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Acta Metallurgica Sinica(English Letters) 2008年第3期21卷 183-190页

作者： W. liu C.q. Wang y.H. Tian M.y. Li Department of Electronics Packaging Technology State Key Lab of Advanced Welding Production Technology Harbin Institute of Technology Harbin 150001 China Shenzhen Graduate School of Harbin Institute of Technology Shenzhen 518055 China

Formation of AuSnx intermetallic compounds （IMCs） in laser reflowed solder joints was investigated. The results showed that few IMCs formed at the solder/0. 1μm Au interface. Needlelike AuSn4 IMCs were observed at the solder/0.5μm Au interface. In Sn-2.0Ag-O,75Cu-3,0Bi and Sn-3.5Ag-O.75Cu solder joints, when the laser input energy was increased, AuSn4 IMCs changed .from a layer to needlelike or dendritic distribution at the solder/0.9μm Au interface. As for the solder joints with 4.0 μm thickness of Au surface finish on pads, AuSn4 , AuSnx, AuSn IMCs, and Au2Sn phases formed at the interface. Moreover, the content of AuSnx IMCs, such as, AuSn4 and AuSn2, which contained high Sn concentration, would become larger as the laser input energy increased. In the Sn-37Pb solder joints with 0.9 μm or 4.0 μm thickness of the Au surface finish on pads, AuSn4 IMCs were in netlike distribution. The interspaces between them were filled with Pb-rich phases.

关键词： Laser soldering Inlermetallics Au films

Finite Element Prediction of the Thermal Conductivity of GNP/Al Composites

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Acta Metallurgica Sinica(English Letters) 2022年第5期35卷 825-838页

作者： X.S.yang L.Zhou K.y.liu Z.y.liu q.Z.Wang B.L.Xiao Z.y.Ma School of Electromechanical and Automotive Engineering Yantai UniversityYantai264005China Shi-Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang110016China

A 3 D multi-scale finite element model was developed to predict the effective thermal conductivity of graphene nanoplatelet(GNP)/Al *** factors influencing the effective thermal conductivity of the GNP/Al composites were investigated,including the orientation,shape,aspect ratio,configuration and volume fraction of *** results show that GNPs shape has a little influence on the thermal conductivity of GNP/Al composites,and composites with elliptic GNPs have the highest thermal *** addition,with increasing the aspect ratio of GNPs,the thermal conductivity of GNP/Al composites increases and finally tends to be *** GNPs configuration strongly influences the thermal conductivity of GNP/Al composites,and the thermal conductivity of the composites with layered GNPs is the highest among the five *** effective thermal conductivity is sensitive to volume fraction of ***,when the volume fraction of layered GNPs reaches 1.54%,the thermal conductivity of GNP/Al composites is as high as 400 W/m *** findings of this study could provide a good theoretical basis for designing high thermal conductivity GNP/Al composites.

关键词： Multi-scale finite element model Thermal conductivity GNP/Al composites Shape Aspect ratio Configuration

THE CHARACTERISTICS OF MICROSTRUCTURES AND PROPERTIES FOR ADVANCED ALUMINUM/SILICON CONTAINED HOT-ROLLED TRIP STEELS

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Acta Metallurgica Sinica(English Letters) 2004年第6期17卷 823-829页

作者： y.Chern G.y.Tang W.liu q.liu P.H.Li X.Chen GraduateSchoolatShenzhenofTsinghuaUniversity Shenzhen518055China GraduateSchoolatShenzhenofTsinghuaUniversity Shenzhen518055China／／WuhanIronandSteelGroupCorporationWuhan430080China WuhanIronandSteelGroupCorporation Wuhan430080China

The microstructure characteristics with super fine ferrite grain size less than 5mm, appropriate retained austenite fraction around 5.0% and or removable abundant dislocations have been obtained by controlled rolling and cooling, which leads to well balance com- prehensive properties with high tensile strength of 510 and 615MPa, high elongation of 40% and 27%, low ratio of yield strength to tensile strength 0.83 and 0.80, as well as low ductile- brittle transition temperature less than -80 and -70℃ for advanced aluminum hot-rolled TRIP steel and silicon hot-rolled TRIP steel, respectively.

关键词： super fine ferrite grain removable dislocation retained austenite aluminum silicon hot-rolling TRIP steel

Macroscopic and microscopic mechanical behaviors of climbing tendrils

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Acta Mechanica Sinica 2019年第3期35卷 702-710页

作者： q.Guo J.J.Dong y.liu X.H.Xu q.H.qin J.S.Wang Tianjin Key Laboratory of Modern Engineering Mechanics Department of MechanicsTianjin UniversityTianjin 300054China State Key Laboratory of Nonlinear Mechanics (LNM) Institute of MechanicsChinese Academy of ScienceBeijing 100080China Research School of Engineering Australian National UniversityCanberraACT 2601Australia

Tendril-bearing climbing plants must recur to the tendril helices with chiral perversion or dual chirality for climbing and to obtain sun exposure. Despite researchers' prolonged fascination with climbing tendrils since Darwin's time and even earlier, why the soft and slender tendrils can bear heavy loads such as the self-weight of a plant or additional load caused by rain remains elusive. In this paper, we take towel gourd tendrils as an example and investigate the macroscopic and microscopic mechanical behaviors of tendrils through experiments and simulations. Our study indicates that the tendril filament exhibits rubber-like hyperelastic behaviors and can particularly endure large elongation, which is mainly attributed to the superelasticity of the cellulose fibril helix contained in the cell wall. Combination of the tendril helical structure with dual chirality or chiral perversion at a macroscale and a cellulose filament helix at a subcellular level creates superior elasticity for biological species relying on support and climbing. This study provides deep insight into the structure-property relationship of climbing tendrils, and the relationship is useful for the bioinspired design of composite systems with superior elasticity.

关键词： Climbing tendril Mechanical behaviors Structure-property relationship Large elongation

MODELING OF STATIC RECRySTALLIZATION KINETICS OF Nb-BEARING STEELS

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Acta Metallurgica Sinica(English Letters) 2006年第4期19卷 271-278页

作者： L.q. Ma Z.y. liu S.H. Jiao X.q. yuan D. Wu The State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110004 China Institute of Research and Development Baosteel Co. Ltd Shanghai 201900 China

By using isothermal double hit compression tests and applying the 2% offset method, a new model was developed to predict the microstructural evolution of Nb-bearing steels at temperatures above and below the start temperature of strain-induced precipitation （Tp）. The Tp was developed as a function of true strain, initial austenite grain size and the Nb content. The activation energy of static recrystallization （qrex） was expressed as a function of the content of different alloy elements. It was found that Nb played the most important role in increasing the value of qrex, The microstructural observations and measurements confirmed the validity of the model developed in the present investigation.

关键词： Nb-bearing steel static recrystallization Tp (start temperature of strain-induced precipitation) activation energy

Soft computing approach for prediction of surface settlement induced by earth pressure balance shield tunneling

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Underground Space 2021年第4期6卷 353-363页

作者： W.G.Zhang H.R.Li C.Z.Wu y.q.Li Z.q.liu H.L.liu Key Laboratory of New Technology for Construction of Cities in Mountain Area Chongqing UniversityChongqing 400045China National Joint Engineering Research Center of Geohazards Prevention in the Reservoir Areas Chongqing UniversityChongqing 400045China School of Civil Engineering Chongqing UniversityChongqing 400045China Norwegian Geotechnical Institute(NGI) Sognsveien 720855 OsloNorway

Estimating surface settlement induced by excavation construction is an indispensable task in tunneling,particularly for earth pressure balance(EPB)shield *** this study,predictive models for assessing surface settlement caused by EPB tunneling were established based on extreme gradient boosting(XGBoost),artificial neural network,support vector machine,and multivariate adaptive regression *** from three tunnel construction projects in Singapore were used,with main input parameters of cover depth,advance rate,earth pressure,mean standard penetration test(SPT)value above crown level,mean tunnel SPT value,mean moisture content,mean soil elastic modulus,and grout *** performances of these soft computing models were evaluated by comparing predicted deformation with measured *** demonstrate the acceptable accuracy of the model in predicting ground settlement,while XGBoost demonstrates a slightly higher *** addition,the ensemble method of XGBoost is more computationally efficient and can be used as a reliable alternative in solving multivariate nonlinear geo-engineering problems.

关键词： EPB Surface settlement Soft computing XGBoost Multivariate adaptive regression spline

Molecular Arrangement of a Bolaamphiphilic Anthrancene Derivative in Langmuir-Blodgett Film

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Chinese Chemical Letters 2001年第12期12卷 1105-1108页

作者： Lu, q liu, MH Chinese Acad Sci Lab Colloid & Interface Sci Ctr Mol Sci Inst Chem Beijing 100080 Peoples R China

This paper reports the molecular assembly in the LB film of a novel bolaamphiphilic anthracene derivative (BISANS) in comparison with that of one-headed amphiphilic anthracene derivative (ANS). While ANS formed a stretched monolayer at the air/water interface, BISANS underwent aggregation to form crystal film on the water surface. Both of the H-aggregates and J-aggregates exist in the transferred LB films of bolaamphiphilic BISANS, only J-aggregates formed in the LB film of ANS.

关键词： bolaamphiphile air/water interface stretched monolayer

IMPROVEMENT OF DISPERSION ABILITy OF NANOMETER PARTICLES By MEANS OF PLASMA POLyMERIZATION

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Acta Metallurgica Sinica(English Letters) 2002年第1期15卷 73-76页

作者： G.q. Zhang X.G. Guo y.M. liu y.J. Ge Beijing Inst. of Printing Beijing 102600 China

In order to find a new way to improve the dispersion ability of nanometer material, an investigation on preparation of thin film with low surface energy on the surface of nanometer material by means of plasma polymerization has been done. Some physical behaviors and chemical constitution of prepared film as well as the influence of polymerized film on nanometer material were tested. All the experimental results showed that this is a possible way to improve the dispersion ability of nanometer materials.

关键词： plasma polymerization nanometer material

Rational design of AgGaS/ZnS/ZnS quantum dots with a near-unity photoluminescence quantum yield via double shelling scheme

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Journal of Materials Science & Technology 2024年第2期169卷 235-242页

作者： H.X.Lu H.liu Z.Z.Fu y.y.Chen H.q.Dai Z.Hu W.L.Zhang R.q.Guo Institute for Electric Light Sources School of Information Science and TechnologyFudan UniversityShanghai 200433China Institute of Future Lighting Academy for Engineering and TechnologyFudan UniversityShanghai 200433China yiwu Research Institute of Fudan University YiwuZhejiang 322000China Zhongshan-Fudan Joint Innovation Center Zhongshan 528437China

In this study,a two-step method was used to synthesize highly luminescent AgGaS/ZnS/ZnS quantum dots(qDs).In the first step,an inner ZnS shell was formed via a one-pot method,which resulted in a smaller lattice mismatch between the AgGaS core and the outer ZnS shell,thereby facilitating the formation of a thick outer *** the two-step shelling process,the synthesized AgGaS/ZnS/ZnS qDs showed an excellent photoluminescence quantum yield(PLqy)of 96.4%with a peak wavelength of 508 nm,repre-senting the highest PLqy reported thus far for AgGaS ***,the effect of halogen ions in Zn precursors on the shelling process was *** was proposed that the capacity of halogen ions to coordinate with the qDs influenced the balance between Zn cation diffusion and ZnS shelling ***,the ZnS shelling reaction was dominant when ZnCl_(2)was employed,while Zn cation diffusion was the dominant process under the I^(−)-rich *** work provides insights into the interfacial restructuring during the ZnS shelling and offers a clear map for the tailored synthesis of core/shell qDs.

关键词： AgGaS quantum dots Photoluminescence Core/shell Alloyed core/shell interface

ON THE BURN RESISTANCE OF Ti-35V-15Cr-0.05C TITANIUM ALLOy

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Acta Metallurgica Sinica(English Letters) 1998年第3期11卷 202-206页

作者： G.P.Li D.Li y.y.liu q.J.Wang S.X.Guan q.C.Li Inst of Metal Research The Chinese Acad of Sciences Shenyang China

The Ti-35V-15Cr-0.05C (wt% is a new nonburning titanium alloy. The test for alloy combustibility was carried out by using CO2 laser. A 430 watt and 6mm diameter laser spot impinges directly on the sample within normal atmospheric pressure and temperature. The results show that the ignition time of the nonburning titanium alloy is the longest in the eight examined titanium alloys, and is 3.5 times that of TC4 alloy. The ignition tempeerature of the nonburning alloy is 2991° C, and is higher than that of TC4 alloy by 1976°C. On the condition of high tempeerature and rich oxygen,the surface of alloy forms a melting layer which plays roles of oxygen insulation, heat insulation and burning products insulation. This is the mechanism of combustion resistance.

关键词： Ti-35V-15Cr-0.05C (wt%) nonburning titanium alloy combustion resistance