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Effect of melt cooling rate on glass transition kinetics and structural relaxation of Vit1 metallic glass

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China Foundry 2021年第2期18卷 118-123页

作者： Wei Zhang Qing-chun Xiang Ying-dong Qu Qing-feng Li Ying-lei Ren Ke-qiang Qiu School of Materials Science and Engineering Shenyang University of TechnologyShenyang 110870China

The thin ribbons and the bulk cylindrical rods with diameters of 2 mm and 10 mm of the Vit1 metallic glass(MG)were prepared by the single roller melt spinning method and the copper mold injection casting method,*** cooling rates of the samples during melt solidification were *** glass transition behaviors of three groups of MG samples with different solidification cooling rates were studied by differential scanning calorimetry(DSC)at different heating *** effects of melt cooling rate on the glass transition kinetic parameters such as apparent activation energy(E)and fragility parameter(m)of the Vit1 MG were studied using the Kissinger and the Vogel-Fulcher-Tammann(VFT)***,the structural relaxation enthalpy(ΔHrel)of three groups of MG samples was quantitatively analyzed by DSC through multi-step temperature rise and fall *** show that the melt cooling rate(R)has a significant effect on the glass transition kinetics and the structural relaxation of the Vit1 *** R decreases in the order of magnitude,the glass transition temperature(Tg),E,m,andΔHrel of the Vit1 MG gradually ***,in the range of the experimental cooling rates,E,m,andΔHrel all have an approximately linear relationship with lgR.

关键词： glass transition structural relaxation apparent activation energy fragility parameter cooling rate Vit1 metallic glass

Preparation of polymer nanoparticles,and the effect of nanoconfinement on glass transition,structural relaxation and crystallization

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Frontiers of Chemistry in China 2011年第4期6卷 332-340页

作者： Rong CHEN Dinghai HUANG Tianjin Key Laboratory of Composite and Functional Materials School of Materials Science and EngineeringTianjin UniversityTianjin300072China

In this review the preparation methods of polymer nanoparticles from chemical microemulsion polymerization to physical methods such as spray-drying,freeze-drying,freeze-extracting,fast evaporation and spreading evaporation have been *** influence of nanoconfinement on glass transition temperature(T_(g))variation from significant or slight decrease,no evident T_(g) deviation,to even T_(g) increase,as well as possible explanations of T_(g) deviations were *** influences of nanoconfinement or entanglement on the other properties such as structural relaxation,crystallization in polymer nanoparticle samples were also reviewed in this article.

关键词： conﬁnement nanoparticles glass transition structural relaxation crystallization

The effect of polyvinylpyrrolidone addition on microstructure,surface aspects,the glass transition temperature and structural strength of honey and coconut sugar powders

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Journal of Future Foods 2022年第4期2卷 338-345页

作者： Valentyn A.Maidannyk Vinay S.N.Mishra Song Miao Mohamad Djali Noel McCarthy Bambang Nurhadi Food Chemistry and Technology Department Teagasc Food Research CentreMooreparkFermoy P61 C996Ireland Department of Food Industrial Technology Faculty of Agro-Industrial TechnologyUniversitas PadjadjaranBandung 40600Indonesia Study Centre of Agric.Technology Development Faculty of Agric.Industrial TechnologyUniversitas PadjadjaranBangung 40600Indonesia

Deep knowledge of the microstructure and physicochemical properties of polymeric food systems,such as honey powders(HP)and coconut sugars(CS),has practical importance for industry and end *** study investigated the effect of polyvinylpyrrolidone(PVP)addition on microstructure,roughness,glass transition,α-relaxation temperatures and structural strength(S)of anhydrous complex carbohydrates *** addition of PVP slightly increased the glass transition andα-relaxation temperature for HP and CS systems as high molecular weight *** with PVP addition showed“stronger”behaviour according to the S *** light,scanning electron and atomic force microscopies showed slight differences in transparency and shapes between controls and systems with PVP *** morphological changes and roughness were investigated in this study to provide insight into HP and CS particles’structural ***,S-involved structural diagrams were built to determine S parameters for controlling the structural transformation of HP and CS systems with and without PVP *** results obtained in this work provide new information on polymer-carbohydrate interactions in complex food systems and structural transformations during their production and storage.

关键词： Honey powder Coconut sugar powder structural strength Scanning electron microscopy Atomic force microscopy Glass transition structural relaxation

Numerical Simulation of Stress Field in Physical Tempering Process of Flat Soda Lime Silica Glass

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Journal of Wuhan University of Technology(Materials Science) 2023年第1期38卷 20-30页

作者：刘超英 HE Dongsheng OU Yingchun HE Feng HAO Lizi XU Shaokun MA Juanrong China Building Materials Academy Beijing 100024China School of Materials Science and Engineering Wuhan University of TechnologyWuhan 430070China China Helicopter Research and Development Institute Jingdezhen 333001China

Based on the analysis of different theory for glass tempering process,the“structural theory”with stress relaxation and structural relaxation effects was selected to investigate the tempering of flat glass *** geometrical model with small size and non-homogeneous mesh were considered to build the finite element models according to the characteristics of stress *** tempering process of flat glass with12 mm thickness was calculated with the verified finite element *** transient and permanent stress of the central area,edge and corner end of the flat glass are obtained and *** the calculation results of basic case,the transient tensile stress at the upper surface of the central area,the center point of edge,the edge of edge,the edge of corner were 14.30,18.94,40.76 and 34.75 MPa,*** transient tensile stress at these points were dangerous to promote the glass to break during the *** addition,the point at the diagonal line of symmetry plane in the thickness direction,which is 14 mm from corner,has the maximum permanent tensile stress about 70.01 MPa in the flat glass after ***,it is indicated that the corner is the weakest region in the tempered glass.

关键词： nite element tempering stress relaxation structural relaxation compressive stress tensile stress

Uncovering the internal structure of five-fold twinned nanowires through 3D electron diffraction mapping

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Chinese Physics B 2020年第6期29卷 517-531页

作者： Xin Fu GRINM Group Corporation Limited National Analysis and Testing Center for Nonferrous Metals and Electronic MaterialsBeijing 101400China Guobiao(Beijing)Testing&Certification Co. Ltd.Beijing 101400China China United Test&Certification Co. Ltd.Beijing 101400China General Research Institute for Nonferrous Metals Beijing 100088China

Five-fold twinned nanostructures are intrinsically strained or relaxed by extended defects to satisfy the space-filling *** both of metallic and semiconductor five-fold twinned nanostructures show inhomogeneity in their cross-sectional strain distribution,the evident strain concentration at twin boundaries in the semiconductor systems has been found in contrast to the metallic ***,a problem is raised how the chemical bonding characteristics of various five-fold twinned nanosystems affects their strain-relieving defect *** using three-dimensional(3D)electron diffraction mapping methodology,the intrinsic strain and the strain-relieving defects in a pentagonal Ag nanowire and a star-shaped boron carbide nanowire,both of them have basically equal radial twin-plane width about 30 nm,are nondestructively *** non-uniform strain and defect distribution between the five single crystalline segments are found in both of the five-fold twinned *** intensity fine structure analysis for the boron carbide five-fold twinned nanowire indicates the presence of high-density of planar defects which are responsible for the accommodation of the intrinsic angular ***,for the Ag five-fold twinned nanowire,the star-disclination strain field is still present,although is partially relieved by the formation of localized stacking fault layers accompanied by partial *** analysis suggests that the variety in the strain-relaxation ways for the two types of five-fold twinned nanowires could be ascribed to the large difference in shear modulus between the soft noble metal Ag and the superhard covalent compound boron carbide.

关键词： five-fold twinnining elastic strain structural relaxation electron diffraction mapping

First-principles study of bulk and (001) surface of TiC

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Transactions of Nonferrous Metals Society of China 2010年第5期20卷 857-862页

作者：房立红王丽宫建红戴洪尚苗德壮 Key Laboratory of Liquid Structure and Heredity of Materials Ministry of EducationShandong University School of Mechanical and Electronic Engineering Shandong University at Weihai

The structural and electronic properties of bulk and (001) plane of TiC were investigated by the first-principles total-energy pseudopotential method based on density functional *** calculated bulk properties indicate that bonding nature in TiC is a combination of ionicity,covalency and metallicity,in which the Ti-C covalent bonding is the predominate *** calculated results of structural relaxation and surface energy for TiC(001) slab indicate that slab with 7 layers shows bulk-like characteristic interiors,and the changes of slab occur on the outmost three layers,which shows that the relaxation only influences the top three ***,the strong Ti-C covalent bonding can be found in the distribution of charge density on the (110) and (001) ***-C covalent bonding is enhanced by the charge depletion and accumulation in the vacuum and the interlayer region between top two atomic layers.

关键词： first-principles TiC charge transfer structural relaxation

Compression Behaviour of Ni77P23 Amorphous Alloy up to 30.5 GPa

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Chinese Physics Letters 2005年第10期22卷 2615-2617页

作者：李工张新宇孙懿楠钱煜青刘景刘日平 Key Laboratory of Aletastable Materials Science and Technology Yanshan University Qinhuangdao 066004 BSRF Institute of High Energy Physics Chinese Academy of Sciences Beijing 100039

The compression behaviour of Ni77P23 amorphous alloy is investigated at room temperature in a diamond-anvil cell instrument using in-situ high pressure energy dispersive x-ray diffraction with a synchrotron radiation source. The equation of state is determined by fitting the experimental data according to the Birch-Murnaghan equation. It is found that the structure of Ni77P23 amorphous alloy is stable under pressures up to 30.5 GPa. Within the pressure range from zero to the experimental one, the pressure-induced structural relaxation is reversible.

关键词： BULK METALLIC-GLASS structural relaxation HIGH-PRESSURE SUPERCOOLEDLIQUID CRYSTALLIZATION

Thermal effects and evolution of the defect concentration based on shear modulus relaxation data in a Zr-based metallic glass

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Chinese Physics B 2020年第8期29卷 133-136页

作者： Qi Hao Ji-Chao Qiao E V Goncharova G V Afonin Min-Na Liu Yi-Ting Cheng V A Khonik School of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi'an 710072China Department of General Physics Voronezh State Pedagogical UniversityLenin Street 86Voronezh 394043Russia

A relationship between thermal effects and relaxation of the high-frequency shear modulus upon heat treatment of bulk Zr48(Cu5/6Ag1/6)44Al8 metallic glass is *** relationship is attributed to the relaxation of a interstitial-type defect system frozen-in from the melt upon glass *** data show that thermal effects occurring on heating include heat release below the glass transition temperature,heat absorption above it and heat release caused by *** equation derived within the Interstitialcy theory can be used to calculate the shear modulus relaxation using the calorimetric *** obtained results are used to trace the defect concentration as functions of temperature and thermal prehistory.

关键词： shear modulus metallic glass structural relaxation interstitialcy theory

Density Functional Theory for the Investigation of Catalytic Activity of X@Cu_(12)(X = Cu, Ni, Co, or Fe) for N_2O Decomposition

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Chinese Journal of structural Chemistry 2015年第6期34卷 822-836页

作者： YU Wei-Ling ZUO Hui-Wen LU Chun-Hai LI Yi ZHANG Yong-Fan CHEN Wen-Kai Department of Chemistry Fuzhou University College of Nuclear Technology and Automation Engineering Chengdu University of Technology Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry (FTCC) Xiamen University

We have investigated the reaction mechanism for N20 decomposition on Cu13 via density functional theory. It is found that N20 decomposition on the cluster is more prone to be along the Eley-Rideal （ER） pathway in comparison with the Langmuir-Hinshelwood （LH） channel. There exists structural relaxation for Cu13 cluster in the reaction, which may influence the catalytic activity of cluster for the subsequent N2O decomposition. The core atom in the Cu13 cluster is substituted with the Fe, Co, or Ni to enhance structural stability and prevent from the obvious configuration relaxation in the reaction. Note that these bimetallic clusters are of icosahedra as the Cu13. They have activities for N2O dissociation along ER pathway and the heteroatorn in the cluster can prevent configuration from relaxation. Finally, the Ni@Cu12 cluster can be as a superior catalyst in a complete catalytic cycle via comparison in this study.

关键词： bimetallic cluster reaction mechanism catalytic activity nitrous oxide decomposition structural relaxation