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Effect of Ti,Sc and Zr additions on microstructure and mechanical properties of rheo-diecasting Al-6Zn-2Mg-2Cu alloys

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China Foundry 2023年第2期20卷 125-133页

作者： Sai-heng Hou Jian Feng Song Chen Fan Zhang da-quan li State Key Laboratory of Nonferrous Metals and Processes GRINM Group Co.Ltd.Beijing 100088China GRIMAT Engineering Institute Co. Ltd.Beijing 101407China General Research Institute for Nonferrous Metals Beijing 100088China

The microstructure and mechanical properties of rheo-diecasting Al-6Zn-2Mg-2Cu alloys microalloyed with Ti,Sc and Sc+Zr were studied by optical microscopy(OM),scanning electron microscopy(SEM),X-ray diffraction(XRD),hardness testing,and tensile *** swirled equilibrium enthalpy device(SEED)process was introduced to prepare the semisolid *** show that the addition of Ti,Sc,and Sc+Zr refines the grain size and improves the uniformity of the semisolid slurry and then suppresses the growth of theα-Al grain during solution heat *** microstructure of the four alloys in as-cast state mainly consists of sphericalα-Al and the Mg(Al,Cu,Zn)_(2)(η)eutectic ***,primary Al_(3)Sc,Al_(3)(Sc,Zr)and Al_(3)Zr are also found in the micro-alloying *** solution and aging heat treatment,most of the Mg(Al,Cu,Zn)_(2) phases dissolve into theα-Al matrix,while part of Mg(Al,Cu,Zn)_(2) phases transform to Al_(2)CuMg(S)***,the coarse primary Al_(3)Sc and Al_(3)(Sc,Zr)still remain in the matrix,and promote crack initiation and *** the tensile strength of 553 MPa,yield strength of 463 MPa and elongation of 13.4%at T6 state,trace Ti addition generates more attractive mechanical properties than the other three alloys.

关键词： Al-Zn-Mg-Cu alloys rheo-diecasting microstructure mechanical properties micro-alloying

Microstructure and mechanical property of MIM 418 superalloy

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Rare Metals 2018年第1期37卷 35-39页

作者： Fu-Bao Yang Yan-Hong Jing dan li lin Zhang da-quan li Qiang Zhu National Engineering and Technology Research Center for Nonferrous Metal Matrix Composites General Research Institute for Nonferrous Metals Powder Metallurgy Research Institute University of Science and Technology Beijing

In this study, the influence of hot isostatic pressing（HIP） process on the 418 alloy produced by metal injection molding（MIM） technique（named as MIM 418）was investigated based on the characteristic analysis of 418 alloy powder. And comparison analysis of the microstructure and mechanical property between the MIM 418 and as-cast 418 alloys was performed by scanning electron microscopy（SEM）, energy-dispersive spectroscopy（EDS）,and X-ray diffraction（XRD）. The results show that MIM418 alloy exhibits fine grain（~30 μm） and uniform microstructure. The defects existing in MIM 418 alloy formed during sintering process can be eliminated through HIP treatment, and the relative density increases from97.0 % to 99.5 %. The mechanical property can be improved significantly because of the elimination of defects, and the tensile strength and elongation are1,271 MPa and 16.8 %, respectively, which are increased by 34.5 % and 180 % compared with K418 alloy after solution heat treatment.

关键词： K418 superalloy Metal injection molding Hot isostatic pressing Microstructure Mechanical property

Forming conditions of blisters during solution heat treatment of Al–Si alloy semi-solid die castings

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Rare Metals 2023年第11期42卷 3851-3858页

作者： Hong-Xing Lu Qiang Zhu Stephen P.Midson Wen-Ying Qu Fan Zhang da-quan li National Engineering and Technology Research Center for Nonferrous Metal Matrix Composites General Research Institute for Nonferrous MetalsBeijing100088China Department of Mechanical and Energy Engineering Southern University of Science and TechnologyShenzhen518055China

In the present study,numerical simulation method was used to analyze the conditions,resulting in the formation of blisters during solution heat *** formation is considered to occur as the height of blister reaches 5μ*** effects of process parameters on the magnitude of the forming temperatures of blister(Tb)were *** kinds of Al-Si alloys were used to analyze the effect of mechanical properties of the alloys on blister forming *** results show that decreasing the initial pressure in gas hole,the long-short axial ratio of gas hole and the size of gas hole,as well as increasing the depth of gas hole and the strength of alloy are helpful to increase the critical temperature of forming *** conclusions are helpful for casters to understand the conditions controlling blister formation during solution heat treatment and take actions to avoid the blister defects.

关键词： Blister Forming condition Semi-solid die casting Aluminum alloy

Effects of Cu content on microstructure and mechanical properties of rheo-diecasting Al-6Zn-2Mg-xCu alloys

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China Foundry 2022年第4期19卷 321-326页

作者： Zhi-guang Ding Sai-heng Hou Song Chen Ze-hua liu da-quan li Jian Feng Fan Zhang li-ming Peng National Engineering Research Center of light Alloy Net Forming and Key State Laboratory of Metal Matrix Composites School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China General Research Institute for Nonferrous Metals Beijing 101407China

A systematic study on how Cu content affects the microstructure and mechanical properties of rheo-diecasting Al-6Zn-2Mg-xCu alloys during solution treatment and ageing heat treatment was *** swirled enthalpy equilibrium device(SEED)was adopted to prepare the semi-solid slurry of Al-6Zn-2Mg-xCu *** microstructure development and mechanical properties were studied using optical microscopy(OM),scanning electron microscopy(SEM),X-ray diffraction(XRD),differential scanning calorimetry(DSC),as well as hardness and tensile *** grain boundary and shape factor were calculated using image processing software(Image-Pro Plus 6.0).Results show that the alloys are composed of typical globular primaryα-Al grains,eutectic phases,and smaller secondaryα-Al *** solution and ageing heat treatment,the eutectic phases are dissolved into Al matrix when the Cu content is lower than 1.5wt.%,while some eutectic phases transform into Al_(2)CuMg(S)phases and remain at grain boundaries when Cu content reaches 2wt.%.T6 heat treatment significantly enhances the mechanical properties of rheo-diecasting Al-6Zn-2Mg-xCu *** Cu concentration is 0.5wt.%-1.5wt.%,the ultimate tensile strength,yield strength and elongation of T6 treated alloys rise to around 500 MPa,420 MPa,and 18%,respectively.

关键词： Al-Zn-Mg-Cu alloy rheo-diecasting Cu content mechanical properties heat treatment

Electro-reductive carboxylation of acyclic C(sp^(3))–C(sp^(3))bonds in aromatic hydrocarbons with CO_(2)

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Science China Chemistry 2024年第10期67卷 3366-3372页

作者： Chuan-Kun Ran quan Qu Yang-Yi Tao Yi-Fei Chen li-li liao Jian-Heng Ye da-Gang Yu Key Laboratory of Green Chemistry&Technology of Ministry of Education College of ChemistrySichuan UniversityChengdu 610064China West China School of Public Health and West China Fourth Hospital Sichuan UniversityChengdu 610064China

Despite the recent advances in the selective functionalization of C–C bonds in specific substrates,cleavage and functionalization of C–C bonds in acyclic substrates,such as ethane derivatives,remains *** contrast to the well-developed functionalization of one carbon fragment after C–C bond cleavage,herein,we report a novel electro-reductive carboxylation of C(sp^(3))–C(sp^(3))bond in multi-aryl ethanes with carbon dioxide(CO_(2))by utilizing both carbon ***,this reaction exhibits an atom-,step-economic approach for the synthesis of carboxylic acids,fulfilling principal aspirations of organic ***,this method features mild reaction conditions,broad substrate scope,and good functional group *** and asymmetric substrates bearing primary,secondary,or tertiary C(sp^(3))–C(sp^(3))bonds are all amenable to this strategy,enabling one or two structurally different carboxylic acids to be facilely constructed at the same *** investigations indicate that carbanions might be the key intermediates in this reaction,which could be captured by CO_(2)efficiently.

关键词： carbon dioxide electrochemistry C(sp^(3))–C(sp^(3))bonds cleavage reductive carboxylation

Interference-induced suppression of particle emission from a Bose-Einstein condensate in lattice with time-periodic modulations

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Chinese Physics B 2024年第10期33卷 153-158页

作者： Long-quan Lai Zhao li School of Science Nanjing University of Posts and TelecommunicationsNanjing 210023China School of Electronic Engineering Chengdu Technological UniversityChengdu 611730China

Emission of matter-wave jets from a parametrically driven condensate has attracted significant experimental and theoretical attention due to the appealing visual effects and potential metrological *** this work,we investigate the collective particle emission from a Bose-Einstein condensate confined in a one-dimensional lattice with periodically modulated interparticle *** give the regimes for discrete modes,and find that the emission can be distinctly *** configuration induces a broad band,but few particles are ejected due to the interference of the matter *** further qualitatively model the emission process and demonstrate the short-time *** engineering provides a way to manipulate the propagation of particles and the corresponding dynamics of condensates in lattices,and may find application in the dynamical excitation control of other nonequilibrium problems with time-periodic driving.

关键词： Bose-Einstein condensate matter-wave jet periodic modulation

Measurement of acceleration and angular velocity of particles during a 3D silo discharge

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Particuology 2024年第9期92卷 61-71页

作者： Tongtong Mu Yiming li quan Chen Ran li Hui Yang College of Medical Instrument Shanghai University of Medicine and Health SciencesShanghai201318China School of Optical-Electrical and Computer Engineering University of Shanghai for Science and TechnologyShanghai200093China

Accurate measurement of the three-dimensional(3D)movement of discrete particles is crucial for comprehending complex granular rheology in *** this paper,the acceleration and angular velocity of particles in 3D silos are measured by using a spherical detector based on inertial technology and magnetic positioning *** acceleration of particles is the largest in the center of silos,which suggest that the resistance generated by friction and extrusion is the ***,the angular velocity distribution follows lognormal function except for particles near the *** correlation between acceleration and angular velocity is opposite in different flow *** reveals for the first time that the extent to which the resultant force on the particles affects their rotational motion is related to the flow *** results have practical significance for regulating the granular flow pattern and optimizing the structural design of silos.

关键词： Granularflow Silo Angular velocity Acceleration

KnowledgeMapping of Hybrid Solar PV andWind Energy Standalone Systems: A Bibliometric Analysis

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Energy Engineering 2024年第7期121卷 1781-1803页

作者： quan Zhou Haiyang li School of Mechanical and Electrical Engineering Central South University of Forestry and TechnologyChangsha410004China

Renewable energy is becoming more attractive as traditional fossil fuels are rapidly depleted and expensive,and their use would release *** systems that use both wind and solar energy are more reliable and efficient than those that utilize only one *** renewable energy systems(HRES)are viable for remote areas operating in standalone *** paper aims to present the state-of-the-art research on off-grid solar-wind hybrid energy systems over the last two *** than 1500 published articles extracted from the Web of Science are analyzed by bibliometric methods and processed by CiteSpace to present the results with figures and *** countries and highly cited authors are identified,and hot topics with hotspot articles are shown in landscape and timeline *** trends and new developments related to techno-economic analysis and microgrids,as well as the application of HOMER software,are predicted based on the analysis of citation ***,the opportunities of hybrid energy systems for sustainable development are discussed,and challenges and possible solutions are *** study of this paper provides researchers with a comprehensive understanding and intuitive representation of standalone solar-wind hybrid energy systems.

关键词： Wind energy solar PV standalone citation bursts emerging trends

Constitutive model of viscoelastic dynamic damage for the material of gas obturator in modular-charge howitzer

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Defence Technology（防务技术） 2024年第9期39卷 203-216页

作者： Zhonggang li Longmiao Chen Yifan li Yufeng Jia quan Zhang School of Mechanical Engineering Nanjing University of Science and TechnologyNanjing 210094China Technology Center Shanxi North Machine-building Co.Ltd.Taiyuan 030009China Research and Development Department Kelong New Material Technology Co.Ltd.Xianyang 712000China

In order to investigate the mechanical response behavior of the gas obturator of the breech mechanism,made of polychloroprene rubber(PCR), uniaxial compression experiments were carried out by using a universal testing machine and a split Hopkinson pressure bar(SHPB), obtaining stress-strain responses at different temperatures and strain rates. The results revealed that, in comparison to other polymers, the gas obturator material exhibited inconspicuous strain softening and hardening effects;meanwhile, the mechanical response was more affected by the strain rate than by temperature. Subsequently, a succinct viscoelastic damage constitutive model was developed based on the ZWT model, including ten undetermined parameters, formulated with incorporating three parallel components to capture the viscoelastic response at high strain rate and further enhanced by integrating a three-parameter Weibull function to describe the damage. Compared to the ZWT model, the modified model could effectively describe the mechanical response behavior of the gas obturator material at high strain rates. This research laid a theoretical foundation for further investigation into the influence of chamber sealing issues on artillery firing.

关键词： Breech mechanism Gas obturator Polychloroprene rubber Constitutive model Strain rate damage