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Twinnability Predication for fcc Metals

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Journal of Materials Science & Technology 2011年第2期27卷 97-100页

作者： B.Q.Li M.L.Sui S.x.mao Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Institute of Microstructure and Properties of Advanced Materials Beijing University of TechnologyBeijing 100124China Department of Mechanical Engineering and Materials Science University of PittsburghPittsburghPennsylvania 15261USA

Inherent twinnability of face-centered-cubic（fcc） metals was analyzed based on the direct competition between twinning partial dislocation nucleation and trailing partial dislocation nucleation,with which the twinnability of fcc metals can be simply expressed as function of the stacking-fault energy,the unstable stacking-fault energy,and the unstable twinningfault energy of fcc *** predicted twinnability ranking matched well with former experimental results and provided a physical insight to understand twinnability from crystallographic orientation and fault energy parameters.

关键词： Deformation twinning fcc metals Twinnability

In situ atomistic observation of the deformation mechanism of Au nanowires with twin–twin intersection

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Journal of Materials Science & Technology 2020年第18期52卷 118-125页

作者： Shuchun Zhao Qi Zhu xianghai An Hua Wei Kexing Song Scott x.mao Jiangwei Wang Center of Electron Microscopy and State Key Laboratory of Silicon Materials School of Materials Science&EngineeringZhejiang UniversityHangzhou 310027China School of Aerospace Mechanical&Mechatronic EngineeringThe University of SydneySydney 2006Australia Center for Hypergravity Experimental and Interdisciplinary Research.Zhejiang University Hangzhou 310027China School of Materials Science&Engineering Henan University of Science and TechnologyLuoyang 471023China Department of Mechanical Engineering and Materials Science University of PittsburghPittsburgh Pennsylvania15261USA

Twin–twin intersections are often observed in face-centered cubic(FCC)metallic nanostructures,which have important contributions to the plastic deformation and strengthening of FCC metals with low stacking fault ***,a deep insight into the underlying mechanism involved in the formation and evolution of twin–twin intersections remains largely lacking,especially in ***,by conducting the in situ straining experiments under high resolution transmission electron microscope(TEM),we directly visualize the dynamic evolution of a twin–twin intersection in Au nanowire at the *** shows that dislocations in the incoming twin can either glide onto or transmit across the barrier twin via dislocation interaction with the twin boundary,resulting in the twin–twin *** twinning and de-twinning of the twin–twin intersection govern the whole deformation of the *** findings reveal the dynamic behaviors of twin–twin intersection under mechanical loading,which benefits further exploration of FCC metals and engineering alloys with twin–twin intersection structures.

关键词： In situ TEM Twin-twin intersection Au nanowire Twinning/de-twinning Dislocation-twin interaction

Early Paleozoic granulite-facies metamorphism and anatexis in the northern West Qinling orogen： Monazite and zircon U-Pb geochronological constraints

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Science China Earth Sciences 2017年第5期60卷 943-957页

作者： mao xiaoHong ZHANG Jianxin YU ShengYao LI YunShuai YU xingxing LU ZengLong Institute of Geology Chinese Academy of Geological SciencesBeijing 100037China School of Earth and Space Sciences Peking UniversityBeijing 100871China Submarine Geosciences and Prospecting Techniques MOE and College of Marine GeosciencesOcean University of ChinaQingdao 266100China Laboratory for Marine Geology Qingdao National Laboratory for Marine Science and TechnologyQingdao 266235China Institute of Surface-Earth System Science Tianjin UniversityTianjin 300072China

In the northern West Qinling orogen(WQO), granulite-facies metamorphic rocks are recognized within the Qinling Complex. These rocks are composed of amphibole-bearing two-pyroxene granulite and garnet-sillimanite gneiss with widespread migmatitization. We investigate three granulite-facies samples and one leucosome sample from the Qinling Complex, which are suitable for U-Pb analyses of zircon and monazite. SHRIMP and LA-ICPMS U-Pb age dating of zircon and monazite from two pelitic granulites provides weighted mean ages of 430±4 Ma(MSWD=0.88) and 433±4 Ma(MSWD=0.27), *** on the petrographic characteristics and zircon CL imagery, we postulated a ca. 430 Ma metamorphic timing for the pelitic granulites. LA-ICPMS zircon U-Pb data from an amphibole two-pyroxene granulite sample reports two weighted mean age groups:424±3 Ma(MSWD=0.45) and 402±3 Ma(MSWD=1.4), which were interpreted as granulite-facies metamorphic and retrograde ages, respectively. LA-ICPMS U-Pb dating of zircons from the leucosome sample yields a weighted mean age of 426±2 Ma(MSWD=0.3), which is interpreted as the crystallization age of the leucosome. These data indicate that the West QOB experienced early Paleozoic granulite-facies metamorphism and anatexis similar to the East QOB. However, it remains unclear whether the early Paleozoic granulite facies metamorphism resulted from an arc setting created by the northward subduction of the Shangdan ocean or from a continental collisional orogenic event.

关键词： West Qinling Granulite Migmatite U-Pb age dating Metamorphism Early Paleozoic

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Discrete twinning dynamics and size-dependent dislocation-to twin transition in body-centred cubic tungsten

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Journal of Materials Science & Technology 2022年第11期106卷 33-40页

作者： Jiangwei Wang Anik H.M.Faisal xiyao Li Youran Hong Qi Zhu Hongbin Bei Ze Zhang Scott x mao Christopher R.Weinberger Center of Electron Microscopy and State Key Laboratory of Silicon Materials School of Materials Science and EngineeringZhejiang UniversityHangzhou 310027China Department of Mechanical Engineering Colorado State UniversityCO 80523USA School of Materials Science and Engineering Zhejiang UniversityHangzhou 310027China Department of Mechanical Engineering and Materials Science University of PittsburghPittsburghPA 15261USA Wenzhou Key Laboratory of Novel Optoelectronic and Nano Materials Institute of WenzhouZhejiang UniversityWenzhou 325006China

Body-centred cubic(BCC) metals are known to have unstable intrinsic stacking faults and high resistance to deformation twinning, which can strongly influence their twinning behaviour. Though twinning mechanisms of BCC metals have been investigated for more than 60 years, the atomistic level dynamics of twinning remains under debate, especially regarding its impact on competition between twinning and slip. Here, we investigate the atomistic level dynamics of twinning in BCC tungsten(W) nanowires using in situ nanomechanical testing. Quantitative experimental studies directly visualize that deformation twins in W nanowires have a minimum size of six-layers and grow in increments of approximately three-layers at a time, in contrast to the layer-by-layer growth of deformation twins in face-centred cubic metals. These unique twinning dynamics induces a strong competition with ordinary dislocation slip,as exhibited by a size-dependent dislocation-to-twin transition in W nanowires, with a transition size of ~40 nm. Our work provides physical insight into the dynamics of twinning at the atomic level, as well as a size-dependent dislocation-twinning competition, which have important implications for the plastic deformation in a broad class of BCC metals and alloys.

关键词： Body-centred cubic Deformation twin Twinning dynamics Dislocation-to-twin transition In situ nanomechanical testing

Spacial Distribution Characteristics, Activity and Degradation Capability of the Biofilm in Integrated Vertical-flow Constructed Wetland

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Journal of Environmental Science and Engineering 2010年第10期4卷 57-62页

作者： J. Li x.x. mao Z.B. Wu Life Science School Hubei Normal Unibersity Huangshi 435002 China Fisheries College of Jimei University Xiamen 361002 China State Key Laboratory of Freshwater Ecology and Biotechnology Institute of Hydrobiology Chinese Academy of Sciences Wuhan430072 China

The spacial distribution characteristics, activity and degradation capability of the biofilm in integrated vertical-flow constructed wetland were investigated. Results showed that the biofilm widely distributed in the substrate of integrated vertical-flow constructed wetland and mainly in the 0-10 cm top layer where the activity ofdehydrogenase of the biofilm was also higher than that of other layers. The water quality could also affect the activity of the biofilm, for the TF（1,3,5-Triphenylformazan） amount reduced by the biofim incubated in water of the higher eutrophication was larger, too. The PCP （pentachlorophenol） removal rate by the substrate with biofilm was 1.5 times that without biofilm. In total, the biofilm of the down-flow chamber appeared larger biomass, higher dehydrogenase activity and stronger degradation capability of organic contamination than that in up-flow chamber and it was the major place for removal of the organic matters in waste water.

关键词： Integrated vertical-flow constructed wetland biofilm distribution activity of dehydrogenase degradation capacity

Direct observation of Pt nanocrystal coalescence induced by electron-excitation-enhanced van der Waals interactions

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Nano Research 2014年第3期7卷 308-314页

作者： Ying Jiang Yong Wang Yu Yang Zhang Zhengfei Zhang Wentao Yuan Chenghua Sun xiao Wei Casey N. Brodsky Chia-Kuang Tsung Jixue Li xiaofeng Zhang Scott x. mao Shengbai Zhang Ze Zhang Center of Electron Microscopy and State Key Laboratory of Silicon Materials Department of Materials Science and Engineering Zhejiang University Hangzhou 310027 China Department of Physics Applied Physics and Astronomy Rensselaer Polytechnic Institute Troy New York 12180 USA Centre for Computational Molecular Science Australian Institute for Bioengineering and Nanotechnology University of Queensland St Lucia QLD 4072 Australia Department of Chemistry Boston College Chestnut Hill MA 02467 USA Hitachi High Technologies America Pleasanton CA 94588 USA Department of Mechanical Engineering and Materials Science University of Pittsburgh Pittsburgh PA 15261 USA

Nanocrystal coalescence has attracted paramount attention in nanostructure fabrication in the past decades. Tremendous endeavor and progress have been made in understanding its mechanisms, benefiting from the development of transmission electron microscopy. However, many mechanisms still remain unclear, especially for nanocrystals that lack a permanent dipole moment standing on a solid substrate. Here, we report an in situ coalescence of Pt nanocrystals on an amorphous carbon substrate induced by electron-excitation- enhanced van der Waals interactions studied by transmission electron microscopy and first principles calculations. It is found that the electron-beam-induced excitation can significantly enhance the van der Waals interaction between Pt nanocrystals and reduce the binding energy between Pt nanocrystals and the carbon substrate, both of which promote the coalescence. This work extends our understanding of the nanocrystal coalescence observed in a transmission electron microscope and sheds light on a potential pathway toward practical electron- beam-controlled nanofabrication.

关键词： Pt nanocrystals coalescence electron excitation van der Waals interactions

Overview and Prospect of Distributed Energy P2P Trading

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Energy Engineering 2025年第1期122卷 379-404页

作者： Jiajia Liu Mingxing Tian xusheng mao School of Automation and Electrical Engineering Lanzhou Jiaotong UniversityLanzhou730070China

After a century of relative stability in the electricity sector,the widespread adoption of distributed energy resources,along with recent advancements in computing and communication technologies,has fundamentally altered how energy is consumed,traded,and *** change signifies a crucial shift as the power system evolves from its traditional hierarchical organization to a more decentralized *** the heart of this transformation are innovative energy distribution models,like peer-to-peer(P2P)sharing,which enable communities to collaboratively manage their energy *** effectiveness of P2P sharing not only improves the economic prospects for prosumers,who generate and consume energy,but also enhances energy resilience and *** allows communities to better leverage local resources while fostering a sense of collective responsibility and collaboration in energy ***,there is still no extensive implementation of such sharing models in today’s *** on distributed energy P2P trading is still in the exploratory stage,and it is particularly important to comprehensively understand and analyze the existing distributed energy P2P trading *** paper contributes with an overview of the P2P markets that starts with the network framework,market structure,technical approach for trading mechanism,and blockchain technology,moving to the outlook in this field.

关键词： Distributed energy P2P market mechanisms classification and comparison

MECHANICAL PROPERTIES OF A TYPE OF Al-ALLOY WELD

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Acta Metallurgica Sinica(English Letters) 1997年第3期10卷 192-197页

作者： ZH Tu Z Zhang L.Z. Zhaoand T.x. mao (Cryogenic Laboratory, Chinese Academy of Sciences, Beijing 100080, China) (Institute of Mechanics, Chinese Academy of Sciences, Beijing 100080, China )

The mechanical properties of a type of Al-alloy weld including strength, fracture tough-ness and ductility were comprehensively studied at different temperatures. The frac-ture behavior and weld micro features were also characterized. The surface crack test method was adopted to study the fracture toughness and a multiple specimen test ap-paratus was designed to perform the cryogenic experiments. The relationship between the mechanical properties and temperature was obtained together with the fracture toughness distribution in the weld.

关键词： Al-alloy weld mechanical properties surface crack low temperature

Study of the Transport Behavior of Multispherical Proppant in Intersecting Fracture Based on Discrete Element Method

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Energy Engineering 2025年第1期122卷 185-201页

作者： Chengyong Peng JianshuWu mao Jiang Biao Yin Yishan Lou CNOOC Research Institute Company Limited Beijing100028China School of Petroleum Engineering Yangtze UniversityWuhan430100China Hubei Key Laboratory of Oil and Gas Drilling and Production Engineering(Yangtze University) Wuhan430100China

To analyze the differences in the transport and distribution of different types of proppants and to address issues such as the short effective support of proppant and poor placement in hydraulically intersecting fractures,this study considered the combined impact of geological-engineering factors on *** reservoir production parameters and the discrete elementmethod,multispherical proppants were ***,a 3D fracture model,based on the specified conditions of the L block,employed coupled(Computational Fluid Dynamics)CFD-DEM(Discrete ElementMethod)for joint simulations to quantitatively analyze the transport and placement patterns of multispherical proppants in intersecting *** indicate that turbulent kinetic energy is an intrinsic factor affecting proppant ***,the efficiency of placement and migration distance of low-sphericity quartz sand constructed by the DEM in the main fracture are significantly reduced compared to spherical ceramic proppants,with a 27.7%decrease in the volume fraction of the fracture surface,subsequently affecting the placement concentration and damaging fracture *** to small-angle fractures,controlling artificial and natural fractures to expand at angles of 45°to 60°increases the effective support length by approximately 20.6%.During hydraulic fracturing of gas wells,ensuring the fracture support area and post-closure conductivity can be achieved by controlling the sphericity of proppants and adjusting the perforation direction to control the direction of artificial fractures.

关键词： Hydraulic fracturing discrete element method proppant sphericity CFD-DEM