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Effect of environments and normal loads on tribological properties of nitrided Ni(45)(FeCoCr)(40)(AlTi)(15)high-entropy alloys

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journal of Materials Science & Technology 2020年第7期42卷 85-96页

作者： L.W.Lan X.j.Wang R.p.Guo H.j.Yang j.W.Qiao Research Center for High-Entropy Alloys College of Materials Science and EngineeringTaiyuan University of TechnologyTaiyuan030024China

The tribological properties of nitrided Ni(45)(FeCoCr)(40)(AlTi)(15)high-entropy alloys(HEAs)were investigated in air and simulated acid rain under different normal loads(5,7,10,and 12 N)at ambient *** results revealed that as-cast HEAs were only composed of FCC phase,while the volume fraction of FCC phase in the nitrided alloys was significantly ***,the hard phases of AIN,CrN,Fe4 N,and TiN phases were formed in the nitrided *** thickness of the nitriding layer was about 8.4μ*** hardness increased from 8.7 Gpa in as-cast alloys to 14.5 Gpa in the nitrided *** addition,under the same conditions,the friction coefficient of the nitrided alloys was higher than that of as-cast alloys,but the wear rate was generally lower than that of as-cast ***,the wear rate of the nitrided alloys was the lowest in acid rain due to the lubrication,cleaning,and cooling in the liquid *** air,dominating wear mechanisms in as-cast and nitrided alloys were abrasive,delamination,and adhesive ***,the wear mechanism of as-cast and nitrided alloys in acid rain was mainly abrasive and corrosion wears.

关键词： Abrasive wear Hardness Corrosive wear Microstructure Wear mechanism

The effect of temperature on load partitioning evolution in magnesium metal matrix composite reinforced with Ti particles using in-situ synchrotron radiation diffraction experiments

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journal of Magnesium and Alloys 2023年第2期11卷 706-719页

作者： G.Garces j.Medina p.perez A.Stark N.Schell p.Adeva Department of physical Metallurgy CSICAvenida Gregorio del Amo 8Madrid E-28040Spain Institute of Materials physics Helmholtz-Zentrum HereonMax-Planck-Str.1Geesthacht 21502Germany

The load partitioning between the magnesium and titanium phases in an extruded Mg-15%Ti(vol.%) composite from room temperature up to 300 ℃ using synchrotron radiation diffraction during in-situ compression tests. During compression, the magnesium matrix composite deforms mainly by the activation of the extension twinning system up to 200 ℃. The volume fraction of twins increases with the plastic strain but decrease with the compression temperature. Hard titanium particles bear an additional load transferred by the soft magnesium matrix from room temperature up to 300 ℃. This effect is amplified after yield stress during plastic deformation. Additionally, twins within magnesium grains behaves as an additional reinforcement at low temperature(below 200 ℃) inducing an increase in the work hardening of the composite.

关键词： Magnesium alloys In-situ synchrotron radiationdiffraction plasticity precipitation Dislocationslip Twinning

FTIR Studies on NO Adsorption on [Co+Mg(Sr)] /ZSM-5

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Chemical Research in Chinese Universities 2002年第4期18卷 389-392页

作者： LEE C. W. CHONG p. j. KRICT Taejon 305-606 KoreaKRICT Taejon 305-606 Korea

The adsorption of NO on /ZSM-5 zeolites with different contents was studied by means of FTIR spectroscopy. The dominant NO species adsorbed on /ZSM-5 was found to be in a dinitrosyl form, as demonstrated by the IR bands at 1 813 and 1 896 cm -1. NO was adsorbed in a mononitrosyl form as shown in the region of 1 937-1 939 cm -1 as a minor species. Samples /ZSM-5 showed a new band near 1 858 cm -1(w) attributable to the species of Co_3O_4-NO. It was found that zeolite /ZSM-5 exhibits superior performance characteristics for SCR of NO molecules, and is promising as a useful catalyst. The typical catalyst /ZSM-5 for SCR resulted from the collaboration of the metal alkalinity and the ionic radius of the metal(such as Mg or Sr).

关键词： Infrared spectroscopy Nitric oxide Adsorption Mononitrosyl Dinitrosyl Cobalt oxide

Glass-forming Ability and Corrosion Resistance of Zr—Cu—Al—Co Bulk Metallic Glass

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journal of Materials Science & Technology 2016年第4期32卷 349-354页

作者： W.Zhou W.p.Weng j.X.Hou Shagang School of Iron and Steel Soochow University

Investigations were carried out to examine the effects of Co addition on the glass-forming ability （GFA） and corrosion resistance of Zr46Cu46AI8 bulk metallic glass in chloride-containing solution. It is found that the GFA of （Zr46Cu46Al8）100-xCox （x = 0, 1, 2, and 4 at.%） alloys reduces with the increase in Co content and correlates well with the parameters, such as the supercooled liquid region width ATx, the reduced glass transition temperature Trg and γ. The corrosion resistance is however found to be enhanced with the in- crease in Co concentration. The addition of Co causes the enrichment of Zr and Al, but depletes Cu in the surface films, which effectively enhances the corrosion potential and lowers the corrosion current density.

关键词： Bulk metallic glassCo-additionGlass-forming abilityCorrosion resistance

Simplified seismic performance assessment and implications for seismic design

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Earthquake Engineering and Engineering Vibration 2014年第S1期13卷 95-122页

作者： Timothy j.Sullivan David p.Welch Gian Michele Calvi University of pavia Department of Civil Engineering & ArchitecturePavia 27100Italy European Centre for Training and Research in Earthquake Engineering Pavia 27100Italy UME School ROSE ProgrammeIUSS Pavia phD candidate IUSS pavia professor

The last decade or so has seen the development of refined performance-based earthquake engineering(pBEE) approaches that now provide a framework for estimation of a range of important decision variables,such as repair costs,repair time and number of casualties. This paper reviews current tools for pBEE,including the pACT software,and examines the possibility of extending the innovative displacement-based assessment approach as a simplified structural analysis option for performance assessment. Details of the displacement-based s+eismic assessment method are reviewed and a simple means of quickly assessing multiple hazard levels is proposed. Furthermore,proposals for a simple definition of collapse fragility and relations between equivalent single-degree-of-freedom characteristics and multi-degree-of-freedom story drift and floor acceleration demands are discussed,highlighting needs for future research. To illustrate the potential of the methodology,performance measures obtained from the simplified method are compared with those computed using the results of incremental dynamic analyses within the pEER performance-based earthquake engineering framework,applied to a benchmark building. The comparison illustrates that the simplified method could be a very effective conceptual seismic design tool. The advantages and disadvantages of the simplified approach are discussed and potential implications of advanced seismic performance assessments for conceptual seismic design are highlighted through examination of different case study scenarios including different structural configurations.

关键词： performance-based earthquake engineering displacement-based assessment seismic assessment

Fundamental Gaps in Numerical Semigroups with Respect to Their Multiplicity

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Acta Mathematica Sinica,English Series 2004年第4期20卷 629-646页

作者： j.C.ROSALES p.A.GARCíA-SANCHEZ j.I.GARCíA-GARCíA j.A.jIMENEZMADRID DepartamentodeAlgebra UniversidaddeGranadaE-18071GranadaSpain InstitutodeAstrofisicadeAndalucia(CSIC) ApartadoPostal300418080GranadaSpain

For a numerical semigroup,we introduce the concept of a fundamental gap with respect to the multiplicity of the *** semigroup is fully determined by its multiplicity and these gaps. We study the case when a set of non-negative integers is the set of fundamental gaps with respect to the multiplicity of a numerical *** semigroups with maximum and minimum number of this kind of gaps are described.

关键词： Numerical semigroup Gap Multiplicity Frobenius number

Assessment of oxide nanoparticle stability in liquid phase transmission electron microscopy

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Nano Research 2019年第9期12卷 2355-2363页

作者： Mark j. Meijerink Krijn p. de jong jovana Zecevic Inorganic Chemistry and Catalysis Debye Institute of Nanomaterials ScienceUtrecht UniversityUniversiteitsweg 993584 CG UtrechtThe Netherlands

Studying liquid phase nanoscale dynamic processes of oxide nanoparticles is of considerable interest to a wide variety of *** developed liquid phase transmission electron microscopy(Lp-TEM)is a promising technique,but destabilization of oxides by solid-liquid?electron interactions remains an important *** this work we present a methodology to assess Lp-TEM oxide stability in an aqueous phase,by subjecti ng several oxides of tech no logical importa nee to a controlled electr on dose in *** show a correlati on based on the Gibbs free en ergy of oxide hydrati on that can be used to assess the stability of oxides and dem on strate the existenee of several remarkably stable oxides,with no observable structural changes after one hour of electron beam irradiation in *** such destabilization phenomena combined with the identification of stable oxides allows for designing Lp-TEM experiments free from adverse beam effects and thus in vestigati ons of numerous releva ntnano scale processes in water.

关键词： liquid phase transmission electron microscopy(Lp-TEM) transmission electron microscopy electron beam damage metal oxide nano materials oxide stability

A rule-free workflow for the automated generation of databases from scientific literature

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npj Computational Materials 2023年第1期9卷 96-109页

作者： Luke p.j.Gilligan Matteo Cobelli Valentin Taufour Stefano Sanvito School of physics AMBER and CRANN InstituteTrinity CollegeDublin 2DublinIreland Department of physics and Astronomy University of CaliforniaDavisCA 95616USA

In recent times,transformer networks have achieved state-of-the-art performance in a wide range of natural language processing *** we present a workflow based on the fine-tuning of BERT models for different downstream tasks,which results in the automated extraction of structured information from unstructured natural language in scientific *** to existing methods for the automated extraction of structured compound-property relations from similar sources,our workflow does not rely on the definition of intricate grammar ***,it can be adapted to a new task without requiring extensive implementation efforts and *** test our data-extraction workflow by automatically generating a database for Curie temperatures and one for band *** are then compared with manually curated datasets and with those obtained with a state-of-the-art rule-based ***,in order to showcase the practical utility of the automatically extracted data in a material-design workflow,we employ them to construct machine-learning models to predict Curie temperatures and band *** general,we find that,although more noisy,automatically extracted datasets can grow fast in volume and that such volume partially compensates for the inaccuracy in downstream tasks.

关键词： automated rule adapted

Effect of compressibility on the hypervelocity penetration

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Acta Mechanica Sinica 2018年第1期34卷 82-98页

作者： W.j.Song X.W.Chen p.Chen Department of Mechanics and Engineering Science College of Engineering Peking University Advanced Research Institute for Multidisciplinary Science Beijing Institute of Technology The State Key Lab of Explosion Science and Technology Beijing Institute of Technology Centre for Applied physics and Technology (CApT) Peking University

We further consider the effect of rod strength by employing the compressible penetration model to study the effect of compressibility on hypervelocity ***, we define different instances of penetration efficiency in various modified models and compare these penetration efficiencies to identify the effects of different factors in the compressible model. To systematically discuss the effect of compressibility in different metallic rod-target combinations, we construct three cases, i.e., the penetrations by the more compressible rod into the less compressible target, rod into the analogously compressible target, and the less compressible rod into the more compressible target. The effects of volumetric strain, internal energy, and strength on the penetration efficiency are analyzed simultaneously. It indicates that the compressibility of the rod and target increases the pressure at the rod/target interface. The more compressible rod/target has larger volumetric strain and higher internal energy. Both the larger volumetric strain and higher strength enhance the penetration or anti-penetration ability. On the other hand, the higher internal energy weakens the penetration or anti-penetration ability. The two trends conflict, but the volumetric strain dominates in the variation of the penetration efficiency, which would not approach the hydrodynamic limit if the rod and target are not analogously compressible. However, if the compressibility of the rod and target is analogous, it has little effect on the penetration efficiency.

关键词： Compressibility Hypervelocity penetration Equation of state(EOS) Shockwave Bernoulli equation