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AN IN SITU SURFACE COMPOSITE AND GRADIENT MATERIAL OF Al-Si ALLOY PRODUCED BY ELECTROMAGNETIC FORCE

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Acta Metallurgica Sinica(English Letters) 2001年第5期14卷 335-340页

作者： Z.M. Xu, T.X. Li, Z.L. Zhu and Y.H. Zhou school of Materials science and engineering,{3., shanghai 20003., china Sch. of Mat. Sci. and Eng. Shanghai Jiaotong Univ. Shanghai 200030 China

Because of the different conductivities between the primary phase (low electric conduc tivity) and the metal melt, electromagnetic force scarcely acts on the primary phase. Thus, an electromagnetic repulsive force applied by the metal melt exerts on the pri mary phase when the movement of the melt in the direction of electromagnetic force is limited. As a result, the repulsive force exerts on the primary phase to push them to move in the direction opposite to that of the electromagnetic force when the metal melt with primary phase solidifies under an electromagnetic force field. Based on this, a new method for production of in situ surface composite and gradient material by electromagnetic force is proposed. An in situ primary Si reinforced surface composite of Al-15wt%Si alloy and gradient material of Al-l9wt%Si alloy were produced by this method. The microhardness of the primary Si is HV13.0. The reinforced phase size is in the range from 40μm to 100μm. The wear resistance of Al-Si alloy gradient material can be more greatly increased than that of their matrix material.

关键词： Al-Si alloy electromagnetic force in situ surface composite gradient material

Physical Simulation of Nonmetallic Particle Movement in Al Melt under Electromagnetic Field

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Journal of Materials science & Technology 2001年第4期17卷 463-465页

作者： Tianxiao LI, Zhenming XU,Baode SUN,Da SHU and Yaohe ZHOU school of Materials science and engineering, {3. jiaotong university, shanghai 20003., china shanghai jiao tong Univ Sch Mat Sci & Engn Shanghai 200030 Peoples R China

Physical simulation is used to study the movement of nonmetallic particles in Al melt in electro- magnetic field. It is found that the terminal velocity of particles in different Reynolds number range has different functions. By confirming drag force coefficient of nonmetallic particles with Reynolds number in the range of 0.2-10 and 10-25 respectively, two functions of terminal ve- locity for spherical nonmetallic particles have been got accordingly, which provide a theoretical basis for separating nonmetallic inclusions from Al melt in electromagnetic field.

关键词： Al Physical Simulation of Nonmetallic Particle Movement in Al Melt under Electromagnetic Field Simulation

Nucleation Mechanism for Bainite

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Journal of Materials science & Technology 2002年第1期18卷 1-2页

作者： Xi ZHANG, Xuejun JIN and T.Y.Hsu(Xu Zuyao)school of Materials science and engineering,{3., shanghai 20003., china [ Manuscript received October 8, 2001] shanghai jiao tong Univ Sch Mat Sci & Engn Shanghai 200030 Peoples R China

Based on the experimental results that solute-depleted zone was observed in Cu-28Zn-4AI (mass fraction) at 523.K, AG is calculated as a positive according to the thermodynamic criteria for the spinodal decomposition of a ternary systems. So, the solute-depleted zone cannot be formed by spinodal decomposition. Dislocation density required by the formation of solute-depleted zone is estimated greater than 7.89×109 cm-2, according to the segregation of solute atoms around dislocations, which is not consistent with the practical situation for the alloy at 523.K. Associated with the internal friction experimental fact that internal friction peaks appear within the incubation for bainitic transformation in Cu-Zn-AI alloy, the equilibrium temperature, TO, is evaluated as 43. K for solute-depleted Cu-25Zn-3.4AI, which is lower than the experimental temperature 523.K. Thus, nucleation by shear mechanism is impossible in this circumstance. Therefore, it is concluded that, like bainite in steels and Ag-Cd, bainite in Cu-Zn-AI alloys nucleates by diffusional mechanism, just implied by the experimental existence of solute-depleted zone.

关键词： Bainitic transformation Prebainitic phenomenon Solute-depleted zone Diffusion Nucleation

Strain Softening and Hardening Behavior in AZ61 Magnesium Alloy

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Journal of Materials science & Technology 2004年第6期20卷 691-693页

作者： Haitao ZHOU, Liufa LIU, Qudong WANG, Da LU, Xiaoqin ZENG and Wenjiang DINGNational engineering Research Center of Light Alloys Net Forming, school of Materials science and engineering, shanghai jiao tong university, shanghai 20003., china Ctr. of Light Alloys Net Forming Sch. of Mat. Sci. and Eng. Shanghai Jiaotong Univ. Shanghai 200030 China

The deformation behavior of AZ61 Mg alloy during hot deformation has been investigated in wide temperature and strain rate range by a Gleeble simulator. Specimens are deformed in compression in the temperature range of 523.673.K and at strain rates of 0.001-1 s-1. It is found that the flow curves exhibit a peak and then decrease towards steady-state of classical DRX, which decrease with rising temperature and decreasing strain rate. The deformation behavior of the specimens can be attributed to the occurrence of strain hardening and softening. As stress decreases, the strain hardening rate declines at a fast rate when temperature rises or strain rate decreases. The shapes of θ-σ curves indicate some important features such as subgrain formation, the criticai stress, the peak stress and steady stress. The onset of DRX can be determined by the point of inflection on θ-σ or Inθ-σ curves.

关键词： AZ61 Mg alloy Recrystallization Strain hardening and softening

SEM in-situ Fracture Observation and the Reinforcing Effect of Composite SiC_p/ZA22

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Journal of Materials science & Technology 2001年第6期17卷 649-652页

作者： Jun WANG, Baode SUN and Yaohe ZHOU school of Materials science and engineering, {3. jiaotong university, shanghai 20003., china Lining ZHANG and Feng CHEN Department of Materials science and engineering, Southeast university, shanghai jiao tong Univ Sch Mat Sci & Engn Shanghai 200030 Peoples R China SE Univ Dept Mat Sci & Engn Nanjing 210096 Peoples R China

The strengthening effect of a Zn alloy reinforced by SiC particulate was examined. Based on the results of SEM in-situ fracture observation and stress field analysis by finite element method, it is believed that the r... 详细信息

关键词： SiC SEM in-situ Fracture Observation and the Reinforcing Effect of Composite SiC_p/ZA22

Effect of Cold Rolling on Microstructure and Mechanical Properties of AISI 3.1LN Metastable Austenitic Stainless Steels

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Journal of Iron and Steel Research International 2012年第10期19卷 59-63页

作者： HUANG Jun-xia1, YE Xiao-ning1, XU Zhou2 (1. shanghai Baosteel Research Institute, shanghai 20043., china 2. {3. of Material science and engineering, shanghai jiao tong university, shanghai 200240, china) [a] shanghai Baosteel Research Institute Shanghai 200431 China [b] school of Material science and engineering Shanghai Jiao Tong University Shanghai 200240 China

The microstructure and mechanical properties evolution of AISI 3.1LN metastable austenitic stainless steels during cold rolling were investigated. A wide range of cold thickness reduction (10%-80%) was carried out in a four-high rolling mill at ambient temperature. The X-ray and Feritscope MP3. were used to identify the strain-induced α′-martensite phase and its volume fraction, respectively. The microstructure was observed by optical micrograph and the mechanical properties were determined by tensile tests and microhardness. The results show that the strain-induced α′-martensite nucleated at the shear bands intersections and the growth of α′-martensite occurred by the repeated nucleation of new embryos. The volume fraction of strain-induced α′-martensite increased with increasing the cold rolling reduction. In addition, the percentage increased in the tensile strength is the same as that of hardness. The ratio between the average tensile strength and the average microhardness was found to range between 2.82 and 3.17.

关键词： metastable austenitic stainless steel cold rolling reduction strength

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

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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 23.026, china 2 Department of Physics Electronic and engineering, Chizhou university, Chizhou 247000, china 3.Department of Physics, shanghai jiao tong university, shanghai 20003., china 4 College of Optoelectronic engineering, Changzhou Institute of Technology, Changzhou 213.02, 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

Preparation,Characterization and Visible Light Photocatalytic Activity of Nitrogen-doped TiO_2

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Journal of Wuhan university of Technology(Materials science) 2006年第4期21卷 71-77页

作者：王正鹏 school of environmental science and {3. Shanghai Jiao Tong UniversityShanghai 200240China

The N-doped TiO2 polycrystalline powder was synthesized through calcining the hydrolysis prodact of tetra-butyl titanate with ammonia. The photocatalytic activity of N-doped TiO2 powder with anatase phone calcined at 400℃ was 2.7 times higher than that of Degussa P25 for phenol decomposition under visible light. All samples had mesoporoas structures. X- ray photoelectron spectroscopy confirmed that a trace amount of N atoms remained in the anatase polycrystaUine TiO2 powder when calcined at 400 ℃ as substitutional atoms at the oxygen sites. UV-Vis and EPR analyses indicated that oxygen vacancy states were created during the course of N-doped TiO2 powder formation. It is considered that substitutional N atoms, oxygen vacancy, states, large BET surface areas and mesoporoas structure are important facwrs for the N-doped photocatalyst to present a high vis-activity.

关键词： photocatalyst visible Light nitrogen-doped TiO2 phenol

Study on an Explosion Treated Steel Weld Metal with Prepared Crack

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Journal of Materials science & Technology 2001年第3期17卷 385-387页

作者： Xiaonan GUO and Xin LONG school of Materials science and engineering,{3., shanghai 20003., china Huaining CHEN and Liangshan CHEN Institute of Metal Research, Chinese Academy of sciences, Shenyang 110016, china Guangjun GAI Depa jiao tong Univ Sch Mat Sci & Engn Welding Inst Shanghai 200030 Peoples R China Chinese Acad Sci Met Res Inst Shenyang 110016 Peoples R China SW jiaotong Univ Dept Mat Sci & Engn Chengdu 610031 Peoples R China

A softening zone with recrystallized grain around the prepared crack tip in the shock waves treated C-Mn steel weld metal was observed. It is suggested that a dynamic recovery occurred around the prepared crack tip even at a low explosion pressure (5 GPa) because of the stress and strain concentration at the crack tip when shock waves pass through. This result supports the previous work on the improved mechanical properties of a shock treated welded joint with residual crack from the viewpoint of microstructure.

关键词： Study on an Explosion Treated Steel Weld Metal with Prepared Crack very high Chen