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Phonon broadening in high entropy alloys

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npj Computational Materials 2017年第1期3卷 154-162页

作者： fritz Kormann Yuji Ikeda Blazej Grabowski marcel h.f.sluiter Materials Science and Engineering Delft University of Technology2628 CD DelftThe Netherlands Center for Elements Strategy Initiative for Structural Materials Kyoto UniversityKyoto 606-8501Japan Computationals Materials Design Max-Planck-Institut fur Eisenforschung GmbH40237 DusseldorfGermany

Refractory high entropy alloys feature outstanding properties making them a promising materials class for next-generation hightemperature *** high temperatures,materials properties are strongly affected by lattice vibrations(phonons).Phonons critically influence thermal stability,thermodynamic and elastic properties,as well as thermal *** contrast to perfect crystals and ordered alloys,the inherently present mass and force constant fluctuations in multi-component random alloys(high entropy alloys)can induce significant phonon scattering and *** their importance,phonon scattering and broadening have so far only scarcely been investigated for high entropy *** tackle this challenge from a theoretical perspective and employ ab initio calculations to systematically study the impact of force constant and mass fluctuations on the phonon spectral functions of 12 body-centered cubic random alloys,from binaries up to 5-component high entropy alloys,addressing the key question of how chemical complexity impacts *** find that it is crucial to include both mass and force constant *** one or the other is neglected,qualitatively wrong results can be obtained such as artificial phonon band *** analyze how the results obtained for the phonons translate into thermodynamically integrated quantities,specifically the vibrational *** in the vibrational entropy with increasing the number of elements can be as large as changes in the configurational entropy and are thus important for phase stability *** set of studied alloys includes MoTa,MoTaNb,MoTaNbW,MoTaNbWV,VW,VWNb,VWTa,VWNbTa,VTaNbTi,VWNbTaTi,hfZrNb,hfMoTaTiZr.

关键词： alloys entropy high

Thick and Dense Anodic Oxide Layers formed on Aluminum in Sulphuric Acid Bath

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Journal of Materials Science & Technology 2010年第2期26卷 113-118页

作者： W. Bensalah M. feki M. Wery h.f. Ayedi URCIM Department of Materials EngineeringNational School of Engineering IUT Orsay-Paris XI University Plateau du Moulon URCIM Department of Materials Engineering National School of Engineering

Thick and dense oxide layers were obtained on aluminium in sulphuric acid electrolyte. for this purpose, the methodology of experimental design was used. A three-variables Doehlert design （bath temperature, anodic current density, sulphuric acid concentration）, was achieved. In order to maximize the growth rate and the density of the anodic oxide layer, optimum path study was conducted. Under the determined optimal anodizing conditions （5.7℃, 3 ***-2,Csul=140 g.L-1）, the estimated response values were 0.86 μmin-1 and 3.12 ***-2 for growth rate and density, respectively. The morphology of optimum layer was examined by scanning electron microscopy （SEM）. The compactness of the optimum anodic layer can be correlated with its morphology revealed by SEM observations.

关键词： Sulphuric anodization Experimental design Growth rate Density

ACTIVATION Of Tife-LaNi_5 COMPOUND PARTICLES

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Acta Metallurgica Sinica(English Letters) 1997年第2期10卷 131-133页

作者： h.f. Zhang M.Q. Lu W. Li State Key Laboratory of RSA Institute of Metal Research Chinese Academy of Sciences Shenyang 110015 China Shenyang Institute of Technology Shenyang 110015 China

Through controlled mechanical alloying treatment, Tife and LaNi5 particles combined together on the surface of Tife. This kind of compound particles can be easily activated at room temperature and an h2-pressure of 4.0 MPa. LaNi5 particles provided 'window' and 'path' for entrance of hydrogen from the surface to the interior of Tife alloy.

关键词： Tife-LaNi_5 compound particle activation mechanical alloying

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A taste for honey

A taste for honey

Synthesis and Characterization of fe_(50)Cr_(14)Mo_(14)C_(14)B_6Gd_2 Bulk Amorphous Steel

作者： h.f. heard

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Journal of Materials Science & Technology 2010年第9期26卷 783-786页

作者： M. Iqbal J.I. Akhter h.f. Zhang Z.Q. hu Physics Division Pakistan Institute of Nuclear Science &: Technology P.O. Nilore Islamabad Pakistan Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of SciencesShenyang 110016 China

Bulk amorphous steel having 7 mm thickness was synthesized to evaluate its thermal stability and mechanical *** steel was synthesized by Cu mold casting technique using 1-2N pure *** of the material was done by X-ray diffraction,differential scanning calorimetry and scanning electron *** activation energies were calculated by Kissinger equation and it was found that the steel had better stability against *** properties like Vicker s hardness,nanohardness,elastic modulus and elastic recovery of as-cast and annealed samples were *** was concluded that the present steel had good glass-forming ability（GfA） and mechanical properties.

关键词： Bulk amorphous steels Activation energy Glass-forming ability Mechanical properties

Mechanical and Abrasive Wear Properties of Anodic Oxide Layers formed on Aluminium

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Journal of Materials Science & Technology 2009年第4期25卷 508-512页

作者： W. Bensalah K. Elleuch M. feki M. Wery h.f. Ayedi Unit'e de Recherche de Chimie Industrielle et Mat'eriaux(URCIM) Departement of Materials EngineeringNational School of Engineering IUT Orsay-Paris XI University

Aluminium oxide coatings were formed on aluminium substrates in oxalic acid-sulphuric acid bath. Abrasion tests of the obtained anodic layers were carried out on a pin-on-disc machine in accordance with the ISO/DP 825 specifications. The rickets microhardness, D （hV0.2）, and the abrasion weight loss, Wa （mg） were measured. Influence of oxalic acid concentration （Cox）, bath temperature （T） and anodic current density （J） on D and Wa has been examined, and the sulphuric acid concentration （Csul） was maintained at 100 g.L-1. It was found that high microhardness and abrasive wear resistance of oxide layers were produced under low temperatures and high current densities with the addition of oxalic acid. The morphology and the composition of the anodic oxide layer were examined by scanning electron microscopy （SEM）, atomic force microscopy （AfM）, optical microscopy and glow-discharge optical emission spectroscopy （GDOES）. It was found that the chemistry of the anodizing electrolyte, temperature, and current density are the controlling factors of the mechanical properties of the anodic oxide layer.

关键词： Aluminium oxide Vickers microhardness Abrasive wear

TiZr-base Bulk Metallic Glass with over 50 mm in Diameter

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Journal of Materials Science & Technology 2010年第6期26卷 481-486页

作者： M. Q. Tang h.f. Zhang Z. W. Zhu h.M. fu A.M. Wang h. Li Z.Q. hu Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences 72Wenhua Road Shenyang 110016 China

Low-cost TiZr-base bulk metallic glasses （BMGs）（Ti36.1Zr33.2Ni5.8Be24.9）100-xCux （x=5, 7 and g） with a maximum size of over 50 mm in diameter were developed by optimizing the alloy composition. The idea is initiated by selecting a particular microstructure comprising primary β-Ti dendrite and amorphous phase. Afterwards, based on this composition of amorphous phase, a class of TiZr-base bulk metallic glasses was designed step by step to reach the optimum composition range. The glass transition temperature （Tg）, initial crystallization temperature （Tx） and width of supercooled region （AT） of （***33.2Nis.8Be24.9）91Cu9 BMG are 611, 055 and 44 K, respectively. The （Ti36.1Zr33.2Ni5.8Be24.9）91Cu9 BMG exhibits low density of 5.541 g·cm-3 and high compressive fracture strength of 1800 MPa, which promises the potential application as structural materials.

关键词： TiZr-base alloy Bulk metallic glass (BMG) fracture strength

REVISED k-ε TURBULENCE MODEL IN ELECTROMAGNETIC CONTINUOUS CASTING Of MELT

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Acta Metallurgica Sinica(English Letters) 2003年第5期16卷 395-400页

作者： h.f. huo and B.K. LiDepartment of Thermal Engineering, School of Materials and Metallurgy, Northeastern University, Shenyang 110004, China. Dept. of Thermal Eng. Sch. of Mat. and Metall. Northeastern Univ. Shenyang 110004 China

The research is motivated by the ongoing the electromagnetic continuous casting of molten metal. The revised k-ε model considering the effect of magnetic field application was derived. The specific model equations for the electromagnetic braking were used to calculate the velocity distribution in the continuous casting mold of steel. The results show that the revised k-ε model considering the effect of magnetic field application tends to suppress the production of turbulence and difference between the conventional and revised k-e model is small.

关键词： revised k-ε turbulence model electromagnetic continuous casting magnetic field

Image Content-based Watermarking Resistant against Geometrical Distortions

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Image Content-based Watermarking Resistant against Geometric...