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Effect of Process Factors on Microstructure of Semisolid Continuous Casting Billets

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International Journal of Minerals,Metallurgy and Materials 2000年第4期14卷 242-245页

作者： Shuming Xing, Qijie Zhai, Hanqi Hu ( Department of mechanical engineering, Tsinghua University, Beijing 100084, {2. school of Material science and engineering, Shanghai University, Shanghai 2.0072. {2. Material science and engineering school, Univer Department of mechanical engineering Tsinghua University Beijing 100084 China school of Material science and {2. Shanghai University Shanghai 200072 China Material science and engineering {2. University of Science and Technology Beijing Beijing 100083 China

Semisolid continuous casting (SSCC) is a new technology to produce billets for semisolid metal forming (SSMF). The effect of process factors, such as pouring temperature, stirring rate, preheating temperature and thermal conductivity of stirring chamber, on the microstructure of SSCC billets was studied by means of the factorial experimental method. The results show that the microstructure of SSCC billets can be controlled by the above-mentioned four process factors. In order to obtain fine and rounded granular grains in an SSCC billet, the pouring temperature, preheating temperature and stirring rate should be kept in a moderate range, and the thermal conductivity of stirring chamber should be high. The regression equations with the process factors connecting the microstructure was also set up based on experimental data.

关键词： semisolid metal continuous casting process factors microstructure Metallurgy

Structure and mechanical Properties of Ni-based Porous Superalloy

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Journal of Wuhan University of technology(Materials science) 2010年第1期25卷 73-77页

作者：米国发 school of Materials science and {2. Henan Polytechnic University

The porous superalloy materials with hollow spherical and oriented linear pores were fabricated by means of powder metallurgy using Ni-based superalloy powders. Structure observation revealed that the pores of the porous material exhibited uniform distribution and the pores were of the same size in principle. The sintering necks created between adjacent particles on metal skeleton after sintering. The porosity of the porous material increased with increasing the addition of pore forming agent, and the hollow spherical porous material with a porosity of 81.62. were obtained when the addition of pore forming agent was 40%. The compression test indicated that this kind of materials possesses excellent energy absorption capability, and the compression resistance decreased with the increasing of porosity and pore size.

关键词： porous superalloy powder metallurgy hollow spherical pores oriented linear pores

Effect of powder mixing process on the microstructure and thermal conductivity of Al/diamond composites fabricated by spark plasma sintering

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Rare Metals 2010年第1期29卷 86-91页

作者： CHU Ke, JIA Chengchang, LIANG Xuebing, and CHEN Hui school of Materials science and {2., University of science and technology Beijing, Beijing 100083, china school of Materials science and {2. University of Science and Technology Beijing

Two powder mixing processes, mechanical mixing （MM） and mechanical alloying （MA）, were used to prepare mixed Al/diamond powders, which were subsequently consolidated using spark plasma sintering （SPS） to produce bulk Al/diamond composites. The effects of the powder mixing process on the morphologies of the mixed powders, the microstructure and the thermal conductivity of the composites were investigated. The results show that the powder mixing process can significantly affect the microstructure and the thermal conductivity of the composites. Agglomerations of the particles occurred in mixed powders using MM for 30 min, which led to high pore content and weak interfacial bonding in the composites and resulted in low relative density and low thermal conductivity for the composites. Mixed powders of homogeneous distribution of diamond particles could be obtained using MA for 10 min and MM for 2.h. The composite prepared through MA indicated a high relative density but low thermal conductivity due to its defects, such as damaged particles, Fe impurity, and local interfacial debonding, which were mainly introduced in the MA process. In contrast, the composite made by MM for 2.h demonstrated high relative density and an excellent thermal conductivity of 32. W.m^-1.K^-1, owing to its having few defects and strong inter-facial bonding.

关键词： metal matrix composites thermal properties sintering powder mixing

Solving Capacitated Vehicle Routing Problem Based on Improved Genetic Algorithm

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Solving Capacitated Vehicle Routing Problem Based on Improve...

s-ordering operator expansions of quantum-mechanical fundamental representations and their applications

2.11 Chinese Control and Decision Conference（CCDC）

作者： Wang Jie-sheng is with the school of Electronic and Information engineering,{2. University of science & technology,anshan,114044,china Liu Chang is with the school of Electronic and Information engineering,{2. University of science & technology,anshan,114044,china.Zhang Ying is with the school of Electronic and Information engineering,{2. University of science & technology,anshan,114044,china

Aiming at the capacitated vehicle routing problem （CVRP） in the matter stream delivery field,an improved genetic algorithm （GA） based on local mutation operator is *** layers chromosome coding scheme is designed which can improve initial *** coding method can insure that the sub-routing is effective to satiety the vehicle capacitated *** improved measures have important significance to depress procedural intricacy degree,advance convergence of algorithm velocity and algorithmic local search *** simulation experiment results show the improved genetic algorithm compared with BGA can achieve better optimization results and has better efficiency to solve CVRP.

关键词： Capability Vehicle Routing Problem Genetic Algorithm Two Layers Chromosome Local Mutation

来源： cnki会议评论

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science china(Physics,Mechanics & Astronomy) 2011年第12期54卷 2150-2154页

作者： FAN HongYi 1,3 , XU YeJun 2.& YUAN HongChun 3,4 1 Department of Materials science and engineering, University of science and technology of china, Hefei 2.002., china 2.Department of Physics Electronic and engineering, Chizhou University, Chizhou 2.7000, china 3 Department of Physics, Shanghai Jiao Tong University, Shanghai 2.0030, china 4 College of Optoelectronic engineering, Changzhou Institute of technology, Changzhou 2.3002. china 1. Department of Materials science and engineering University of Science and Technology of China Hefei 230026 China3. Department of Physics Shanghai Jiao Tong University Shanghai 200030 China2. Department of Physics Electronic and Engineering Chizhou University Chizhou 247000 China4. College of Optoelectronic Engineering Changzhou Institute of Technology Changzhou 213002 China

We show that the quantum-mechanical fundamental representations, say, the coordinate representation, the coherent state representation, the Fan-Klauder entangled state representation can be recast into s-ordering operator expansion, which is elegant in form and has many applications in deriving new operator identities. This demonstrates that Dirac's symbolic method can be merged into Newton-Leibniz integration theory in a broad way.

关键词： s-ordering operator expansion operator identities quantum mechanical representation

Wafer level bonding using localized radio-frequency induction heating

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science china(Technological sciences) 2010年第5期53卷 1252-1257页

作者： CHEN MingXiang1,2.LIU WenMing1,2.XI YanYan1,2.LIN ChangYong1,2.& LIU Sheng1,2.1 school of mechanical {2. & engineering,Huazhong University of {2. and technology,Wuhan 430074,china 2.Division of MOEMS,Wuhan National Laboratory for Optoelectronics,Wuhan 430074,china 1. school of mechanical {2. & engineering Huazhong University of Science and Technology Wuhan 430074 China2. Division of MOEMS Wuhan National Laboratory for Optoelectronics Wuhan 430074 China

A wafer level bonding technique by localized induction heating has been developed and demonstrated in this paper.A suitable fabrication process scheme has also been established for the localized induction heating and *** takes only about 2. seconds to complete the bonding *** temperatures of solder loops and the central area of solder loops are above 300°C and below 70°C,*** to the solder reflow,robust and hermetic glass wafer bonding is accomplished,and the average tensile strength is 6.42.***-heated or over-heated bonding has been found to result in cracks at bonding interfaces and sputtering layer,which degrades the bonding qualities.

关键词： wafer bonding induction heating MEMS MEMS packaging

Elastic Modulus of 304 Stainless Steel Coating by Cold Gas Dynamic Spraying

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Journal of Iron and Steel Research International 2012年第3期19卷 73-78页

作者： HAN Wei1, MENG Xian-ming1, ZHANG Jun-bao2. ZHAO Jie1 (1. school of Material science and {2., Dalian University of technology, Dalian 116085, liaoning, china 2. Baoshan Iron and Steel Company Limited, Baosteel Research Institute, Shanghai 2.1900, china) [a] school of Material science and {2. Dalian University of Technology Dalian 116085 Liaoning China [b] Baoshan Iron and Steel Company Limited Baosteel Research Institute Shanghai 201900 China

304 stainless steel coating was deposited on the IF steel substrate by cold gas dynamic spraying （CGDS）, and the elastic modulus of the 304 stainless steel coating was studied. The elastic modulus of cold sprayed 304 stain- less steel coating was measured using the three-point bend testing and the compound beam theory, and the other me- chanic parameters （such as the equivalent flexural rigidity and the moment of inertia of area） of the coatings were also calculated using this compound beam theory. It is found that the calculated results using the above methods are accu- rate and reliable. The elastic modulus value of the cold sprayed 304 stainless steel coating is 1. 179 X 105 MPa, and it is slightly lower than the 304 stainless steel plate （about 2.X 105 MPa）. It indicates that the elastic modulus of the cold sprayed coatings was quite different from the comparable bulk materials. The main reason is that the pores and other defects are existed in the coatings, and the elastic modulus of the coatings also depends on varies parameters such as the feed stock particle size, porosity, and processing parameters.

关键词： cold gas dynamic spraying 304 stainless steel coating three-point bend testing compound beam theory elastic modulus

Deformation Uniformity of Cold-Rolled Q2.5 Steel Rebar by FEM in Bending and Rolling Processes

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Journal of Iron and Steel Research International 2012年第8期19卷 37-42页

作者： SUI Feng-li1, CHEN Qi-wei1, ZHU Guo-hui1, LIU Bao-dong2.(1. Anhui Key Laboratory of Materials and Processing, school of Materials science and {2., Anhui University of technology, Maanshan 2.3002. Anhui, china 2. Dongyang Steel Making Co Ltd, Shenyang 11002., liaoning, china) [a] Anhui Key Laboratory of Materials and Processing School of Materials Science and Engineering Anhui University of Technology Maanshan 243002 Anhui China [b] Dongyang Steel Making Co Ltd Shenyang 110026 Liaoning China

An analytic model based on ANSYS/LS-DYNA has been developed on the cold rolling process for Q2.5 steel rebar with 12.mm in diameter. The elastic-plastic finite element method (FEM) and the cold deformation resistance model of Q2.5 steel were adopted in this model. Deformation uniformity of the final product has been analyzed using this model. The results indicate that the uniformity of the final product is obtained only as the centerline of the bending rolls is vertical to the centerline of the driven roll and parallel to the centerline of the drive roll in the whole rolling process. Besides, the number of the bending rolls must even realize the continuous bending and reverse bending process. Also, the number of the bending rolls must match the deformation degree of the workpiece in the cold rolling process. The validity of this finite element model was verified by the size and distribution of grains from the billet to the rebar in a practical cold rolling process.

关键词： deformation uniformity Q2.5 steel rebar finite element method cold rolling mechanical descaling

Microstructure Evolution of Semi-solid Processed Hyper-eutectic Al-30%Si Alloy

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International Journal of Minerals,Metallurgy and Materials 1999年第4期13卷 259-261页

作者： Yanjun Li Weimin Mao Xueyou Zhong(Material science and engineering {2., University of science and technology Beijing, Beijing 100083, china) Material science and engineering {2. University of Science and Technology Beijing Beijing 100083 China

An investigation was made on the influences of mechanical stirring on microstructure of hyper-eutectic Al-30%Si alloy (inmass fraction) during solidification. The primary Si crystals formed in the alloy melt were gradually changed from elongated platelets tonear-spherical shapes by mechanical stirring. The spheroidization of primary St crystals occurs by the mechanism of bending and fractureof Si platelets, wear and collision between Si crystals, and coalescence of small Si particles. The influence of under-cooling and coolingrate of the alloy melt on primary Si crystals of semi-solid processed alloys is investigated as well. The increase of under-cooling andcooling rate decreases the size of primary Si crystals.

关键词： semi-solid state process solidification structure mechanical stirring hyper-eutectic Al-Si alloy