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Experimental Investigation on the LCF Behavior Affected by Manufacturing Defects and Creep Damage of One Selective Laser Melting Nickel-Based Superalloy at 815℃

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Acta Metallurgica Sinica(English Letters) 2020年第4期33卷 514-527页

作者： Xiao-An Hu Gao-Le Zhao Yun Jiang Xian-Feng Ma Fen-cheng liu Jia Huang cheng-li dong School of Aircraft Engineering Nanchang Hangkong UniversityNanchang 330063China Jiangxi Key Laboratory of Micro Aeroengine Technology Nanchang 330063China Sino-French Institute of Nuclear Engineering and Technology Sun Yat-Sen UniversityZhuhai 519082China National Defence Key Discipline Laboratory of light Alloy Processing Science and Technology Nanchang 330063China School of Aeronautics and Astronautics Central South UniversityChangsha 410083China Materials Evaluation Center for Aeronautical and Aeroengine Application AECC Beijing Institute of Aeronautical MaterialsBeijing 100095China

Uniaxial tensile tests and stress-controlled low-cycle fatigue(LCF) and creep-fatigue interaction(CFI) tests of Inconel 625 alloy manufactured by selective laser melting(SLM) were performed at 815℃ in air *** microstructure was characterized by optical microscopy and scanning electron microscopy after *** results confirmed that significant embrittlement and large scatter in LCF life are resulted from manufacturing *** CFI life is decreased sharply to approximately dozens of cycles with the accumulated creep strain;however,the selected dwell time(i.e.,60 s and 300 s)exhibits low sensitivity to the fracture time and elongation to *** embrittlement of SLM Inconel 625 was proposed to be due to the low grain uniformity and precipitation of carbides at the grain *** to the quality of the SLM process,the accelerated initiation and propagation of fatigue crack are caused by the present unmelted powder particles,which result in the large dispersion of LCF ***,due to the accumulation of creep damage,cracks in the CFI test are initiated along the grain boundaries and then linked together,contributing to a significant decline in fatigue life.

关键词： Selective laser melting Low-cycle fatigue Creep-fatigue interaction Failure analysis

Viscosity Measurements of Fe-Si-B-Cu-Nb-C Metallic Glass Melts by an Oscillating Crucible Method

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Chinese Physics Letters 2003年第3期20卷 395-397页

作者： li cheng-dong Tian Xue-Lei Chen Xi-Chen A.G. Ilinsky Key Laboratory of liquid Structure and Heredity of Materials Ministry of Education Shandong University Ji'nan 250061 Institute of Metal Physics National Academy of Sciences Ukraine Ukr 36 Vernadsky Blvd. UA-03680 Kiev Ukraine

Dependence of the dynamic viscosity of new type of Fe-based amorphous alloy (Fe68.5Si13.5B9Cu1Nb3C5) melt on temperature is investigated by using a torsional oscillation viscometer. The temperature dependence of the viscosity can be fitted by the Arrhenius relation and Fulcher expression as ln η = 0.082 + 1463.48/T and ln η = 6.75×10-5 + 954.71/(T-608.36), where η is the viscosity in units of cP and T is the temperature in units of K. The results show that the Arrhenius relation is more suitable in high temperature region, while the Fulcher expression is more appropriate in undercooled region. Combining the Differential scanning calorimetry data and free-volume model, the glass forming ability of Fe68.5Si13.5B9Cu1Nb3C5 alloy is discussed.

关键词： Viscosity

Synthesis and characterization of new soluble poly(aryl ether nitrile)s containing phthalazinone moiety

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Chinese Chemical Letters 2007年第5期18卷 595-597页

作者： Ming Jing Wang cheng liu li Ming dong Xi Gao Jian Department of Polymer Science ＆ Materials Dalian University of Technology Dalian 116012 China

A series of novel poly（aryl ether nitrile）s containing phthalazinone moiety were synthesized by the nucleophilic displacement reaction of bisphenol-like monomers （I） with 2,6-difluorobenzonitrile. The inherent viscosities ranged from 0.46 to 1.07 dL g^-1. The glass transition temperatures were in the range of 277-295℃, and the temperatures for 10% weight loss in nitrogen atmosphere were found between 495 and 527 ℃. The structures of these resultant polymers were confirmed by FT-IR and 1^H NMR. Moreover, the properties of poly（aryl ether nitrile）s including solubility and crystallinity were also studied.

关键词： Poly(aryl ether nitrile)s Phthalazinone Heat-resistance Solubility

An Al-12Si/ZnS powder inoculant for eutectic silicon in Al-12Si alloy

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China Foundry 2022年第2期19卷 149-157页

作者： Ying Wang Pan-yu Chen Yu-hui lin Mei Zhao cheng-dong li College of Materials Science and Engineering Qingdao University of Science&TechnologyQingdao 266042China

To obtain high-performance Al-Si-based cast alloys,refinement and modification of Si phases are *** Al-12Si/ZnS powder inoculant was designed and fabricated using a chemical bath deposition *** efficiency of the inoculant for modifying the eutectic Si phase in as-cast Al-12Si alloy was *** show that Al-12Si/ZnS powder can significantly refine the eutectic Si in Al-Si cast *** best refinement effect for eutectic Si is achieved with 17.5wt.%Al-12Si/ZnS *** long needle-shaped eutectic Si with a length of 18μm was modified into approximately spherical shape with a diameter of 6.53μm,which is evenly distributed throughout the *** E2EM model calculation indicates that the inter-plane misfit(F_(p))and inter-atomic spacing misfit(F_(r))between ZnS and Si are all less than 0.5%,which confirms that ZnS is a potential nucleation site for Si *** hardness,tensile strength,and elongation of Al-12Si alloys modified with 17.5%Al-12Si/ZnS powder increase 6.30%,16.18%and 55.45%,respectively,compared to the unmodified Al-12Si *** fracture behavior of the alloy with 17.5wt.%Al-12Si/ZnS powder is dominated by transgranular fracture supplemented by intergranular fracture.

关键词： Al-Si Al-Si/ZnS refinement eutectic silicon

An unprecedented synthesis of axially chiral biaryls by rearrangement and aromatization of carbocations with central-to-axial conversion of chirality

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Science China Chemistry 2024年第9期67卷 2998-3003页

作者： Qi liu Xue-dong li liang cheng li liu Beijing National Laboratory for Molecular Sciences(BNLMS) CAS Key Laboratory of Molecular Recognition and FunctionCAS Research/Education Center for Excellence in Molecular SciencesInstitute of ChemistryChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

The central-to-axial chirality conversion represents a fascinating class of chemical processes consisting of the destruction of stereogenic centers and the simultaneous installation of axial chiral elements,which provides efficient methods for the preparation of axially chiral ***,developing catalytic asymmetric approaches for constructing these central chirality precursors and the efficient central-to-axial chirality conversion remains a challenge due to the requirement of aromatization or elimination *** this work,we have developed an unprecedented enantioselective intramolecular FriedelCrafts alkylation with unactivated-ketone carbonyls from which a chiral tertiary alcohol was generated with high efficiency and excellent *** addition,the central-to-axial chirality conversion strategy has been successfully applied to the synthesis of enantioenriched biaryls via a less-explored carbocation-initiated rearrangement and aromatization under the promotion of Lewis *** methodology provided a straightforward and sustainable access to a broad range of biaryl-2-carboxylic acid and in excellent yields(up to 92%)and excellent central-to-axial chirality conversion(up to 99%conversion percentage).This work could be a great model for developing new methods for synthesizing axially chiral biaryls and a general protocol for the rearrangement and aromatization of carbocations for further functionalization.

关键词： br?nsted acid catalysis desymmetrization phosphoric acid axially chiral biaryls central-to-axial conversion

Controllable synthesis of Tb-based metal-organic frameworks as an efficient fluorescent sensor for Cu^(2+)detection

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Rare Metals 2021年第2期40卷 505-512页

作者： cheng-li dong Ming-Feng li Ting Yang li Feng Ying-Wei Ai Zhang-Lei Ning Meng-Jiao liu Xin Lai Dao-Jiang Gao College of Chemistry and Materials Science Sichuan Normal UniversityChengdu610068China China Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education College of Life SciencesSichuan UniversityChengdu610065China

A series of Tb-based metal-organic frameworks(Tb-MOFs)were successfully synthesized by a solvothermal *** size and morphology of the as-obtained Tb-MOFs can be effectively controlled via regulating the experimental conditions such as the volume fraction of DMF and the molar ratio of Tb^(3+)to *** is found that all the samples exhibit strong green emissions under ultraviolet excitation,corresponding to^(5)D_(4)→^(7)F_(J)transitions of Tb^(3+).Interestingly,Tb-MOFs displayed an efficient and distinct luminescence quenching by Cu^(2+)in aqueous *** competitive fluorescence detection experiments indicate that these Tb-MOFs sensors can be used as a high selective and sensitive sensor of Cu^(2+)detection with the detection limit of 10μmol·L^(-1),which can be used as a promising fluorescence sensor for Cu^(2+)detection in daily life.

关键词： Metal-organic frameworks Controllable synthesis Luminescence Sensor Detection

Spacelike Framed Curves with lightlike Components and Singularities of Their Evolutes and Focal Surfaces in Minkowski 3-space

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Acta Mathematica Sinica,English Series 2024年第6期40卷 1521-1532页

作者： Peng cheng li dong He PEI Xin ZHAO School of Mathematics and Statistics Northeast Normal UniversityChangchun 130024P.R.China Department of Mathematics Harbin Institute of TechnologyWeihai 264209P.R.China School of Mathematics and Statistics Qingdao UniversityQingdao 266071P.R.China

In this paper,we define the evolute and focal surface of a spacelike framed curve with lightlike components in Minkowski *** is a generalization of the previous results of regular spacelike curves,since singularities are allowed in the original spacelike curves studied by spacelike framed curves with lightlike ***,we show a new geometric invariant to characterise singularities of the focal ***,the classification theorem and recognition theorem for the singularities of the focal surface in generic are also given.

关键词： Evolutes focal surfaces spacelike framed curves singularities

Strengthened and toughened SiHfBCN-based hightemperature resistant adhesive with SiC NWs

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Chinese Journal of Aeronautics 2024年第7期37卷 539-549页

作者： Xingang LUAN Xiyue ZHU Xichao dong Min li Laifei cheng Science and Technology on Thermostructural Composite Materials Laboratory Northwestern Polytechnical UniversityXi’an 710072China

To further improve the performance of binders,a SiHfBCN-based high-temperature resistant adhesive was successfully synthesized by Polymer-Derived Ceramics(PDC)route using TiB2,Polysiloxane(PSO)and short SiC nanowires as *** effect of short SiC nanowires on the adhesive strength at room temperature and high temperature,as well as the reinforcing mechanism was *** with the adhesive without SiC nanowires,after curing(at 170℃)and pyrolysis(at 1000℃)in air,the appropriate adding of SiC nanowires upgrades the room temperature and high temperature(at 1000℃ in air)adhesive strength to(12.50±0.67)MPa(up by about 32%)and(13.11±0.79)MPa(up by about 106%),***,under the synergistic impact of the nanowire bridging,nanowire breaking,nanowire drawing and crack deflection,the optimized adhesive exhibits multi-stage fracture,causing the increscent fracture displacement.

关键词： High-temperature resistant adhesive SiHfBCN SiC NWs Strengthening Toughening

Microstructure and mechanical properties of magnesium matrix composite reinforced with carbon nanotubes by ultrasonic vibration

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Rare Metals 2022年第7期41卷 2331-2336页

作者： cheng-dong li Xiao-Jun Wang Wei-Qing liu Ku Wu Hai-Long Shi Chao Ding Ming-Yi Zheng School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China

A novel approach was successfully developed to fabricate bulk carbon nanotube-reinforced Mg matrix com-posites with uniform carbon nanotubes(CNTs).The approach consists of pre-dispersion and ultrasonic ***-neous and single CNTs on flake Zn powder can be achieved simply by slurry *** pre-dispersed CNTs were added to Mg melt,and then,the melt was ultrasonically *** ultrasonic vibration,the CNTs/Mg-6Zn melt was cast into a metal *** CNTs distribute homoge-neously and singly in the bulk ***,good interfacial bonding is achieved,and Raman spectroscopy analysis shows that the damage to CNTs is ***,CNTs evidently improve the ultimate tensile strength,yield strength and *** Kelly-Tyson formula agrees well with the experimental tensile value,and the load-transfer efficiency is nearly equal to 1.

关键词： Magnesium matrix composite Carbon nanotubes Ultrasonic vibration Microstructure Mechanical properties