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Chemical short-range orders in high-/medium-entropy alloys

Journal of Materials Science & Technology 2023年第16期147卷 189-196页

作者： xiaolei wu State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of ScienceBeijing 100190China University of Chinese Academy of Science Beijing 100049China

High(or medium)-entropy alloys(H/MEAs)are complex concentrated solid solutions prone to develop the chemical short-range orders(CSROs),as an indispensable structural constituent to make H/MEAs essentially different from the traditional *** CSROs are predicted to play roles in dislocation behaviors and mechanical *** far,the image of CSROs is built up by the theoretical modeling and computational simulations in terms of the conventional concept,i.e.,the preference/avoidance of elemental species to satisfy the short-ranged ordering in the first and the next couple of nearest-neighbor atomic *** these simulated CSROs,however,the structural image is missing on the atomic scale,even though the lattice periodicity does not exist in the ***,it is pending as to the issues if and what kind of CSRO may be formed in a specific H/*** these are ascribed to the challenge of experimentally seeing the *** recently,the breakthrough does not appear to convincingly identify the CSROs in the H/MEAs by using the state-of-the-art transmission electron *** be specific,the electron diffractions provide solid evidence to doubtlessly ascertain *** structure motif of CSROs is then constructed,showing both the lattice structure and species ordering occupation,along with the stereoscopic topography of the *** is suggested that the CSROs,as the first landscape along the path of development of the local chemical ordering,offer one more route to substantially develop the ordered structure on the atomic scale in the H/MEAs,parallel to the existing grain-leveled *** findings of CSROs make a step forward to understand the CSROs-oriented relationship between the microstructure and mechanical *** review focuses on the recent progress mainly in the experimental aspects of the identification,structure motif,and mechanical stability in CSROs,along with the chemical medium-range orders as the growing CSROs。

关键词： Chemical short-range order Electron diffraction Transmission electron microscopy Structure motif Chemical medium-range order High-/medium-entropy alloys

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Deformation induced hcp nano-lamella and its size effect on the strengthening in a CoCrNi medium-entropy alloy

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Journal of Materials Science & Technology 2021年第23期82卷 122-134页

作者： Yan Ma Muxin Yang Fuping Yuan xiaolei wu State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of SciencesNo.15West RoadNorth 4th RingBeijing100190China School of Engineering Science University of Chinese Academy of SciencesNo.19(A)Yuquan RoadShijingshan DistrictBeijing100049China

Deformation-induced hcp nano-lamellae with various widths and interspacings were observed in the Co Cr Ni medium-entropy alloy(MEA)under high strain rate and cryogenic temperature in the present *** hardness was found in the cryogenic-deformed samples compared to the room temperature-deformed samples without hcp ***,size effects of embedded hcp nano-lamellae on the tensile behaviors in the fcc Co Cr Ni MEA were investigated by molecular dynamics *** overall strengthening was found to have two components:phase strengthening and extra interface strengthening,and the interface strengthening was observed to be always stronger than the phase *** overall strengthening and interface strengthening were found to increase with increasing width and decreasing interspacing of embedded hcp *** samples with small spaced hcp nano-lamellae are even stronger than the pure hard hcp phase due to the extra interface *** samples with larger width of embedded hcp nano-lamellae can provide stronger resistance for dislocation slip and *** were observed to be formed in the embedded hcp *** density of phase boundaries and newly formed twin boundaries can provide more barriers for dislocation glide in the other slip systems,resulting in higher strength for samples with smaller interspacing.

关键词： Strengthening mechanisms Phase transformation Twinning Medium entropy alloys Molecular dynamics simulations

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Micro-scale mechanics of the surface-nanocrystalline Al-alloy material

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Science China(Physics,Mechanics & Astronomy) 2004年第1期47卷 86-100页

作者： WEI Yueguang ZHU Chen wu xiaolei LNM Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China LNM Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China LNM Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China

Based on the microscopic observations and measurements, the mechanical behavior of the surface-nanocrystallized Al-alloy material at microscale is investigated experimentally and theoretically. In the experimental research, the compressive stress-strain curves and the hardness depth curves are measured. In the theoretical simulation, based on the material microstructure characteristics and the experimental features of the compression and indentation, the microstructure cell models are developed and the strain gradient plasticity theory is adopted. The material compressive stress-strain curves and the hardness depth curves are predicted and simulated. Through comparison of the experimental results with the simulation results, the material and model parameters are determined.

关键词： surface-nanocrystallized material, Al-alloy, microstructure cell model, size effect.

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Succession of bacterial community along with the removal of heavy crude oil pollutants by multiple biostimulation treatments in the Yellow River Delta,China

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Journal of Environmental Sciences 2011年第9期23卷 1533-1543页

作者： Sulin Yu Shuguang Li Yueqin Tang xiaolei wu Department of Energy and Resources Engineering College of Engineering Peking University Beijing 100871 China

Multiple biostimulation treatments were applied to enhance the removal of heavy crude oil pollutants in the saline soil of Yellow River *** of the soil bacterial community were monitored using the terminal restriction fragment length polymorphism （T-RFLP） and clone library *** 140-day microcosm experiments showed that low C：N：P ratio,high availability of surfactant and addition of bulking agent significantly enhanced the performance,leading to the highest total petroleum hydrocarbon ***,the bacterial community was remarkably changed by the multiple biostimulation treatments,with the Deltaproteobacteria,Firmicutes,Actinobacteria,Acidobacteria and Planctomycetes being inhibited and the Alphaand Beta-proteobacteria and some unknown Gammaproteobacteria bacteria being *** addition,different hydrocarbon-degraders came to power in the following *** the first stage,the Alcanivorax-related Gammaproteobacteria bacteria dominated in the biostimulated soil and contributed mainly to the biodegradation of easily degradable portion of the heavy crude *** the bacteria belonging to Alphaproteobacteria,followed by bacteria belonging to Candidate division OD1,became the dominant oil-degraders to degrade the remaining recalcitrant constituents of the heavy crude oil.

关键词： heavy crude oil contamination biostimulation bacterial community T-RFLP Yellow River Delta saline soil

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An energy-equilibrium model for complex stress effect on fatigue crack initiation

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Science China(Physics,Mechanics & Astronomy) 2014年第5期57卷 916-926页

作者： ZHAO SiCong XIE JiJia ZHAO AiGuo wu xiaolei State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of Sciences

Based on Tanaka and Mura’s fatigue model and Griffith theory for fracture,an energy-equilibrium model was proposed to explain the complex stress effect on fatigue *** the summation of the elastic strain energy release and the stored strain energy of accumulated dislocations reach the surface energy of a crack,the fatigue crack will initiate in *** to this model,for multiaxial stress condition,the orientation of the crack initiation and the initiation life can be deduced from the energy equilibrium *** the uniaxial fatigue loading with mean stress,the relation between the maximum stress or the minimum stress and the stress amplitude is in agreement with an ellipse equation on the constant life *** the ratio of the mean stress to stress amplitude is less than a critical value-0.17,and the stress amplitude keeps constant,the fatigue crack initiation life will decrease with the increase of the compress mean *** this model,the mean stress does not cause damage accumulation with the fatigue cycles in crack *** this reason,the loading sequence of different load levels would induce the cumulative damage to deviate from the Palmgren-Miner cumulative damage *** procedure of estimating the damage under random loading is also discussed.

关键词： fatigue initiation mean stress effect multiaxial fatigue Tanaka-Mura model damage accumulation

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Temporal-spatial Characteristics of the Urbanization of Rural Land in Xinjiang

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Chinese Journal of Population,Resources and Environment 2006年第3期4卷 37-44页

作者： Lei Jun wu Shixin Zhang xiaolei Xinjiang Institute of Ecology and Geography Chinese Academy of Sciences Urumqi 830011 China

Relying on remote sensor technology, GIS and Land--sat TM digital images,the authors use spatial and statistical analysis to examine the temporal-spatial characteristics of the change caused by urban construction in Xinjiang’s rural areas from the end of the 1980s to the end of the 1990s. The primary findings show the following: 1) The urban construction in rural areas has increased drastically. The expansion speed of urban land use has accelerated over the past decade. The sub-land use changes caused by the urbanization of rural are characterized by salient regional differentiation among the three main regions and among the 85 counties of Xinjiang. 2) The shift of land use is mostly characterized by cultivated land and grassland being used for urban and industrial projects. Moreover, this change of land use is characteristic of regional differences. 3) Factors of rural-urban construction land use changes in Xinjiang, are undoubtedly affected by natural environment, social, economic conditions, and to a larger degree by population growth, GDP development and industrial development..

关键词： land use change rural-urban construction land use temporal-spatial characteristics

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Superior dynamic shear properties by structures with dual gradients in medium entropy alloys

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Journal of Materials Science & Technology 2023年第22期153卷 166-180页

作者： Shuang Qin Muxin Yang Ping Jiang Jian Wang xiaolei wu Hao Zhou Fuping Yuan State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of Science15 Beisihuan West RoadBeijing 100190China School of Engineering Science University of Chinese Academy of Sciences19A Yuquan roadBeijing 100049China Nano and Heterogeneous Materials Center School of Materials Science and EngineeringNanjing University of Science and TechnologyNanjing 210094China

Structures with single gradient and dual gradients have been designed and fabricated in an Al_(0.5)Cr_(0.9)FeNi_(2.5)V_(0.2) medium entropy *** with dual gradients(with increasing grain size and a decreasing volume fraction of nanoprecipitates from the surface to the center)were observed to show much better dynamic shear properties compared to both structures with single grainsize gradient and coarse-grained structures with homogeneously distributed ***,the dual gradients have a synergetic strengthening/toughening effect as compared to the sole effect of a single gradient and the sole precipitation *** of the adiabatic shear band(ASB)is delayed and propagation of ASB is slowed down in structures with dual gradients compared to structures with single gradients,resulting in better dynamic shear properties.A higher magnitude of strain gradient and higher density of geometrically necessary dislocations are induced in the structures with dual gradients,resulting in extra strain *** density dislocations,stacking faults,and Lomer-Cottrell locks can be accumulated by the interactions between these defects and B2/L1_(2) precipitates,due to the higher volume fraction of nanoprecipitates in the surface layer of the structures with dual gradients,which could retard the early strain localization in the surface layer for better dynamic shear properties.

关键词： Medium-entropy alloys Gradient structures Precipitates Strain hardening Dynamic properties Adiabatic shear band

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Tobacco two-component gene NTHK2

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Chinese Science Bulletin 2001年第7期46卷 574-577页

作者： ZHANG Jinsong XIE Can wu xiaolei DU Baoxing CHEN Shouyi Plant Biotechnology Lab Institute of GeneticsChinese Academy of SciencesBeijing 100101China Tianjin Institute of Horticulture Engineering Tianjin 300192China

By using a previously isolated tobacco two-component gene NTHK1 as a probe, we screened a cDNA library and obtained a homologous gene designated NTHK2. Sequencing analysis revealed that NTHK2 encoded a putative ethylene receptor homolog and contained a histidine kinase domain and a receiver domain. In the histidine kinase domain, the histidine at the phosphorylation site was replaced by an asparagine. Southern analysis indicated that NTHK2 was present at low copies in tobacco genome. The expression of NTHK2 was studied using a competitive RT-PCR method. It was found that, in young flower buds, NTHK2 was expressed abundantly, while in other organs or tissues, it was expressed in a low level. When leaf was subjected to wounding (cutting) treatment, NTHK2 expression was increased. When tobacco seedlings were stressed with PEG and heat shock, NTHK2 transcription was also enhanced. Other treatments showed little effects. These results indicated that NTHK2 might be involved in the developmental processes and

关键词： tobacco two-component gene stress.

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Effects of water and nitrogen rate on grain-filling characteristics under high-low seedbed cultivation in winter wheat

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Journal of Integrative Agriculture 2024年第12期23卷 4018-4031页

作者： Junming Liu Zhuanyun Si Shuang Li Lifeng wu Yingying Zhang xiaolei wu Hui Cao Yang Gao Aiwang Duan Institute of Farmland Irrigation Chinese Academy of Agricultural Sciences/Key Laboratory of Crop Water Use and RegulationMinistry of Agriculture and Rural AffairsXinxiang 453002China Graduate School of Chinese Academy of Agricultural Sciences Beijing 100081China Shandong Academy of Agricultural Machinery Sciences Jinan 250000China Binzhou Academy of Agricultural Sciences Binzhou 256600China

A high-efficiency mode of high-low seedbed cultivation(HLSC)has been listed as the main agricultural technology to increase land utilization ratio and grain yield in Shandong Province,***,limited information is available on the optimized water and nitrogen management for yield formation,especially the grain-filling process,under HLSC mode.A three-year field experiment with four nitrogen rates and three irrigation rates of HLSC was conducted to reveal the response of grain-filling parameters,grain weight percentage of spike weight(GPS),spike moisture content(SMC),and winter wheat yield to water and nitrogen *** four nitrogen rates were N1(360 kg ha^(-1) pure N),N2(300 kg ha^(-1) pure N),N3(240 kg ha^(-1) pure N),and N4(180 kg ha^(-1) pure N),respectively,and the three irrigation quotas were W1(120 mm),W2(90 mm),and W3(60 mm),*** showed that the determinate growth function generally performed well in simulating the temporal dynamics of grain weight(0.989

关键词： high-low seedbed cultivation water and nitrogen grain filling determinate growth equation wheat yield

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Hardening after annealing in nanostructured 316L stainless steel

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Nano Materials Science 2020年第1期2卷 80-82页

作者： Zhongchen Zhou Shuaizhuo Wang Jiansheng Li Yusheng Li xiaolei wu Yuntian Zhu Nano and Heterogeneous Materials Center School of Materials Science and EngineeringNanjing University of Science and TechnologyNanjing210094China State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of SciencesBeijing100190China Department of Materials Science and Engineering North Carolina State UniversityRaleighNC27695USA

In this work,coarse-grained 316 L stainless steels were cold rolled with a thickness reduction of^83%(CR 83%).After annealing,the behaviors of the nanostructured stainless steel samples were systematically investigated in the temperatures range of 200C–*** was found that with increasing annealing temperature the volume fraction of theα0-martensite first increased to reach a maximum value at 400C,then the volume fraction decreased with further increases of the annealing *** yield strength was increased from 1400 MPa to 1720 MPa after annealing;this strong hardening effect in cold rolled 316 L stainless steel was mainly attributed to the increase of the volume fraction ofα0-martensite.

关键词： Metals and alloys Nanostructure Heterostructure 316L stainless steel Annealing hardening Martensitic transformation

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