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Revealing the grain size dependent hot workability and deformation mechanisms in a Mg-Zn-Y alloy

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Journal of Magnesium and Alloys 2023年第4期11卷 1461-1471页

作者： Ruiqing Lu Zhiming xu Fulin Jiang shiwei xu Dingfa Fu Hui Zhang Jie Teng College of Materials Science and Engineering Hunan UniversityChangsha 410082China State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan UniversityChangsha 410082China

Despite the industrial significance of grain size for enhancing mechanical properties and formability,the in-depth deformation mechanisms at elevated temperature are still *** investigate the functions of grain size on hot workability and deformation mechanisms,three groups of Mg-1.2Zn-0.2Y alloy specimens with different grain sizes were hot compressed and then studied by combining constitutive model,processing map and microstructural *** results showed that the enhanced hot workability accompanying low deformation activation energy and small instability regime was obtained with refined grain *** hot deformation,the decreased grain size in Mg1.2Zn-0.2Y alloy mainly improved the plastic deformation homogeneity,especially for the weakened local straining around grain *** a result,the dynamic recrystallization nucleation and texture development at lower strain level were influenced by the initial grain *** higher strain magnitude,the growth and coarsening of dynamic recrystallized grains would further release strain localization and improve hot workability,while the texture was less ***,unlike the primary basal slip and deformation twinning in the specimen with coarse grain at low temperature,non-basal slips of dislocations were initiated with less deformation twins in the specimens with refined grain size.

关键词： Mg-Zn-Y alloy Hot workability Plastic deformation Grain size Texture

Effects of alkalinity on interaction between EPS and hydroxy-aluminum with different speciation in wastewater sludge conditioning with aluminum based inorganic polymer flocculant

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Journal of Environmental Sciences 2021年第2期33卷 257-268页

作者： Weijun Zhang Mingyue Tang Dandan Li Peng Yang shiwei xu Dongsheng Wang School of Environmental Studies China University of GeosciencesWuhan 430074China Hubei Provincial Engineering Research Center of Systematic Water Pollution Control Wuhan 430074China School of Civil and Architecture Engineer Northeast Electric Power UniuersityJilin 132012China CECEP Engineering Technology Research Institution Beijing 100082China

Extracellular polymeric substances(EPS)form a stable gel-like structure to combine with water molecules through steric hindrance,making the mechanical dewatering of wastewater sludge considerably ***/flocculation has been widely applied in improving the sludge dewatering performance,while sludge properties(organic fraction and solution chemistry conditions)are highly changeable and have important effects on sludge flocculation *** this work,the alkalinity effects on sludge conditioning with hydroxy-aluminum were comprehensively investigated,and the interaction mechanisms between EPS and hydroxy-aluminum with different speciation were *** results showed that the effectiveness of hydroxy-aluminum conditioning gradually deteriorated with increase in ***,the polymeric hydroxy-aluminum(Al 13)and highly polymerized hydroxy-aluminum(Al 30)were hydrolysed and converted into amorphous aluminum hydroxide(Al(OH)3),which changed the flocculation mechanism from charge neutralization and complexing adsorption to hydrogen bond ***,both Al 13 and Al 30 showed higher binding capacity for proteins and polysaccharides in EPS than monomeric aluminum and Al(OH)*** 13 and Al 30 coagulation changed the secondary structure of proteins in EPS,which caused a gelation reaction to increase molecular hydrophobicity of proteins and consequently sludge *** study provided a guidance for optimizing the hydroxy-aluminum flocculation conditioning of sludge with high solution alkalinity.

关键词： Coagulation/flocculation Hydroxy-aluminum Hydrolysis reaction Extracellular polymeric substances

Analytical bi-level multi-local-world complex network model on fresh agricultural products supply chain

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International Journal of Agricultural and Biological Engineering 2022年第1期15卷 208-215页

作者： Yunqing Liu shiwei xu Jiajia Liu Jiayu Zhuang Agricultural Information Institute of Chinese Academy of Agricultural Sciences Beijing 100081China Key Laboratory of Agricultural Information Service Technology Ministry of Agriculture and Rural AffairsBeijing 100081China Institute of Environment and Sustainable Development in Agriculture Chinese Academy of Agriculture ScienceBeijing 100081China Research Center of Agricultural Monitoring and Early Warning Engineering Technology Beijing 100081China

Lately,in some regions and seasons in China,urban consumers have paid high in buying fresh agricultural products while farmers get unreasonable income from producing *** seek the reason for the phenomenon and explore ways to simulate it,this study constructed and implemented a complex network model named the Bi-Level Multi-Local-World(BI-MLW model)with characteristics of an interdependent coupling relationship between its *** verify the validity of the model,this study implemented an experimental simulation under Small Decentralized Operation Mode(SDOM)and Large Centralized Operation Mode(LCOM)scenarios using Cucurbita pepo and Cucumber in the Tianjin area of China as sample empirical *** indicate that nodes do not increase edges rapidly which reflects that even large firms in agricultural business cannot occupy markets ***,under the SDOM scenario the BI-MLW model exposes scale-free features with a small average degree value and low average clustering coefficient,while under the LCOM scenario,the model displays a rising average clustering coefficient and a lowered average path *** of which are consistent with the common view in literature and features of ***,the BI-MLW model specially designed for fresh agricultural products supply chain can improve the descriptive ability than conventional Erdös-Rényi(ER),Barabási-Albert(BA),Bianconi-Barabási(BB)network models.

关键词： fresh agricultural products supplying process supply chain complex network multi-local-world model

Microstructure characteristics and mechanical properties of Al/Mg joints manufactured by magnetic pulse welding

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Journal of Magnesium and Alloys 2023年第7期11卷 2366-2375页

作者： Congcong Zhu shiwei xu Wenli Gao Yifan Meng Sen Lin Lu Dai College of Materials Science and Engineering Hunan UniversityChangsha 410082China State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan UniversityChangsha 410082China Beijing Spacecrafts Beijing 100094China

The effective connection of 1050 Al and AZ31 Mg was realized by magnetic pulse *** maximum tensile-shear force of the dissimilar Al/Mg metal lap joint reached 97%of that of the 1050 Al alloy base material by optimizing the process *** microstructure of dissimilar Al/Mg welded joints was analysed by Scanning Electron Microscope(SEM),Energy Dispersive Spectrometer(EDS)and Electron Backscattered Diffraction(EBSD).The results show that the key to obtaining high shear strength of Al/Mg dissimilar metal joints is mainly due to the following two *** the one hand,grain refinement and element interdiffusion occur at the *** the other hand,no intermetallic compounds are formed at the interface.

关键词： Al/Mg dissimilarmaterials Magneticpulsewelding Mechanicalproperties Interface EBSD

Recent progress and perspectives in additive manufacturing of magnesium alloys

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Journal of Magnesium and Alloys 2022年第6期10卷 1511-1541页

作者： Zhuoran Zeng Mojtaba Salehi Alexander Kopp shiwei xu Marco Esmaily Nick Birbilis College of Engineering and Computer Science Australian National UniversityACT.2601 Australia Additive Manufacturing Group Singapore Institute of Manufacturing Technology(SIMTech)Agency forScienceTechnology and Research(A∗STAR)73 Nanyang Drive637662 Singapore Meotec GmbH Philipsstr.8AachenGermany State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan UniversityChangsh1410082 China Department of Materials Science and Engineering Massachusetts Institute of TechnologyCambridgeMA 02139United States of America Volvo Materials Technology Laboratory Volvo GroupLundbyGothenburg 41715Sweden

Magnesium alloys remain critical in the context of light-weighting and advanced devices. The increased utilisation of magnesium(Mg)each year reveals growing demand for its Mg-based alloys. Additive manufacturing(AM) provides the possibility to directly manufacture components in net-shape, providing new possibilities and applications for the use of Mg-alloys, and new prospects in the utilisation of novel physical structures made possible from ‘3D printing’. The review herein seeks to holistically explore the additive manufacturing of Mg-alloys to date, including a synopsis of processes used and properties measured(with a comparison to conventionally prepared Mg-alloys). The challenges and possibilities of AM Mg-alloys are critically elaborated for the field of mechanical metallurgy.

关键词： Magnesium Additive manufacturing Microstructure 3D printing Mechanical properties Electrochemical properties

Optimisation of alloy composition for highly-formable magnesium sheet

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International Journal of Minerals,Metallurgy and Materials 2022年第7期29卷 1388-1395页

作者： Zhuoran Zeng Mingzhe Bian shiwei xu Weineng Tang Chris Davies Nick Birbilis Jianfeng Nie College of Engineering and Computer Science Australian National UniversityACT.2601Australia Department of Materials Science and Engineering Monash UniversityVIC 3800Australia State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan UniversityChangsha 410082China Research Institute(R&D Center) Baosteel Group CorporationShanghai 201999China Department of Mechanical and Aerospace Engineering Monash UniversityVIC 3800Australia

The effectiveness of Ca or Gd addition on ductility and formability of Mg-Zn-Zr based dilute alloys in deep drawing has not been systematically compared *** this study,formable Mg-Zn-Gd-Zr and Mg-Zn-Ca-Zr sheet alloys are produced by hot *** sheets have similarly weakened basal texture,but the sheet of the Mg-Zn-Gd-Zr alloys has higher ductility and formability than that of Mg-Zn-Ca-Zr *** combined addition of 0.2wt%Ca and 0.4wt%Gd to the Mg-1Zn-0.5Zr(wt%)alloy leads to a Mg-1Zn-0.4Gd-0.2Ca-0.5Zr alloy that has even better ductility,and its formability during deep drawing is comparable to the benchmark Al6016 *** increase in Ca content from 0.2wt%to 0.5wt%leads to decreased sheet ductility and formability,predominantly due to grain boundary embrittlement.

关键词： magnesium sheet alloy texture microstructure formability solute segregation

Unravelling the precipitation evolutions of AZ80 magnesium alloy during non-isothermal and isothermal processes

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Journal of Materials Science & Technology 2021年第16期75卷 184-195页

作者： Longqing Tang Guowei Bo Fulin Jiang shiwei xu Jie Teng Dingfa Fu Hui Zhang College of Materials Science and Engineering Hunan UniversityChangsha 410082China State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan UniversityChangsha 410082China

The precipitation evolutions of Mg-Al-Zn alloys play essential roles in their mechanical properties,corrosion performance,formability,plastic deformation mechanisms and texture *** the present work,the precipitation evolutions of AZ80 magnesium alloy during both non-isothermal and isothermal processes were unraveled by utilizing in situ electrical resistivity monitoring,hardness testing,differential scanning calorimetry and microstructural *** results showed that discontinuous precipitation(DP)and continuous precipitation(CP)occurred competitively during non-isothermal and isothermal *** precipitation of dominantβ-Mg17 Al12 phase during non-isothermal processes was highly dependent on the thermal *** isothermal processes,the precipitation behavior of AZ80 magnesium alloy could be considered as the functions of holding temperature and *** lower temperatures,massive DP and CP were gradually formed to equally strengthen the *** higher temperatures,the Ostwald coarsening was characterized in the later stages and indicated to slightly soften the *** time-temperature-precipitation curves and quantitative precipitate evolution were estimated to unravel precipitation characteristics and their strengthening functions.

关键词： Magnesium alloy Precipitation Thermal processes In situ electrical resistivity Strengthening

Dynamic microstructure evolution and mechanical properties of dilute Mg-Al-Ca-Mn alloy during hot rolling

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Journal of Materials Science & Technology 2022年第34期129卷 1-14页

作者： shiwei xu Congcong Zhu Zhanhong Lin Chen Jin S.Kamado K.Oh-ishi Yun Qin College of Materials Science and Engineering Hunan UniversityChangsha 410082China State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan UniversityChangsha 410082China Qinghai Salt Lake Teli Magnesium Co.Ltd. Xining 810000China Department of Mechanical Engineering Nagaoka University of TechnologyNagaoka 940-2188Japan Toyota Central R&D Labs. Inc.41-1 YokomichiNagakuteAichi 480-1192Japan Research Institute(R&D Centre) Baowu Steel Group CorporationShanghai 201900China

The dynamic microstructure and texture of dilute Mg-0.50Al-0.71Ca-0.33Mn(wt.%) during hot rolling at two slab temperatures were investigated by electron backscattered diffraction(EBSD) and high resolution transmission electron microscopy(HRTEM). The results show that the development of the rolling microstructures is to first form {10–12} extension twins in the original grains, thereby forming the extension-twinned regions, and then to further form {10–11}-{10–12} double twins and kinks in the extension-twinned regions, and finally to form continuous dynamic recrystallized(continuous DRXed)grains in the double twins and the cross parts of the shear-deformed coarse extension-twinned *** extension twins, double twins and kinks show a decisive effect on the formation of rolling *** number of {10–11}-{10–12} double twins and resultant the continuous DRX process are strongly affected by the rolling slab temperature and the reduction thickness per pass. By optimizing the rolling conditions, texture and microstructures of the multi-pass rolled Mg-Al-Ca-Mn alloy sheets are successfully modified. Although the total alloy content is only 1.5 wt.%, these Mg-Al-Ca-Mn alloy sheets show much higher strength than the commercial Mg-3Al-1 Zn(wt.%)(AZ31B) sheet.

关键词： Mg-Al-Ca-Mn alloy Hot rolling Dynamic recrystallization Texture control Mechanical properties

Development of portable user-interactive holographic information collector for agricultural product markets

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International Journal of Agricultural and Biological Engineering 2020年第3期13卷 143-153页

作者： shiwei xu Denghua Li Yongen Zhang Wei Chen Jiayu Zhuang Jiajia Liu Shengwei Wang Agricultural Information Institute of Chinese Academy of Agricultural Sciences Beijing 100081China Key Laboratory of Agricultural Information Service Technology Ministry of Agriculture and Rural AffairsBeijing 100081China Research Center of Agricultural Monitoring and Early Warning Engineering Technology Beijing 100081China

The efficient and accurate collection of agricultural product market information serves as the basis for the effective regulation of agricultural product *** achieve a comprehensive,accurate,and timely collection of agricultural product market information,this study puts forth a technique for collecting holographic information of agricultural product markets.A portable human-machine interaction device with an Advanced RISC(reduced instruction set computer)Machines(ARM)-based processor as the core is *** information such as agricultural product market trading time,trading place,product name,price,and trading volume can be *** embedded technology and component technology,innovative agricultural product market positioning,and matching,standardized collection,and data processing,and in combination with intelligent algorithms for analysis and early warning,a mobile application terminal for information collection is developed,namely,a holographic information collector for agricultural product markets(named Nongxincai).By using a layered structure,the hardware integrates microprocessor,storage,power,application and communication interface,and human-machine interaction *** device has the advantages of miniaturization,the whole-machine power consumption of less than 0.5 W,and continuous operating time of at least 10 h.A supporting software system for Nongxincai has also been developed,in which Microsoft Windows Mobile 6.5 is employed as the operating system,and the CPU frequency is up to 600 *** configuration fully meets the computing requirements of map processing and large-volume data processing and has high *** has been popularized and applied in 12 provinces/municipalities in *** has played an important role in the monitoring and early warning of different varieties of agricultural products and target prices of soybean and cotton.

关键词： agricultural product market holographic information portable user-interactive information collector monitoring and early warning