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Improvement of elevated-temperature strength and recrystallization resistance via Mn-containing dispersoid strengthening in al-Mg-Si 6082 alloys

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Journal of Materials Science & Technology 2020年第4期39卷 135-143页

作者： chen Li Kun Liu x.-Grant chen Department of Applied Science University of Québec at ChicoutimiChicoutimiQC G7H 2B1Canada

The precipitation behavior of Mn-containing dispersoids in al-Mg-Si 6082 alloys with different Mn contents(0,0.5 and 1.0 wt%)during various heat treatments(300–500℃)was *** effects of dispersoids on elevated-temperature strength and recrystallization resistance during hot-rolling and post-rolling annealing were *** results showed that the dispersoids in the Mn-containing alloys(0.5 and 1.0%)began to precipitate at 350℃and reached the optimum conditions after 2–4 h at 400℃.However,the dispersoids coarsened with increasing holding time at temperatures above450℃.After the peak precipitation treatment at 400℃for 2 h,the yield strength at 300℃increased from 28 MPa(base alloy free of Mn)to 55 MPa(alloy with 0.5%Mn)and 70 MPa(alloy with 1%Mn),respectively,demonstrating a significant dispersoid strengthening effect at elevated *** addition,the dispersoids were thermally stable at 300℃for up to 1000 h holding owing to its relative high precipitation temperature(350–400℃),leading to the superior constant mechanical performance at elevated temperature during the long service *** hot rolling and post-rolling annealing,the presence of a large amount of dispersoids results in the higher Zener drag PZcompared with base alloy and then significantly improved the recrystallization *** alloy containing 0.5%Mn ex.ibited the highest recrystallization resistance among three ex.erimental alloys studied during the post-rolling process,likely resulted from the lower coarsening rate of dispersoids and the lower dispersoids free zone.

关键词： al-Mg-Si 6082 alloy Mn addition Dispersoid precipitation Elevated-temperature strength Recrystallization resistance

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Effects of Mn content on recrystallization resistance of AA6082 aluminum alloys during post-deformation annealing

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Journal of Materials Science & Technology 2020年第17期52卷 189-197页

作者： x.aoming Qian Nick Parson x.-Grant chen Department of Applied Science University of Quebec at ChicoutimiSaguenay G7H 2B1Canada Arvida Research and Development Centre Rio Tinto AluminumSaguenay G7S 4K8Canada

The microstructural evolutions under as-homogenized and as-deformed conditions and after the postdeformation annealing of AA6082 aluminum alloys with different Mn content(0.05 wt.%-1 wt.%)were studied by optical,scanning electron,and transmission electron *** results showed that the presence of a large amount ofα-al(Mn,Fe)Si dispersoids induced by Mn addition significantly improved the recrystallization *** the base alloy free of Mn,static recrystallization occurred after 2 h of annealing,and grain growth commenced after 4 h of annealing,whereas in Mn-containing alloys,the recovered grain structure was well-retained after even 8 h of *** alloy with 0.5%Mn ex.ibited the best recrystallization resistance,and a further increase of the Mn levels to 1%resulted in a gradual reduction of the recrystallization resistance,the reason for which was that recrystallization occurred only in the dispersoid-free zones(DFZs)and the increased DFZ fraction with Mn content led to an increase in the recrystallization *** variation in the dispersoid number density and a coarsening of dispersoids during annealing have a limited influence on the static recrystallization in Mn-containing alloys.

关键词： AA6082 alloys Mn effects Recrystallization resistance Dispersoid precipitation Post-deformation annealing

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Effects of diurnal adjustment on biases and trends derived from inter-sensor calibrated AMSU-A data

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Frontiers of Earth Science 2018年第1期12卷 1-16页

作者： H. chen x. ZOU Z. QIN Department of Atmospheric and Oceanic Sciences University of Colorado Boulder Colorado CO 80309 USA Earth System Science Interdisciplinary Center (ESSIC) University of Maryland College Park Maryland MD 20742 USA Joint Center for Data Assimilation Research and Applications Nanjing University of Information Science and Technology Nanjing 210044 China

Measurements of brightness temperatures from Advanced Microwave Sounding Unit-A （AMSU-A） temperature sounding instruments onboard NOAA Polar- orbiting Operational Environmental Satellites （POES） have been ex.ensively used for studying atmospheric temperature trends over the past several decades. Inter- sensor biases, orbital drifts and diurnal variations of atmospheric and surface temperatures must be considered before using a merged long-term time series of AMSU-A measurements from NOAA- 15, - 18, - 19 and MetOp-A. We study the impacts of the orbital drift and orbital differences of local equator crossing times （LECTs） on temperature trends derivable from AMSU-A using near-nadir observa- tions from NOAA-15, NOAA-18, NOAA-19, and MetOp-A during 1998 - 2014 over the Amazon rainforest. The double difference method is firstly applied to estimation of inter-sensor biases between any two satellites during their overlapping time period. The inter-calibrated observations are then used to generate a monthly mean diurnal cycle of brightness temperature for each AMSU-A channel. A diurnal correction is finally applied each channel to obtain AMSU-A data valid at the same local time. Impacts of the inter-sensor bias correction and diurnal correction on the AMSU-A derived long-term atmospheric temperature trends are separately quantified and compared with those derived from original data. It is shown that the orbital drift and differences of LECT among different POESs induce a large uncertainty in AMSU-A derived long-term warming/cooling trends. After applying an inter-sensor bias correction and a diurnal correction, the warming trends at different local times, which are approx.mately the same, are smaller by half than the trends derived without applying these corrections.

关键词： AMSU-A diurnal adjustment decadal tem-perature trend

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Engineering atomic Rb-N configurations to tune radical pathways for highly selective photocatalytic H2O2 synthesis coupled with biomass valorization

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Journal of Energy Chemistry 2025年第1期100卷 215-225页

作者： Jiaye Li Shuang Pan Yihuang chen Qiong Liu College of Chemistry and Materials Engineering Wenzhou University Guangdong Provincial Key Laboratory of Chemical Measurement and Emergency Test Technology (China) Institute of Analysis Guangdong Academy of Sciences (China National Analytical CenterGuangzhou)

Photocatalytic ox.gen reduction for hydrogen perox.de （H2O2） synthesis presents a green and costeffective production ***,achieving highly selective H2O2synthesis remains challenging,necessitating precise control over free radical reaction pathways and minimizing undesirable ox.dative ***,we report for the visible light-driven simultaneous co-photocatalytic reduction of O2to H2O2and ox.dation of biomass using the atomic rubidium-nitride modified carbon nitride（CNRb）.The optimized CNRb catalyst demonstrates a record photoreduction rate of 8.01 mM h-1for H2O2generation and photoox.dation rate of 3.75 mM h-1for furfuryl alcohol to furoic acid,achieving a remarkable solar-to-chemical conversion （SCC） efficiency of up to 2.27%.Ex.erimental characterizations and DFT calculation disclosed that the introducing atomic Rb–N configurations allows for the high-selective generation of superox.de radicals while suppressing hydrox.l free radical *** is because the Rb–N serves as the new alternative site to perceive a stronger connection position for O2adsorption and reinforce the capability to ex.ract protons,thereby triggering a high selective redox.product *** study holds great potential in precisely regulating reactive radical processes at the atomic level,thereby paving the way for efficient synthesis of H2O2coupled with biomass valorization.

关键词： Atomic economy Radical pathway regulation Rubidium atom coordination Biomass valorization

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Cyano migration-mediated radical-polar crossover cyclopropanation

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Science China Chemistry 2025年第01期 241-248页

作者： Ziqiang Wang Yasu chen Jie Li chen Zhu Key Laboratory of Organic Synthesis of Jiangsu Province College of Chemistry Chemical Engineering and Materials ScienceSoochow University Frontiers Science Center for Transformative Molecules Zhangjiang Institute for Advanced Study and Shanghai Key Laboratory for Molecular Engineering of Chiral Drugs Shanghai Jiao Tong University

We report a novel cyano migration-mediated radical-polar crossover process, whereby both the sulfonylcyanation of aliphatic alkenes and the formation of cyclopropanes are concurrently achieved. This transformation yields a diverse array of multisubstituted cyclopropanes under mild photocatalytic conditions. Mechanistic studies elucidate that the reaction proceeds via intramolecular nucleophilic substitution, leading to the formation of the cyclopropane derivatives.

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Electronic and magnetic structures of chain structured ironselenide compounds

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Frontiers of physics 2014年第4期9卷 465-471页

作者： Wei Li Chandan Setty x. H. chen Jiangping Hu State Key Laboratory of Functional Materials for Informatics and Shanghai Center for Superconductivity Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences Shanghai 200050 China Department of Physics and State Key Laboratory of Surface Physics Fudan University Shanghai 200433 China Department of Physics Purdue University West Lafayette IA 47907 USA Hefei National Laboratory for Physical Science at Microscale and Department of Physics University of Science and Technology of China Hefei 230026 China Beijing National Laboratory for Condensed Matter Physics and Institute of Physics Chinese Academy of Sciences Beijing 100190 China

Electronic and magnetic structures of iron selenide compounds Ce2O2FeSe2 （2212＊） and BaFe2Se3 （123＊） are studied by the first-principles calculations. We find that while all these compounds are composed of one-dimensional （1D） Fe chain （or ladder） structures, their electronic structures are not close to be quasi-lD. The magnetic ex.hange couplings between two nearest-neighbor （NN） chains in 2212＊ and between two NN two-leg-ladders in 123＊ are both antiferromagnetic （AFM）, which is consistent with the presence of significant third NN AFM coupling, a common feature shared in other iron-chalcogenides, FeTe （11＊） and KyFe2-x.e2 （122＊）. In magnetic ground states, each Fe chain of 2212＊ is ferromagnetic and each two-leg ladder of 123＊ form a block-AFM structure. We suggest that all magnetic structures in iron-selenide compounds can be unified into an ex.ended J1-J2-J3 model. Spin-wave ex.itations of the model are calculated and can be tested by future ex.eriments on these two systems.

关键词： first-principles calculations magnetism spin-wave ex.itations

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EFFECTS OF ZIRCONIUM ON MICROSTRUCTURES AND MECHANICal PROPERTIES OF MICROalLOYED STEELS

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Acta Metallurgica Sinica(English Letters) 2006年第5期19卷 319-327页

作者： T．H．x. x. chen P.H. Li Z.x. Yuan Technology Center of Wuhan Iron ＆ Steel （Group） Corp. Wuhan 430080 China School of Materials and Metallurgy Wuhan University of Science and TechnologyWuhan 430081 China

The effects of Zr on the microstructures and mechanical properties of microalloyed steels have been investigated by mechanical tests and microstructural observations. The microstructures in the Zr-doped steels are ferrite plus pearlite, which is similar to those in the Zr-free steel. With the increase in the Zr content, the lamellar structure reduces and even disappears. Sulfides and silicates that ex.st in the Zr-free steel are modified into fine ox.des in the Zr-bearing steel. When the Zr contents range from 0.01wt% to 0.03wt%, the low temperature toughness of the steel can be substantially improved while its room-temperature strength and ductility have no apparent change. The refinement of ferrite grain size by the addition of zirconium is one of the main reasons for this toughness improvement.

关键词： zirconium microalloyed steel microstructure mechanical property

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Half-quantized helical hinge currents in ax.on insulators

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National Science Review 2023年第9期10卷 154-162页

作者： Ming Gong Haiwen Liu Hua Jiang Chui-Zhen chen x.-C.x.e International Center for Quantum Materials School of Physics Peking University Center for Advanced Quantum Studies Department of Physics Beijing Normal University 3. School of Physical Science and Technology Soochow University 4. Institute for Advanced StudySoochow University 5. CAS Center for Excellence in Topological Quantum ComputationUniversity of Chinese Academy of Sciences

Fractional quantization can emerge in noncorrelated systems due to the parity anomaly,while its condensed matter realization is a challenging *** propose that in ax.on insulators(AIs),parity anomaly manifests a unique fractional boundary ex.itation:the half-quantized helical hinge *** helical hinge currents microscopically originate from the lateral Goos-H?nchen(GH) shift of massless side-surface Dirac electrons that are totally reflected from the ***,due to the presence of the massive top and bottom surfaces of the AI,the helical current induced by the GH shift is *** semiclassical wave packet analysis uncovers that the hinge current has a topological origin and its half quantization is robust to parameter ***,we propose an ex.erimentally feasible six.terminal device to identify the half-quantized hinge channels by measuring the nonreciprocal *** results advance the realization of the half-quantization and topological magneto electric responses in AIs.

关键词： ax.on insulator parity anomaly half-quantization Goos-Hänchen effect topological magnetoelectric effect

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Decolorization of Direct Black 22 by Aspergillus ficuum

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Journal of Environmental Sciences 2001年第4期13卷 472-475页

作者： Dong, x.-j. Du, Z.-y. chen, Z. Dept. of Biology/Environmental Sci. Wenzhou Normal College Wenzhou 325003 China

The decolorization of Direct Black 22 by Aspergillus ficuum has been studied. It was found that Aspergillus ficuum could effectively decolorize Direct Black 22 especially when grown as pelleted mycelia. Results showed that the media containing Direct Black 22 at 50 mg/L could be decolorized by 98.05% of the initial color in 24 h. The optimum pH and temperature of decolorization are 4.0 and 33 °C respectively. Aeration was quite beneficial to decolorization. Medium composition and the concentration of Direct Black 22 could affect the rate of decolorization. The dye degraded products assayed by UV-visible spectrophotometer and macroscopic observation showed that the decolorization of Direct Black 22 by mycelial pellets includes two important processes: bioadsorption and biodegradation. The degradation ex.eriment agree with the Michaelis-Menten kinetics equation.

关键词： Bioassay Biodegradation Color Concentration (process) Dyes pH Ultraviolet spectrophotometers

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Construction and Application of Multivariable Finite Element for Flat Shell Analysis

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Acta Mechanica Solida Sinica 2018年第4期31卷 391-404页

作者： x.ngwu Zhang Yanfei He Robert x. Gao Jia Geng x.efeng chen Jiawei x.ang State Key Laboratory for Manufacturing Systems Engineering Xi'an Jiaotong University Xi'an 710049 China School of Mechanical Engineering Xi ' an Jiaotong University Xi ' an 710049 China Department of Mechanical Engineering Case Western Reserve University Cleveland OH 44106 USA Zhejiang Provincial Key Laboratory of Laser Processing Robot/Key Laboratory of Laser Precision Processing & Detection Wenzhou University Wenzhou 325035 China

Based on B-spline wavelet on the interval （BSWI） and the multivariable generalized variational principle, the multivariable wavelet finite element for flat shell is constructed by combining the elastic plate element and the Mindlin plate element together. First, the elastic plate element formulation is derived from the generalized potential energy function. Due to its ex.ellent numerical approx.mation property, BSWI is used as the interpolation function to separate the solving field variables. Second, the multivariable wavelet Mindlin plate element is deduced and constructed according to the multivariable generalized variational principle and BSWI. Third, by following the displacement compatibility requirement and the coordinate transformation method, the multivariable wavelet finite element for fiat shell is constructed. The novel advantage of the constructed element is that the solving precision and efficiency can be improved because the generalized displacement field variables and stress field variables are interpolated and solved independently. Finally, several numerical ex.mples including bending and vibration analyses are given to verify the constructed element and method.

关键词： B-spline wavelet on the interval Elastic plate Mindlin plate Flat shell Multivariable

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