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Journal of Materials Science & Technology 2021年第30期89卷 158-166页

作者： l.l.li z.B.Wang S.Y.He Y.G.zheng CAS Key laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Department of Physics Southern University of Science and TechnologyGuangdong 518055China

The correlation between depassivation and repassivation processes,which is significant in erosioncorrosion,was quantitatively investigated by single particle impingement tests at various flow velocities and impact *** results show that both repassivation and depassivation processes are associated with the kinetic energy of solid particle,and demonstrate that the repassivation is retarded by *** phenomenon probably results from the depassivation-induced microstructure *** this basis,the dependence of critical flow velocity(CFV)for erosion-corrosion on the solid particle concentration and diameter is further theoretically predicted and experimentally ***,the crucial role of depassivation-repassivation in CFV phenomenon is further highlighted.

关键词： Erosion-corrosion Stainless steel Depassivation-repassivation Single particle impact Passive film

MECHANISM AND KINETICS OF TRANSFORMATION OF AlUMINA INClUSIONS BY CAlCIUM TREATMENT

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Acta Metallurgica Sinica(English letters) 2006年第1期19卷 1-8页

作者： z.J. Han l. liu M. lind l. Holappa Central Iron and Steel Research Institute Beijing 100081 China laboratory of Metallurgy Helsinki University of Technology P.O. Box 6200Espoo 02015 Finland

The basic mechanism and kinetics of the transformation process of alumina inclusions in steel was reported when calcium introduced into the steel by wire feeding orpowder injection. To clarify the mechanisms model, experiments were performed by studying reactions between AltOs and CaO in a laboratory furnace and by performing calcium treatments in an 8kg induction furnace for Al deoxidised melt. The phases formed during the reaction between Al2O3 and CaO were examined by SEM-EDS （scanning electron microscope-energy dispersive spectrometer）, and the reaction sequence of Al2O3=〉 CA6=〉 CA2 =〉 CA =〉 CAx（l） was discussed in term of the experimental observations. The kinetics of the reaction of calcium with alumina inclusions were simulated by immersing alumina plates in a Ca treated steel melt in the induction furnace. Results were compared with observations of real inclusion transformation. A kinetic model was proposed based on the results.

关键词： mechanism kinetics alumina inclusion transformation

SURFACE COMPOSITE GEAR AND PIPE MADE BY SEPARATED EUTECTIC TECHNOlOGY

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Acta Metallurgica Sinica(English letters) 2000年第3期13卷 883-887页

作者： Cao, z.Q. Piao, l.Y. zhang, X.G. li, z. jin, J.z. Dalian Univ of Technology Dalian China

It is found that the anomalous eutectics can be separated on macroscopic scale by flow caused by electromagnetic stirring, and the separated phase is the leading faceted phase with the solution entropy over 23 J/(mol·K). By using this technology, a new kind of composite pipe and gear with good abrasive properties were made without adding any reinforced particles. Emphases were paid on the researches about formation mechanism of separated eutectic and abrasive property of the composite pipe or gear. The result shows that the entropy of solution controlling the eutectic microstructure is also valid and useful as a criterion of separated eutectic, and the kind and its chemical scope of the off-eutectic used to make composite can be calculated according to this theory.

关键词： Binary alloys Eutectics Gears Microstructure Pipe Rotational flow Separators Solidification

Use of compositional and combinatorial nanomaterial libraries for biological studies

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Science Bulletin 2016年第10期61卷 755-771页

作者： zhaoxia ji Center for Environmental Implications of Nanotechnology California Nano Systems Institute University of California

Abstract The rapid development and production of nanomaterials has created some concerns about their potential hazard on the environment, human health and safety. However, since the list of materials that may gen- erate such concerns is very long, it is impossible to test them all. It is therefore usually recommended to use some small compositional nanomaterial libraries to perform ini- tial toxicity screening, based on which combinatorial libraries are then introduced for more in-depth studies. All nanomaterials in the compositional and combinatorial libraries must be rigorously characterized before any bio- logical studies. In this review, several major categories of physicochemical properties that must be characterized are discussed, along with different analytical techniques that are commonly used. Some case studies from the University of California Center for Environmental Implications of Nanotechnology are also chosen to demonstrate the effec- tive use of compositional and combinatorial nanomaterials libraries to identify the role of some key physicochemical properties and to establish true quantitative structure-ac- tivity relationships. Examples on how to use the knowledge generated from those studies to design safer nanomaterials for improved biological applications are also presented.

关键词： Nanomaterial Physicochemical property Characterization Nanotechnology Toxicity Compositional library Combinatoriallibrary

Magneto optics and time resolved terahertz spectrocopy

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Chinese Physics B 2018年第7期27卷 112-119页

作者： T Dong z G Chen N l Wang International Center for Quantum Materials School of PhysicsPeking UniversityBeijing 100871China Institute of Physics Chinese Academy of SciencesBeijing 100190China

Exploring, manipulating, and understanding new exotic quantum phenomena in condensed-matter systems have gen- erated great interest in the scientific community. Static and time resolved optical spectroscopies after photoexcitations are important experimental tools for probing charge dynamics and quasiparticle excitations in quantum materials. In Syner- getic Extreme Condition User Facility （SECUF）, we shall construct magneto-infrared and terahertz measurement systems and develop a number of ultrafast femtosecond laser based systems, including intense near to mid-infrared pump terahertz probe. In this article, we shall describe several systems to be constructed and developed in the facilities, then present some examples explaining the application of magneto optics and time resolved spectroscopy techniques.

关键词： magneto-optics infrared spectroscopy mid-infrared pump terahertz probe

Mechanical Properties of a low-thermal-expansion Aluminum/Silicon Composite Produced by Powder Metallurgy

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Journal of Materials Science & Technology 2014年第4期30卷 417-422页

作者： Y.Q.liu S.H.Wei J.z.Fan z.l.Ma T.zuo National Engineering & Technology Research Center for Nonferrous Metal Matrix Composites Beijing General Research Institute for Nonferrous Metals

AI matrix composite containing high volume fraction silicon has been promising candidate for lightweight and low-thermal-expansion components. Whereas, optimization of its mechanical properties still is an open challenge. In this article, a flexile powder metallurgy processing was used to produce a fully dense AI-4.0Cu （wt%） alloy composite reinforced with 65 vol.% Si particles. In this composite, Si particles were homogenously distributed, and the particle size was refined to the range of 3-15 μm. Tensile and flexural strength of the composite were 282 and 455 MPa, respectively, about 100% and 50% higher than the best properties reported in literature. The measured fracture toughness of the composite was 4.90 MPa m1/2. The improved strength of 65%Si/AI was attributed to the optimized particle characteristics and matrix properties. This investigation is expected to provide a primary understanding of the mechanical behaviors of Si/AI composites, and also promote the structural applications of this low-thermal-expansion material.

关键词： Aluminum matrix composite Powder metallurgy Mechanical properties Coefficient of thermal expansion Fracture

Effect of Yttrium Addition on Microstructural Characteristics and Superplastic Behavior of Friction Stir Processed zK60 Alloy

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Journal of Materials Science & Technology 2013年第12期29卷 1116-1122页

作者： z.A.luo G.M.Xie z.Y.Ma G.l.Wang G.D.Wang State Key laboratory of Rolling and Automation Northeastern University Shenyang National laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences

As-extruded zK60 and zK60-Y magnesium alloy plates were successfully processed via friction stir processing （FSP） at a tool rotation rate of 1600 r/rain and a traverse speed of 200 mm/min. FSP resulted in the formation of equiaxed recrystallized microstructures with the average grain sizes of ,-8.5 and -4.7 μm in the zK60 and zK60-Y alloys, respectively. Moreover, FSP broke and dispersed the Mgzn2 and W-phase （Mg3zn3Y2） particles and dissolved Mgzn2 phase in the FSP zK60 alloy. With the addition of rare earth element yttrium （Y） into the zK60 alloy, the ratio of the high angle grain boundaries （HAGBs） in the FSP alloys increased from 64% to 90%, and a certain amount of twins appeared in the FSP zK60-Y alloy. The maximum elongation of 1200% and optimum strain rate of 3 X 10-3 s-1 achieved at 450 °C in the FSP zK60-Y alloy were substantially higher than those of the FSP zK60 alloy. This is attributed to the fine grains with high ratio of HAGBs and the distribution of a large number of dispersed second phase particles with high thermal stability in the FSP zK60-Y alloy. Grain boundary sliding was identified as the primary deformation mechanism in the FSP zK60 and zK60-Y alloys from the superplastic data analyses and surficial morphology observations.

关键词： Magnesium alloy Friction stir processing Rare earth element Microstructure Superplasticity

Spectral measurements of hypervelocity flow in an expansion tunnel

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Acta Mechanica Sinica 2019年第1期35卷 24-31,I0002页

作者： C.K.Yuan K.zhou Y.F.liu z.M.Hu z.l.jiang State Key laboratory of High-Temperature Gas Dynamic Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering Sciences. University of Chinese Academy of Sciences Beijing 100049China China Academy of Aerospace Aerodynamics Beijing 100074China

Atmospheric reentry vehicles and planetary probes fly through the atmosphere at hypervelocity speed. At such speed, there is a significant proportion of heat load to the vehicle surface due to radiative heating. Accurate prediction needs a good knowledge of the radiation spectrum properties. In this paper, a high-speed camera and spectrograph coupled to an intensified charge-coupled device have bee n impleme nted to inv estigate the rad i at io n flow over a semi-cylinder model. The experiments were carried out in the JF16 expansi on timnel with secondary shock velocity of 7.9 km·s^-1. Results show that the emissio n spectrum comprises several atomic lines and molecular band systems. We give detailed data of the radiation spectrum, shock shape, shock detached distance and radiation intensity varying with space and wavelength. This valuable experimental dataset will be helpful to validate computational fluid dynamics codes and radiation models, which equates to increased prediction accuracy of radiation heating. Also, some suggestions for spectral measurement in hypervelocity flow field were list in the end.

关键词： Spectral measurement Hypervelocity flow Radiation Expansion tunnel

Basic features of the multiscale interaction between tearing modes and slab ion-temperature-gradient modes

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Chinese Physics B 2019年第12期28卷 237-247页

作者： l Wei z X Wang J Q li z Q Hu Y Kishimoto Key laboratory of Materials Modification by laser Ionand Electron Beams(Ministry of Education)School of PhysicsDalian University of TechnologyDalian 116024China Southwestern Institute of Physics Chengdu 610041China Graduate School of Energy Science Kyoto UniversityGokashoUjiKyoto 1-0011Japan

Nonlinear interaction between tearing modes(TM) and slab ion-temperature-gradient(ITG) modes is numerically investigated by using a landau fluid model. It is observed that the energy spectra with respect to wavenumbers become broader during the transition phase from the ITG-dominated stage to TM-dominated stage. Accompanied with the fast growth of the magnetic island, the frequency of TM/ITG with long/short wavelength fluctuations in the electron/ion diamagnetic direction decreases/increases respectively. The decrease of TM frequency is identified to result from the effect of the profile flattening in the vicinity of the magnetic island, while the increase of the frequencies of ITG fluctuations is due to the eigenmode transition of ITG induced by the large scale zonal flow and zonal current related to TM. Roles of zonal current induced by the ITG fluctuations in the instability of TM are also analyzed. Finally, the electromagnetic transport features in the vicinity of the magnetic island are discussed.

关键词： magnetic reconnection tearing modes magnetohydrodynamics drift waves nonlinear phenomena

Numerical simulation of effect of rotational tool with screw on material flow behavior of friction stir welding of Ti6Al4V alloy

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Acta Metallurgica Sinica(English letters) 2012年第5期25卷 365-373页

作者： Shude ji Aili zOU Yumei YUE Guohong l UAN Yanye jiN Fu lI Faculty of Aerospace Engineering Shenyang Aerospace University Shenyang 110136 China Beijing Aeronautical Manufacturing Technology Research Institute Beijing 100024 China

The rotational tool is put forward, which is composed of the one-spiral-flute shoul- der and the rotational pin with screw. Using the turbulent model of the FlUENT software, material plastic flow behavior during the process of friction stir welding of Ti6A14V alloy is researched by the numerical simulation method and then the effect of rotational tool geometry on material flow during the welding process is attained. The results show that the flow direction of the material near the rotational tool is mainly the same as the rotational direction of the tool while the material near tool flows more violently than the other regions. For the tapered rotational pin, the flow velocity of material inside the workpiece decreases with the increase of the distance away from the workpiece surface because of the change of pin diameter. For the rotational tool, the flute added to the shoulder and the screw added to the pin can greatly increase the flow velocity of material during the welding process while the peak value of the flow velocity of material appears on the flute or the screw. Moreover, the rotational tool with the one-spiral-flute shoulder is better than the tool with the concentric- circles-flute shoulder. Decreasing the width of pin screw and increasing the diameter of pin tip are both good for the increase of flow velocity.

关键词： Friction stir welding Titanium alloy Plastic flow Numericalsimulation