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Journal of Materials Science & Technology 2020年第24期59卷 173-179页

作者： H.Dong Y.Z.Chen Z.R.Zhang G.B.Shan W.X.Zhang f.liu State Key Lab.of Solidification Processing Northwestern Polytechnical UniversityXi’an 710072China Yangtze River Delta Research Institute of NPU Taicang 215400China

The eutectic Ag-Cu alloys exhibiting fine Ag-Cu lamellar eutectic structure formed upon rapid solidification have great potentials being used in various engineering ***,the desired fine primary lamellar eutectic structure(PLES)is usually replaced by a coarse anomalous eutectic structure(AES)when the undercooling prior to solidification exceeds a certain *** forming mechanism of AES in the undercooled eutectic Ag-Cu alloy has been a controversial *** this work,the undercooled Ag-39.9 at.% Cu eutectic alloy is solidified under different cooling conditions by using techniques of melt fluxing and copper mold *** results show that the coupled eutectic growth of this alloy undergoes a transition from a slow eutectic-cellular growth(ECG)to a rapid eutectic-dendritic growth(EDG)above a undercooling of 72 K,accompanying with an abrupt change of the distribution and amount of AES in as-solidified *** kinds of primary lamellar eutectic structures are formed by ECG and EDG during recalescence,*** destabilization of PLES that causes the formation of AES is ascribed to two different mechanisms based on the microstructural examination and theoretical *** 72 K,the destabilization of PLES formed by slow ECG is caused by the mechanism of"termination migration"driven by interfacial *** above 72 K,the destabilization of PLES formed by rapid EDG is attributed to the unstable perturbation of interface driven by interfacial energy and solute supersaturation.

关键词： Ag-Cu alloys Rapid solidification Undercooling Eutectics Destabilization

Influence of Al_2O_3 particle pinning on thermal stability of nanocrystalline fe

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Journal of Materials Science & Technology 2018年第4期34卷 599-604页

作者： G.B.Shan Y.Z.Chen M.M.Gong H.Dong B.Li f.liu State Key Laboratory of Solidification Processing Northwestern Polytechnical University

Second-phase particle pinning has been well known as a mechanism impeding grain boundary （GB） migration, and thus, is documented as an efficient approach for stabilizing nanocrystalline （NC） materials at elevated temperatures. The pinning force exerted by interaction between small dispersed particles and GBs strongly depends on size and volume fraction of the particles. Since metallic oxides, e.g. Al2O3, exhibit great structural stability and high resistance against coarsening at high temperatures, they are expected as effective stabilizers for NC materials. In this work, NC composites consisting of NC fe and Al2O3 nanoparticIes with different amounts and sizes were prepared by high energy ball milling and annealed at various temperatures （Tann） for different time periods （tann）. Microstructures of the ball milled and annealed samples were examined by X-ray diffraction and transmission electron microscopy. The results show that the addition of Al2O3 nanoparticles not only enhances the thermal stability of NC fe grains but also reduces their coarsening rate at elevated temperatures, and reducing the particle size and/or increasing its amount enhance the stabilizing effect of the Al2O3 particles on the NC fe grains.

关键词： Iron Nanocrystalline materials Ball milling Zener pinning Grain growth Thermal stability

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

Kinetics and microstructural modeling of isothermal austenite-to-ferrite transformation in fe-C-Mn-Si steels

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Journal of Materials Science & Technology 2019年第8期35卷 1753-1766页

作者： S.J.Song W.K.Che J.B.Zhang L.K.Huang S.Y.Duan f.liu State Key Laboratory of Solidification Processing Northwestern Polytechnical University

During the multi-stage processing of advanced high-strength steels, the austenite-to-ferrite transformation, generally as a precursor of the formation of other non-equilibrium or metastable structures, has a severe effect on the subsequent phase transformations. Herein, a more flexible kinetic and microstructural predictive modeling for the key austenite-to-ferrite transformation of fe-C-Mn-Si steels was developed,in combination with the classical nucleation theory, the general mixed-mode growth model based on Gibbs energy balance, the microstructural path method and the kinetic framework for grain boundary nucleation. Adopting a bounded, extended matrix space corresponding to a single ferrite grain, both softimpingement and hard-impingement can be naturally included in the current modeling. Accordingly, this model outputs the ferrite volume fraction, the austenite/ferrite interface area per unit volume, and the average grain size of ferrite, which will serve as the input parameters for modeling the subsequent bainite or martensite transformations. Applying the model, this work successfully predicts the experiment measurement of the isothermal austenite-to-ferrite transformation in fe-0.17 C-0.91 Mn-1.03 Si(wt%) steel at different temperatures and explains why the final-state average grain size of ferrite has a maximum at the moderate annealing temperature. Effectiveness and advantages of the present model are discussed arising from kinetics and thermodynamics accompanied with nucleation, growth and impingement.

关键词： Isothermal austenite-ferrite transformation Kinetics Thermodynamics Microstructural modeling Low-alloy steel

Effects of concurrent grain boundary and surface segregation on the final stage of sintering: the case of Lanthanum doped yttriastabilized zirconia

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Journal of Materials Science & Technology 2017年第3期33卷 251-260页

作者： M.M.Gong S.Dey L.J.Wu C.H.Chang H.Li R.H.R.Castro f.liu State Key Laboratory of Solidification Processing Northwestern Polytechnical University Xi＇an 710072 China Department of Materials Science ＆ Engineering University of California Davis CA 95616 USA

Dopants play a critical role in tailoring the microstructure during sintering of compacts. These dopants may form solid solution within the bulk, and/or segregate to the grain boundaries（GBs） and the solidvapor interfaces（free surfaces）, each causing a distinct energetic scenario governing mass transports during densification and grain growth. In this work, the forces controlling the dopant distribution, in particular the possibility of concurrent segregation at both surfaces and GBs, are discussed based on the respective enthalpy of segregation. An equation is derived based on the minimum Gibbs energy of the system to determine enthalpy of segregation from experimental interface energy data, and the results applied to depict the role of La as a dopant on the interface energetics of yttria stabilized zirconia during its final stage of sintering. It is shown that La substantially decreases both GB and surface energies（differently）as sintering progresses, dynamically affecting its driving forces, and consequent grain growth and densification in this stage.

关键词： Grain boundary(GB) segregation Surface segregation Enthalpy of segregation GB energy Surface energy

Effects of dealloying and heat treatment parameters on microstructures of nanoporous Pd

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Journal of Materials Science & Technology 2020年第13期47卷 123-129页

作者： Y.Z.Chen X.Y.Ma W.X.Zhang H.Dong G.B.Shan Y.B.Cong C.Li C.L.Yang f.liu State Key Lab.of Solidification Processing Northwestern Polytechnical University710072 Xi’anChina

Microstructures of nanoporous Pd are essentially important for its physical and chemical *** this work,we show that the microstructures of nanoporous Pd can be tuned by adjusting compositions of the precursor alloys,and dealloying and heat treatment *** the ligament and pore sizes decrease with increasing the electrochemical potential upon dealloying and the concentration of noble component in the precursor *** treatment causes coarsening of the nanoporous *** a critical temperature,the nanoporous structures are subjected to significant *** the critical temperature,surface diffusion is believed to dominate the coarsening *** the critical temperature,the nanoporous structure coarsens remarkably at a rather high rate,which is ascribed to a multiple-mechanism controlled process.

关键词： Nanoporous metals Microstructure Dealloying Kinetics Coarsening

Enhanced mechanical performance of grain boundary precipitation-hardened high-entropy alloys via a phase transformation at grain boundaries

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Journal of Materials Science & Technology 2021年第27期86卷 271-284页

作者： Y.L.Qi L.Zhao X.Sun H.X.Zong X.D.Ding f.Jiang H.L.Zhang Y.K.Wu L.He f.liu S.B.Jin G.Sha J.Sun State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an710049China Analytical&Testing Center Northwestern Polytechnical UniversityXi’an710072China School of Materials Science and Engineering Nanjing University of Science and TechnologyNanjing210094China

Grain-boundary(GB)precipitation has a significant adverse effect on plasticity of alloys,which easily leads to catastrophic intergranular failure in safety-critical applications under high external ***,we report a novel strategy that uses the local stress concentration induced by GB precipitates as a driving force to trigger phase transformation of preset non-equiatomic high-entropy solid-solution phase at *** in situ deformation-induced phase transformation at GBs introduces a well-known effect:transformation-induced plasticity(TRIP),which enables an exceptional elongation to fracture(above 38%)at a high strength(above 1.5 GPa)in a GB precipitation-hardened high-entropy alloy(HEA).The present strategy in terms of"local stress concentration-induced phase transformations at GBs"may provide a fundamental approach by taking advantage of(rather than avoiding)the GB precipitation to gain a superior combination of high strength and high ductility in HEAs.

关键词： Non-equiatomic Grain-boundary precipitation High-entropy alloys Ductility Transformation-induced plasticity

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

Mapping of intim al proliferation in vessels with m ultiple palm azschatzstents :insight fro m an intravascular ultrasound study

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Chinese Medical Journal 1999年第9期112卷 43-43页

作者： f.liu JGe D.Baumgart M.Haude D.WelgeandR.Erbel Department of Cardiology University of Essen Essen Germany

studies indicated that restenosis rate was higher after multiple stents implantation than single stent. Restenosis following stent is mainly due to neointimal hyperplasia and takes place frequently at sites between the stents (In between) and at the central articulation (CA) of Palmaz Schatz stents. To understand this process, we compared serial [post intervention and follow up (fU, 6±2 months)] intravascular ultrasound studies in 86 stents implanted into 30 native and 11 saphenous vein graft lesions. Each lesion had more than one stent (16?mm long) placed closely to each other. Lumen and stent areas (mm 2) were measured; plaque (stent lumen) area, late lumen loss (D lumen area) and tissure growth (D plaque area) were calculated for the edges, bodys, In between, and CA of all stents. The lumen at sites between the stents and at the central articulation are smaller than at the bodys or edges of the stents because of slightly smaller stent area and superimposed prolapse of tissue through the sites between thestents and through the central articulation. Subsequent accumulation of neoimtimal tissue is uniformly throughout the stent. [BHDfG1*2,WK7,WK5,WK4。2,WK5,WK5W]EdgeBodyCAIn betweenANOVA P [BHDZG1*2,WK7ZQ,WK5,WK4。2,WK5,WK5ZQ*3/5W]Post stent area10.3±2.59.4±2.39.2±3.09.1±3.1fU stent area9.7±3.19.3±3.19.0±3.58.9±3.70.001[BH,WK7ZQ,WK5,WK4。2,WK5,WK5W]Post lumen area10.1±2.69.3±3.29.0±3.98.6±4.1fU lumen area6.9±3.76.4±3.55.9±4.15.4±3.8fU palque area2.9±2.13.1±1.93.2±2.43.4±2.50.002Late lumen loss3.2±2.12.9±2.03.1±2.83.3±2.6NSTissue growth2.7±2.52.8±2.32.8±2.52.9±2.6NS Serial intravascular ultrasound imaging shows that restenosis at the locations between the stents (compared to the edges or body) of Palmaz Schatz is the result of smaller initial lumen and tissue prolapse (similar as at CA) and not due to an increased neointimal tissue accumula

关键词： intravascular schatzstents insight Mapping

Distribution ofintimal proliferation in long lesions covered with multiplestents:insightfrom an intravascular ultrasound study

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Chinese Medical Journal 1999年第9期112卷 59-59页

作者： f.liu JGe D.Welge M.Hauda D.BaumgartandR.Erbel Department of Cardiology University Essne Essne German

Angiographic studies show higher restenosis rates in long lesions covered with multiple stents. To understand this process,we compared serial [post intervention and follow up (fU,6±3 months)] intravascular ultrasound (IVUS) studies in 155 various stents implanted into 65 native de novo lesions (>20?mm). Lumen and stent areas (2?mm) were measured; plaque (stent lumen) area,late lumen loss and tissue growth were calculated for the edges, bodys, and connection points (CP) of the stents. Two types of CP were identified: overlapping (OVL) and non overlapping (NOVL). The lumen areas at CP after stent were smaller than those at the bodys or edges because of smaller stent area (OVL) and prolapse of tissue through the sites between the stents (NOVL). Post stent area10.6±2.79.5±2.59.0±2.89.1±3.0fU stent area9.8±3.09.4±3.18.8±3.68.9±3.50.0029.8±3.09.4±3.18.8±3.68.9±3.50.0029.4±3.18.8±3.68.9±3.50.0028.8±3.68.9±3.50.0028.9±3.50.0020.0020.00210.3±2.79.4±3.38.5±4.18.7±3.7fU lumen area7.1±3.66.6±3.45.5±3.75.8±4.2fU plaque area3.0±2.13.2±2.03.3±2.43.4±2.30.002Late lumen loss3.2±2.22.8±2.13.0±2.73.2±2.7NSTissue growth2.8±2.62.7±2.42.8±2.52.9±2.6NS Serial IVUS imaging shows that restenosis at the connection point is the result of smaller initial lumen (OVL and NOVL) and tissue prolapse (NOVL) and is not due to an increased neointimal accumulation. New design of long stent may reduce stent restenosis in long lesions.

关键词： intravascular covered