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Microstructure and texture evolution of Mg–3Zn–1Al magnesium alloy during large-strain electroplastic rolling

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International Journal of Minerals,Metallurgy and Materials 2015年第4期22卷 411-416页

作者： Yan-bin Jiang Lei Guan Guo-yi Tang bo Cheng da-bo Liu Key Laboratory for Advanced Materials Processing of the Ministry of Education Institute of Advanced Materials and Technology University of Science and Technology Beijing Beijing Institute of Aeronautical Materials Aviation Industry Corporation of China Advanced Materials Institute Graduate School at Shenzhen Tsinghua University

Large-strain deformation by single electroplastic rolling （EPR） was imposed on AZ31 magnesium alloy strips. During EPR at low temperature （150-250℃）, numerous twins formed in the alloy. After EPR at a high temperature （350℃）, the number of twins reduced and some dynamic recrystallization （DRX） grains formed at grain boundaries and twinned regions. The synergic thermal and athermal effects generated by electropulsing, which promoted dislocation motion, induced a few small DRX grains, and ductile bandings were mainly re- sponsible for large-strain deformation during EPR. The inclination angle of the basal pole stemmed from the counterbalance of the inclina- tion direction of the basal pole between the DRX grains and deformed coarse grains.

关键词： magnesium alloys electroplastic rolling microstructure texture recrystallization

Research on Flexural Behavior of Coral Aggregate Reinforced Concrete Beams

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China Ocean Engineering 2018年第5期32卷 593-604页

作者： MA Hai-yan da bo YU Hong-fa WU Zhang-yu Department of Civil Engineering Nanjing University of Aeronautics and Astronautics

Through the flexural behavior test of coral aggregate reinforced concrete beams(CARCB) and ordinary Portland reinforced concrete beams(OPRCB), and based on the parameters of concrete types, concrete strength grades and reinforcement ratios, the crack development, failure mode, midspan deflection and flexural capacity were studied, the relationships of bending moment-midspan deflection, load-longitudinal tensile reinforcement strain, load-maximum crack width were established, and a calculation model for the flexural capacity of CARCB was suggested. The results showed that with the increase in the reinforcement ratio and concrete strength grade, the crack bending moment(Mcr)and ultimate bending moment(Mu) of CARCB gradually increased. The characteristics of CARCB and OPRCB are basically the same. Furthermore, through increasing the concrete strength grade and reinforcement ratio, Mcr/Mu could be increased to delay the cracking of CARCB. As the load increased, crack width(w) would also increase. At the beginning of the loading, w increased slowly. And then it increased rapidly when the load reached to the ultimate load, which then led to beam failure. Meanwhile, with a comprehensive consideration of the effects of steel corrosion on the loss of steel section and the decrease of steel yield strength, a more reasonable calculation model for the flexural capacity of CARCB was proposed.

关键词： coral aggregate reinforced concrete beam flexural behavior steel corrosion reinforcement ratio concrete strength calculation model

Mesoscopic Modeling Approach and Application for Steel Fiber Reinforced Concrete under Dynamic Loading:A Review

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Engineering 2022年第9期16卷 220-238页

作者： Jinhua Zhang Zhangyu Wu Hongfa Yu Haiyan Ma bo da School of Civil Engineering Southeast UniversityNanjing 210096China Department of Civil and Airport Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China Science and Technology on Near-Surface Detection Laboratory Wuxi 214035China College of Harbour Coastal and Offshore EngineeringHohai UniversityNanjing 210098China

Steel fiber reinforced concrete(SFRC)has drawn extensive attention in recent years for its superior mechanical response to dynamic and impact *** on the existing test results,the highstrength steel fibers embedded in a concrete matrix usually play a strong bridging effect to enhance the bonding force between fiber and the matrix,and directly contribute to the improvement of the post-cracking behavior and residual strength of *** gain a better understanding of the action behavior of steel fibers in matrix and further capture the failure mechanism of SFRC under dynamic loads,the mesoscopic modeling approach that assumes SFRC to be composed of different mesoscale phases(i.e.,steel fibers,coarse aggregates,mortar matrix,and interfacial transition zone(ITZ))has been widely employed to simulate the dynamic responses of SFRC material and structural *** paper presents a comprehensive review of the state-of-the-art mesoscopic models and simulations for SFRC under dynamic *** approaches for the SFRC mesoscale model in the simulation works,including steel fiber,coarse aggregate,and the ITZ between them,are reviewed and compared *** material models for different phases and the interaction relationship between fiber and concrete matrix are summarized ***,some example applications for SFRC under dynamic loads(i.e.,compression,tension,and contact blast)simulated using the general mesoscale models are ***,some critical analysis on the current shortcomings of the mesoscale modeling of SFRC is highlighted,which is of great significance for the future investigation and development of SFRC.

关键词： Steel fiber reinforced concrete Mesoscale modeling Dynamic loading Materials model Interfacial characteristic

Calculations of Energy-Loss Function for 26 Materials

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Chinese Journal of Chemical Physics 2016年第6期29卷 663-670,I0001页

作者： Yang Sun Huan Xu bo da Shi-feng Mao Ze-jun Ding HefeiNationalLaboratoryforPhysicalSciencesattheMicroscaleandDepartmentofPhysics UniversityofScienceandTechnologyofChinaHefei230025China

We present a fitting calculation of energy-loss function for 26 bulk materials, including 18 pure elements （Ag, A1, Au, C, Co, Cs, Cu, Er, Fe, Ge, Mg, Mo, Nb, Ni, Pd, Pt, Si, Te） and 8 compounds （AgCl, Al2O3, AlAs, CdS, SiO2, ZnS, ZnSe, ZnTe） for application to surface electron spectroscopy analysis. The experimental energy-loss function, which is derived from measured optical data, is fitted into a finite sum of formula based on the Drude-Lindhard dielectric model. By checking the oscillator strength-sum and perfect- screening-sum rules, we have validated the high accuracy of the fitting results. Further-more, based on the fitted parameters, the simulated reflection electron energy-loss spec- troscopy （REELS） spectrum shows a good agreement with experiment. The calculated fitting parameters of energy loss function are stored in an open and online database at http：//***/ELF/***.

关键词： Energy loss function Dielectric function Optical data

Fabrication of Microfluidic Fiber Chip Detection System

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稀有金属材料与工程 2006年第A03期35卷 525-526页

作者： bo Su da-fu Cui Chang-chun Liu Xing Chen State Key Lab. of Transducer Tech. Inst. of Electronics Chinese Academy of Sciences Beijing 100080 China

The diameter of the excitation beam was decreased greatly by integrating the fiber on the microfluidic chip as light propagation *** coupling efficiency of the fiber was improved with optical fiber collimation device coupling beam. The chip was placed in the darkroom to avoid the interference of the external *** cost of the instrument was decreased with a high brightness blue LED as excitation source;the performance of the system was valuated by the determination of FITC fluorescein with a minimum detectable concentration of 2.2×10^(-8) mol/L,the Signal-to-Noise Ratio (SNR) S/N=*** correlation coefficient of the detection system within the range of 1.8×10^(-7) mol/L～4×10^(-5)mol/L was 0.9972.

关键词： microfluidic chip light-emitting diode optical fiber detector

Magnetic Properties of Co 2D Antidot Arrays with Hexagonal Holes Using Colloidal Crystal Template Method

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Acta Metallurgica Sinica(English Letters) 2016年第5期29卷 409-413页

作者： Hong-Fei Qi da-bo Liu Song-Yan dai Tian-Min Wang Department of Steel and Rare-Noble Metals Beijing Institute of Aeronautical Materials Center of Condensed Matter and Material Physics Beihang University

In this work, Co 2D antidot arrays with well-ordered hexagonal holes ranging in size from 1.3 to 6.2 μm were fabricated by colloidal crystal template method. The geometry configuration and magnetic properties of the samples were investigated. An enormous increase in coercivity and squareness, as compared with the corresponding continuous film, was observed. Magnetic properties of Co 2D antidot arrays showed a close dependence on pore diameter. According to geometric calculation, the effect of the pore diameter on magnetic properties was also discussed. The Co 2D antidot arrays obtained by this method are promising candidates for high-density information storage.

关键词： Co antidot arrays Colloidal crystal template Hexagonal holes Magnetic properties

Calculation of Surface Excitation Parameters by a Monte Carlo Method

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Chinese Journal of Chemical Physics 2017年第1期30卷 83-89,I0002页

作者： Zhe Zheng bo da Shi-feng Mao Ze-jun Ding CAS Key Laboratory of Geospace Environment Department of Modern Physics University of Science and Technology of China Hefei 230026 China National Institute for Materials Science 1-2-1 Sengen Tsukuba Ibaraki 305-0047 Japan School of Nuclear Science and Technology University of Science and Technology of China Hefei 230026 China Hefei National Laboratory for Physical Sciences at the Microscale and Department of Physics University of Science and Technology of China Hefei 230026 China

Electron inelastic mean free path （IMFP） is an important parameter for surface chemical quantification by surface electron spectroscopy techniques. It can be obtained from analysis of elastic peak electron spectroscopy （EPES） spectra measured on samples and a Monte Carlo simulation method. To obtain IMFP parameters with high accuracy, the surface excitation effect on the measured EPES spectra has to be quantified as a surface excitation parameter （SEP）, which can be calculated via a dielectric response theory. However, such calculated SEP does not include influence of elastic scattering of electrons inside samples during their incidence and emission processes, which should not be neglected simply in determining IMFP by an EPES method. In this work a Monte Carlo simulation method is employed to determine surface excitation parameter by taking account of the elastic scattering effect. The simulated SEPs for different primary energies are found to be in good agreement with the experiments particularly for larger incident or emission angles above 60° where the elastic scattering effect plays a more important role than those in smaller incident or emission angles. Based on these new SEPs, the IMFP measurement by EPES technique can provide more accurate data.

关键词： Eelastic peak electron spectroscopy Surface excitation parameter Monte Carlo simulation

Effects of chromium on the corrosion and electrochemical behaviors of ultra high strength steels

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International Journal of Minerals,Metallurgy and Materials 2010年第3期17卷 282-289页

作者： Jin-yan Zhong Min Sun da-bo Liu Xiao-gang Li Tian-qi Liu School of Chemistry and Environmental Engineering China University of Mining and Technology （Beijing） Beijing 100083 China School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China Beijing Institute of Aeronautical Materials Beijing 100095 China

The effects of chromium on the corrosion and the electrochemical behaviors of ultra high strength steels were studied by the salt spray test and electrochemical methods. The results show that ultra high strength steels remain martensite structures and have anodic dissolution characteristic with an increase of chromium content. There is no typical passive region on the polarization curves of an ultra high strength stainless steel, AerMet 100 steel, and 300M steel. However, chromium improves the corrosion resistance of the stainless steel remarkably. It has the slowest corrosion rate in the salt spray test, one order of magnitude less than that of AerMet 100 and 300M steels. With the increase of chromium content, the polarization resistance becomes larger, the corrosion potential shifts towards the positive direction with a value of 545 mV, and the corrosion current density decreases in electrochemical measures in 3.5wt% NaCl solutions. Because of the higher content of chromium, the ultra high strength stainless steel has a better corrosion resistance than AerMet 100 and 300M steels.

关键词： ultra high strength steel corrosion rate chromium electrochemical behavior

Bulk Metallic Glasses: MRI Compatibility and Its Correlation with Magnetic Susceptibility

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Journal of Materials Science & Technology 2016年第6期32卷 496-504页

作者： da-bo Zhou Shao-Ping Wang Shao-Gang Wang Hong-Jun Ai Jian Xu School of Stomatology China Medical University Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences

Several bulk metallic glasses （BMGs） were selected to in vitro assess their magnetic resonance imaging （MRI） compatibility with agarose gel as a phantom, in terms of the extent of susceptibility artifacts in magnetic resonance image. The investigated metals include the ***2.3Cu26.9Si16.3, Zr61Ti2Cu2sA112, Cu50.4Nis.0Ti31Zr13 and Ti47Cu38Zr7.5Fe2.5Sn2Si1Ag2, together with pure titanium （CP-Ti） and Co-28Cr-6Mo alloy （ASTM-F799） for comparison. The artifact extent in MR images was quantitatively characterized according to the total volume in reconstructed 3D images with a series of slices under acquisition by fast spin echo （FSE） sequence and gradient echo （GRE） sequence. As indicated, artifact severity of the BMGs is much less than that of the CoCrMo alloy. The AuAgPdCuSi BMG manifested the smallest arti- fact among the four BMGs, while the TiCuZrFeSnSiAg BMG is comparative to the CP-Ti. The MRI compatibility of BMGs is ranked as a sequence of the Au-, Zr-, Cu- and Ti-based alloys. Dependence of material mag- netic susceptibility on artifact extent is also the case of the BMGs, even though it does not follow a simple linear relationship within a range of △χv = 30-180 ppm. These findings are of interest to reveal that the BMGs are potentially applied in the fields associated with an interventional MRI for MRI-guided surgeries.

关键词： Metallic glass MRI compatibility Magnetic susceptibility Metal-induced artifacts Biomaterials