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journal of Materials Science & Technology 2020年第6期41卷 127-138页

作者： y.x.Lai W.Fan M.j.yin C.L.Wu j.H.Chen Center for High-Resolution Electron Microscopy College of Materials Science&EngineeringHunan UniversityChangsha 410082China Electron Microscopy Center Shenzhen UniversityShenzhen 518060China

In the slightly deformed Al-Mg-Si alloys,dislocation-induced precipitates are frequently observed,and they usually line up,forming sophisticated precipitation *** atomic-resolution electron microscopy in association with hardness measurements,we systematically investigated these precipitates in relation to the age-hardening responses of the *** study reveals that the majority of dislocation-induced complex precipitates are actually short-range ordered while long-range disordered polycrystalline precipitates and multiphase composite precipitates,including polycrystalline U2 precipitates,B’/U2,B’-2/U2,B’/B’-2/U2 and’/U2 composite *** is suggested that the formation of these complex precipitates is mainly owing to a high nucleation rate and rapid growth of different precipitate phases parallel to the associated dislocation *** dislocation-induced precipitates consume more Mg than Si from the matrix and have a high formation kinetics,they will have different impacts on the matrix precipitation in different types of Al-Mg-Si *** results further demonstrate that for the"normally-β"-hardened"alloy,their formation leads to a coarser precipitate microstructure in the matrix,whereas for the"normally-β’-hardened"alloy,their formation reverses the precipitation pathway in the matrix,resulting in a reduced age-hardening potential of the former alloy and an improved age-hardening potential of the latter alloy.

关键词： Al-Mg-Si alloys Precipitation Dislocation Age-hardening Electron microscopy

STUDy ON THE EFFECTS OF BREAKAGE OF SINGLE FIBER ON CREEP BEHAVIOR OF FIBER REINFORCED COMPOSITES

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Acta Metallurgica Sinica(English Letters) 2004年第4期17卷 498-502页

作者： x.j.Shao y.P.jiang Z.F.yue School of Mechanics Civil Engineering and Architecture Northwestern Polytechnical University Xi'an710072 ChinaSchool of Mechanics Civil Engineering and Architecture Northwestern Polytechnical University Xi'an710072 ChinaSchool of Mechanics Civil Engineering and Architecture Northwestern Polytechnical University Xi'an710072 China

A 3-D micro cell model with multi-fibers has been presented to study the effects of breakage of single fiber on the whole creep behavior of fiber reinforced composites by finite element method (FEM). Before the fiber breakage, the stresses of all fibers are identical. With the creep time increasing, stress in fiber increases but stress in matrix decreases. It is assumed that the fiber breakage occurs when the stress in fiber reaches a critical value. The stress redistribution resulted from the breakage of fiber has been obtained. The influence on the axial stress of the broken fiber is local. The stress in the all fiber sections is not uniform. There is a local stress concentration in the matrix. And this stress concentration in the matrix is more and more serious with the creep deformation. The stress transference of the loading due to the fiber breakage has been studies numerically. It is found that the fibers near to the broken fiber will take over more loading.

关键词： fiber reinforced composites breakage of fiber stress redistribution loading transference

First-Principles Study of Phase Stability and Mechanical Property of Co_3(Al,W) Precipitates with Different Ratio of Al to W in Co Base Alloys

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稀有金属材料与工程 2009年第A3期38卷 1-4页

作者： yao Q Su x M yan y Zhao L W Sun j Shanghai j.aotong University Shanghai 200240 China

The energetics, electronic structure and mechanical property of Co3(Al,W) precipitates with different ratio of Al to W in Co base alloys were investigated by the method of supercell and augmented plane waves plus local orbitals within generalized gradient approximation. The calculated results show that the L12 Co3(Al,W) precipitate is the most stable when the ratio of Al to W is equal to 1. When the content of W is higher than 18.5 at%, the L12 and hexagonal structures co-exist in Co3(Al,W) precipitates at 1173 K. It is also shown that the L12 ordered Co3(Al,W) precipitates have an obvious strengthening effect in the disordered fcc cobalt matrix.

关键词：铝电子结构力学性能碳酸

Experimental investigation of axial tensile and fatigue behaviors of HTS round strands

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Superconductivity 2023年第4期8卷 69-78页

作者： x.Q.Lai j.x.Zuo x.B.Hu T.Zhang j.D.Liu P.y.Li Southwestern Institute of Physics(SWIP) P.O.Box 432Chengdu 610041PR China Southwestern Institute of Physics ChengduSichuanPR China

For the development of high‐temperature superconducting(HTS)magnet systems of future fusion devices,a novel HTS round strand based on a stacking structure was designed and manufactured using second generation(2G)HTS *** mechanical loads during operation can result in irreversible degradation of the *** axial tension and fatigue loads need particular ***,it is important to investigate the electromechanical behavior of the round strand under various axial tension and cyclic *** this paper,the axial tensile and fatigue tests were conducted at 77 K,self‐*** 95%critical current(I_(c))retention as the criterion,the results of the tensile tests revealed that the average tensile stress and strain were as high as 344 MPa and 0.47%,*** characteristics were also investigated as a function of axial tensile *** significant performance degradation was observed up to 100,000 loading cycles with stress amplitudes ranging from 20 MPa to 200 *** degradation occurs after 16,000 loading cycles with 380 MPa as the maximum ***,the microscopic defects of the round strand samples due to fabrication imperfections and mechanical loading were investigated using metallographic microscope and scanning electron *** results presented in this paper are useful for comprehending and improving the mechanical behaviors of the strand in high‐field and large‐scale fusion magnet systems.

关键词： High‐temperature superconducting High‐field magnet Round strands Axial tensile and fatigue Microscopic defects

Non‐chromate conversion process for zinc coating with durable hydrophobicity and enhanced corrosion resistance

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Biosurface and Biotribology 2022年第3期8卷 266-277页

作者： j.y.Chen Z.y.Hu Z.x.Li x.L.Wang C.D.Gu j.P.Tu School of Materials Science and Engineering State Key Laboratory of Silicon MaterialsZhejiang UniversityHangzhouChina Key Laboratory of Advanced Materials and Applications for Batteries of Zhejiang Province HangzhouChina Zhejiang Ecological and Environmental Monitoring Center HangzhouChina Zhejiang Key Laboratory of Ecological and Environmental Monitoring Forewarning and Quality ControlHangzhouChina

A Zn‐based coating with durable hydrophobicity and good corrosion resistance was formed on a mild steel substrate,which involves electroplating Zn from a non‐aqueous electrolyte,followed by passivation in an oleic acid(OA)*** electrodeposited Zn coatings were porous,which facilitated the formation of a chemical conversion layer of Zn oleate(ZO)during OA *** Zn coating after passivation had a twolayer structure,which included an outer layer of ZO with a thickness of~26μm and an inner layer of Zn with a thickness of~6μ*** outer layer ZO is a type of metal soap with a smooth surface and durable hydrophobicity,such that water droplets can easily slip off its *** testing and electrochemical measurements in 3.5 wt.%NaCl aqueous solution indicate that the Zn coating after OA passivation exhibits outstanding anti‐corrosion properties compared with those exhibited by pure Zn *** corrosion products and mechanism of the two‐layer coating were *** study shows that smooth metal oleate coatings can provide hydrophobicity and corrosion resistance simultaneously to mild steel substrates.

关键词： Anti‐corrosion Electrodeposition Hydrophobic coating Passivation Zn oleate

A novel Mg-Gd-y-Zn-Cu-Ni alloy with excellent combination of strength and dissolution via peak-aging treatment

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journal of Magnesium and Alloys 2023年第2期11卷 720-734页

作者： y.H.Liu Z.R.Zhang j.Wang y.Li H.x.Li L.y.jia j.H.Wang j.S.Zhang State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083China Dekai Intelligent Casting Co. Ltd.Hebei 072750China

Inferior absolute strength and dissolution properties are the main bottlenecks for the widespread application of dissolvable magnesium alloys in complex working environments for unconventional oil and gas ***,a novel functional peak-aged Mg-9.5Gd-2.7y-0.9Zn-0.8Cu-0.4Ni(wt.%) alloy for fracturing tools is reported,and it possesses an ultimate tensile strength of 457.6 MPa,ultimate compressive strength of 620.7 MPa and dissolution rate of ~43.7 mg·cm^(-2)·h^(-1) in 3 wt.% KCl solutions at 93℃.The excellent strength of the agedalloy is primarily attributed to the combination of grain refinement,long-period stacking ordered(LPSO) strengthening,and precipitation strengthening induced by stacking fault and β’ phase,among which the precipitation strengthening is *** investigations confirm that the corrosion is triggered from the micro-galvanic coupling between the Mg matrix and the cathodic lamellar and block LPSO ***-shaped corrosion pits along with LPSO phases are subsequently formed,significantly accelerating *** β’ precipitates can effectively improve the strength without compromising the dissolution rate because of their nanoscale *** study provides an excellent material selection for dissolvable fracturing tools and presents a strategy by which a synergistic combination of strength and dissolution rate is achieved via peak-aging treatment.

关键词： Dissolvable magnesium alloy Peak-aging treatment Mechanical properties Micro-galvanic corrosion

A fast numerical method of introducing the strengthening effect of residual stress and strain to tensile behavior of metal matrix composites

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journal of Materials Science & Technology 2021年第28期87卷 167-175页

作者： j.F.Zhang x.x.Zhang H.Andrä Q.Z.Wang B.L.xiao Z.y.Ma Shi-changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China University of Chinese Academy of Sciences Beijing 100049China Fraunhofer Institute for Industrial Mathematics Fraunhofer-Platz 1Kaiserslautern 67663Germany

Thermal residual stress and strain(TRSS)in particle reinforced metal matrix composites(PRMMCs)are believed to cause strengthening effects,according to previous ***,the representative volume element(RVE)based computational homogenization technique was used to study the tensile deformation of PRMMCs with different particle aspect ratios(AR).The influence of TRSS was assessed quantitatively via comparing simulations with or without the cooling *** was found that the strengthening effect of TRSS was affected by the particle *** the average strengthening effect of TRSS,a fast method of introducing the strengthening effect of TRSS to the tensile behavior of PRMMCs was *** new method has reduced the computational cost by a factor *** effect of TRSS on continuous fiber-reinforced metal matrix composite was found to have a softening-effect during the entire tensile deformation process because of the pre-yield effect caused by the cooling process.

关键词： Metal matrix composites(MMC) Finite element analysis(FEA) Representative volume element(RVE) Residual stress and strain Aspect ratio

Phosphorus export by runoff from agricultural field plots with different crop cover in Lake Taihu watershed

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journal of Environmental Sciences 2001年第4期13卷 502-507页

作者： yan, W.-j. Huang, M.-x. Zhang, S. Tang, y.-j. Dept. of Envrn. Biogeochemistry Inst.Geographic Sci./Nat. Rsrc. Res. Chinese Academy of Sciences Beijing 100101 China

Runoff and soil losses from agricultural fields are investigated as major nonpoint sources of phosphorus (P) entering lakes of Eastern China. There is relatively little information on P transport from ricefield and cropland of Lake Taihu watershed in Eastern China. Soil and P in surface runoff from a series of plots in the watershed were evaluated under simulated rainfall conditions. The objectives of this study were to evaluate the effects of crop cover, slope, and fertilizer application on P concentrations in surface runoff and eroded soil. Accumulated sediment yields varied from 7.1 to 300 g/m2 for croplands, depending on management practices. For all experiment plots, weighted average concentrations of total-P (TP), dissolved P (DP) and particulate P (PP) are much higher than 0.02 mg/L, the limiting concentration for lake water. This result showed the potential contamination of lake water from agricultural surface runoff. Accumulated TP losses were 3.8 and 18.8 mg/m2 for ricefield and cropland, respectively. The estimated annual loss of TP was 0.74 kg/(hm2 · a) for cropland. Most of P loss is in the PP form, which accounts for more than 90% of TP loss for cropland.

关键词： Concentration (process) Crops Lakes Phosphorus Sediments Soils Watersheds

An insight into Mg alloying effects on Cu thin films:microstructural evolution and mechanical behavior

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journal of Materials Science & Technology 2020年第22期54卷 101-112页

作者： G.y.Li L.F.Cao j.y.Zhang x.G.Li y.Q.Wang K.Wu G.Liu j.Sun State Key Laboratory for Mechanical Behavior of Materials Xi'an Jiaotong UniversityXi'an710049China International joint Laboratory for Light Alloys(Ministry of Education) College of Materials Science and EngineeringChongqing UniversityChongqing400044China Electron Microscopy Center of Chongqing University Chongqing UniversityChongqing400044China

How to design ultra-strong,light-weight Cu alloys is a long-term pursuit in materials community,which is technically superior and cost-effective for their promising energy-saving *** this work,we prepared Cu-Mg alloyed thin films to study light element Mg alloying effects on the microstructure,hardness and strain rate sensitivity(SRS) of nanocrystalline Cu thin *** the studied Mg concentrationrange spanning from 0 at.% to 16.8 at.%,both the grain size and the twin spacing decrease monotonously with increasing Mg composition while Cu-2.8 at.% Mg sample has the highest twin fraction of ~75%.A combined strengthening model was employed to quantify the Mg concentration-dependent hardness of nanotwinned(NT) Cu-Mg thin films,in which the grain/twin boundary facilitates strengthening while the solute Mg atoms induce *** the constant rate of loading tests and the nanoindentation creep tests uncover that compared with pure Cu samples,the NT Cu-Mg thin films manifest much lower SRS,particularly in the creep tests,owing to the activation of dynamic strain aging effects.

关键词： Cu-Mg thin films Microstructure evolution Creep tests Hardness Strain rate sensitivity

Mechanical property and structural changes by thermal cycling in phase-separated metallic glasses

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journal of Materials Science & Technology 2021年第19期78卷 144-154页

作者： y.Tang H.B.xiao x.D.Wang Q.P.Cao D.x.Zhang j.Z.jiang International Center for New-Structured Materials(ICNSM) Laboratory of New-Structured MaterialsState Key Laboratory of Silicon Materialsand School of Materials Science and EngineeringZhejiang UniversityHangzhou310027China State Key Laboratory of Modem Optical Instrumentation Zhejiang UniversityHangzhou.310027China

Nondestructive cryogenically thermal cycling has been a simple but effective treatment to enhance mechanical properties of glassy ***,how the structural heterogeneities on nanometer scales are affected by thermal cycling is still an ***,we report the response of spatial heterogeneities in three selected Ti_(41)Zr_(25)Be_(28)Fe_(6),Zr_(56)Co_(14)Cu_(14)Al_(16)and Zr_(42)y_(14)Co_(22)Al_(22)(at.%)metallic glasses(MGs)with different compositions to the thermal cycling,which show significantly different structure and properties after the same treatments and could be ascribed to the joint contribution of relaxation and rejuvenation induced by thermal *** rejuvenation is initially prevailed in a Zr-y-containing MG,whereas the relaxation is dominant in a Cu-Co-containing MG,both eventually entering into a dynamic equilibrium *** employing nanometer-scale structural models,the intrinsic correlation between the spatial heterogeneity and thermal cycling is *** discovery could provide the fundamental understanding of the role of spatial heterogeneity in influencing the macroscopic properties of MGs via thermal cycling and help design high-performance glassy materials by tailoring their atomic structures with suitable thermal treatments.

关键词： Thermal cycling Metallic glass Spatial heterogeneity Relaxation Rejuvenation