer effects and the muddy seabed effects are also shown.

关键词： seabed dissipative mechardsms boundary layer Boussinesq equations

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Solution of the Euler Equations with Approximate Boundary Conditions for Thin Airfoils

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西北工业大学学报 2003年第3期21卷 253-258页

作者： Gao Chao Luo Shijun f.liu DepartmentofAircraftEngineering NorthwesternPolytechnicalUniversityXi′an710072 DepartmentofMechanicalandAerospaceEngineering UniversityofCaliforniaIrvineCA92697-3975USA

This paper presents an efficient numerical method for solving the Euler equations on rectilinear grids. Wall boundary conditions on the surface of an airfoil are implemented by using their first order expansions on the airfoil chord line, which is placed along a grid line. However, the method is not restricted to flows with small disturbances since there are no restrictions on the magnitude of the velocity or pressure perturbations. The mathematical formulation and the numerical implementation of the wall boundary conditions in a finite volume Euler code are described. Steady transonic flows are calculated about the NACA 0006, NACA 0012 and NACA 0015 airfoils, corresponding to thickness ratios of 6%, 12%, and 15%, respectively. The computed results, including surface pressure distributions, the lift coefficient, the wave drag coefficient, and the pitching moment coefficient, at angles of attack from 0° to 8° are compared with solutions at the same conditions by fLO52, a well established Euler code using body fitted curvilinear grids. Results demonstrate that the method yields acceptable accuracies even for the relatively thick NACA 0015 airfoil and at high angles of attack. This study establishes the potential of extending the method to computing unsteady fluid structure interaction problems, where the use of a stationary rectilinear grid offers substantial advantages in both computer time and human work since it would not require the generation of time dependent body fitted grids.

关键词： Euler方程近似边界条件薄翼剖面直线栅格流体动力学控制方程虚拟格值扰动

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STCf conceptual design report (Volume 1): Physics & detector

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frontiers of physics 2024年第1期19卷 1-154页

作者： M.Achasov X.C.Ai L.P.An R.Aliberti Q.An X.Z.Bai Y.Bai O.Bakina A.Barnyakov V.Blinov V.Bobrovnikov D.Bodrov A.Bogomyagkov A.Bondar I.Boyko Z.H.Bu f.M.Cai H.Cai J.J.Cao Q.H.Cao X.Cao Z.Cao Q.Chang K.T.Chao D.Y.Chen H.Chen H.X.Chen J.f.Chen K.Chen L.L.Chen P.Chen S.L.Chen S.M.Chen S.Chen S.P.Chen W.Chen X.Chen X.f.Chen X.R.Chen Y.Chen Y.Q.Chen H.Y.Cheng J.Cheng S.Cheng T.G.Cheng J.P.Dai L.Y.Dai X.C.Dai D.Dedovich A.Denig I.Denisenko J.M.Dias D.Z.Ding L.Y.Dong W.H.Dong V.Druzhinin D.S.Du Y.J.Du Z.G.Du L.M.Duan D.Epifanov Y.L.fan S.S.fang Z.J.fang G.fedotovich C.Q.feng X.feng Y.T.feng J.L.fu J.Gao Y.N.Gao P.S.Ge C.Q.Geng L.S.Geng A.Gilman L.Gong T.Gong B.Gou W.Gradl J.L.Gu A.Guevara L.C.Gui A.Q.Guo f.K.Guo J.C.Guo J.Guo Y.P.Guo Z.H.Guo A.Guskov K.L.Han L.Han M.Han X.Q.Hao J.B.He S.Q.He X.G.He Y.L.He Z.B.He Z.X.Heng B.L.Hou T.J.Hou Y.R.Hou C.Y.Hu H.M.Hu K.Hu R.J.Hu W.H.Hu X.H.Hu Y.C.Hu J.Hua G.S.Huang J.S.Huang M.Huang Q.Y.Huang W.Q.Huang X.T.Huang X.J.Huang Y.B.Huang Y.S.Huang N.Hüsken V.Ivanov Q.P.Ji J.J.Jia S.Jia Z.K.Jia H.B.Jiang J.Jiang S.Z.Jiang J.B.Jiao Z.Jiao H.J.Jing X.L.Kang X.S.Kang B.C.Ke M.Kenzie A.Khoukaz I.Koop E.Kravchenko A.Kuzmin Y.Lei E.Levichev C.H.Li C.Li D.Y.Li f.Li G.Li G.Li H.B.Li H.Li H.N.Li H.J.Li H.L.Li J.M.Li J.Li L.Li L.Li L.Y.Li N.Li P.R.Li R.H.Li S.Li T.Li W.J.Li X.Li X.H.Li X.Q.Li X.H.Li Y.Li Y.Y.Li Z.J.Li H.Liang J.H.Liang Y.T.Liang G.R.Liao L.Z.Liao Y.Liao C.X.Lin D.X.Lin X.S.Lin B.J.liu C.W.liu D.liu f.liu G.M.liu H.B.liu J.liu J.J.liu J.B.liu K.liu K.Y.liu K.liu L.liu Q.liu S.B.liu T.liu X.liu Y.W.liu Y.liu Y.L.liu Z.Q.liu Z.Y.liu Z.W.liu I.Logashenko Y.Long C.G.Lu J.X.Lu N.Lu Q.f.Lü Y.Lu Y.Lu Z.Lu P.Lukin f.J.Luo T.Luo X.f.Luo Y.H.Luo H.J.Lyu X.R.Lyu J.P.Ma P.Ma Y.Ma Y.M.Ma f.Maas S.Malde D.Matvienko Z.X.Meng R.Mitchell A.Nefediev Y.Nefedov S.L.Olsen Q.Ouyang P.Pakhlov G.Pakhlova X.Pan Y.Pan E.Passemar Y.P.Pei H.P.Peng L.Peng X.Y.Peng X.J.Peng K.Peters S.Pivovarov E.Pyata B.B.Qi Y.Q.Qi W.B.Qian Y.Qian C.f.Qiao J.J.Qin J.J.Qin L.Q.Qin X.S.Qin T.L.Qiu J.Rademacker C.f.Redmer H.Y.Sang Anhui University Hefei 230039China Beihang University Beijing 100191China Budker Institute of Nuclear Physics Novosibirsk 630090Russia CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China Cavendish Laboratory University of CambridgeJJ Thomson AveCambridge CB30HEUnited Kingdom Central China Normal University Wuhan 430079China Central South University Changsha 410083China China University of Geosciences Wuhan 430074China China University of Mining and Technology Xuzhou 221116China École Polytechnique fédérale de Lausanne(EPfL) LausanneSwitzerland fudan University Shanghai 200433China Goethe University frankfurt D-60325 Frankfurt am MainGermany Guangxi Normal University Guilin 541004China Guangxi Uninversity Nanning 530004China Hangzhou Institute for Advanced Study UCASHangzhou 310024China Hebei Normal University Shijiazhuang 050024China Hebei University Baoding 071002China Hefei University of Technology Hefei 230601China Helmholtz Institute Mainz Staudinger Weg 18D-55099 MainzGermany Henan Normal University Xinxiang 453007China Henan University Kaifeng 475004China High Energy Physics Center Chung-Ang UniversitySeoul 06974Korea Higher School of Economy 11 Pokrovsky Bulvar Moscow 109028Russia Huangshan University Huangshan 245000China Hubei University of Automotive Technology Shiyan 442002China Hunan Normal University Changsha 410081China Hunan University of Science and Technology Xiangtan 411201China Hunan University Changsha 410082China Indiana University BloomingtonIndiana 47405USA Inner Mongolia University Hohhot 010021China Institute of Advanced Science facilities Shenzhen 518107China Institute of High Energy Physics Chinese Academy of SciencesBeijing 100049China Institute of Modern Physics Chinese Academy of SciencesLanzhou 730000China Institute of Physics Academia SinicaTaipeiTaiwan 11529China Institute of Theoretical Physics Chinese Academy of SciencesBeijing 100190China Jilin University Changch

The superτ-charm facility(STCf)is an electron–positron collider proposed by the Chinese particle physics *** is designed to operate in a center-of-mass energy range from 2 to 7 GeV with a peak luminosity of 0.5×10^(35) cm^(–2)·s^(–1) or *** STCf will produce a data sample about a factor of 100 larger than that of the presentτ-charm factory—the BEPCII,providing a unique platform for exploring the asymmetry of matter-antimatter(charge-parity violation),in-depth studies of the internal structure of hadrons and the nature of non-perturbative strong interactions,as well as searching for exotic hadrons and physics beyond the Standard *** STCf project in China is under development with an extensive R&D *** document presents the physics opportunities at the STCf,describes conceptual designs of the STCf detector system,and discusses future plans for detector R&D and physics case studies.

关键词： electron–positron collider tau-charm region high luminosity STCf detector conceptual design

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Enhanced Mechanical Properties of friction Stir Welded 5083Al-H19 Joints with Additional Water Cooling

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Journal of Materials Science & Technology 2017年第9期33卷 1009-1014页

作者： B.B.Wang f.f.Chen f.liu W.G.Wang P.Xue Z.Y.Ma School of Mechanical Engineering Liaoning Shihua University Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences

3-mm-thick 5083Al-H19 rolled plates were friction stir welded(fSW) at tool rotation rates of 800 and200 rpm with and without additional water cooling. With decreasing the rotation rate and applying water cooling, softening in the fSW joint was significantly reduced. At a low rotation rate of 200 rpm with additional water cooling, almost no obvious softening was observed in the fSW joint, and therefore a fSW5083Al-H19 joint with nearly equal strength to the base material(BM) was obtained. furthermore, the grains in the nugget zone were considerably refined with reducing the heat input and ultrafine equiaxed grains of about 800 nm were obtained in the lowest heat input condition. This work provides an effective method to achieve high property fSW joints of precipitate-hardened and work-hardened Al alloys.

关键词： friction stir welding Aluminum alloy Water cooling Microstructure Mechanical property

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