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Now showing items 145 - 160 of 33812

  • Producing Fe–W–Co–Cr–C Alloy Cutting Tool Material Through Powder Metallurgy Route

    Datta Banik, Bibhas; Dutta, Debasish; Ray, Siddhartha  

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  • Reaction path in formation of Ti 1?x W x C solid solution by combustion synthesis

    Liu, Guanghua   Yang, Zengchao   Li, Jiangtao   He, Gang   Chen, Yixiang   Chen, Kexin   Fan, Dingdong  

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  • Producing Fe–W–Co–Cr–C Alloy Cutting Tool Material Through Powder Metallurgy Route

    Datta Banik, Bibhas   Dutta, Debasish   Ray, Siddhartha  

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  • Self-Assembly and Ordering of C(60) on the WO(2)/W(110) Surface

    Krasnikov, Sergey A.   Bozhko, Sergey I.   Radican, Kevin   Luebben, Olaf   Murphy, Barry E.   Vadapoo, Sundar-Raja   Wu, Han-Chun   Abid, Mohamed   Semenov, Valery N.   Shvets, Igor V.  

    The growth and ordering of C(60) molecules on the WO(2)/W(110) surface have been studied by low-temperature scanning tunnelling microscopy and spectroscopy (STM and STS), low-energy electron diffraction (LEED), and density functional theory (DFT) calculations. The results indicate the growth of a well-ordered C(60) layer on the WO(2)/W(110) surface in which the molecules form a close-packed hexagonal structure with a unit cell parameter equal to 0.95 nm. The nucleation of the C(60) layer starts at the substrate's inner step edges. Low-temperature STM of C(60) molecules performed at 78 K demonstrates well-resolved molecular orbitals within individual molecules. In the C(60) monolayer on the WO(2)/W(110) surface, the molecules are aligned in one direction due to intermolecular interaction, as shown by the ordered molecular orbitals of individual C(60). STS data obtained from the C(60) monolayer on the WO(2)/W(110) surface are in good agreement with DFT calculations.
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  • Sintered (Ti,W)C carbides

    Jung, J.   Kang, S.  

    Sintered (Ti,W)C carbides were prepared from (Ti,W)C solid solution powder at 1510 degrees C. The powder was produced by milling a mixture of carbon and oxides and then reducing it at 1200 degrees C for 1 h. The sintered (Ti,W)C carbides demonstrate full density, excellent hardness and fracture toughness values (rho: 98-100%, HVN: 19-21 GPa, K-IC: 6.4-7.7 MPa m(1/2)). These homogeneous (Ti,W)C carbides have considerable potential for use in structural applications. (c) 2007 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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  • Sintered (Ti,W)C carbides

    J. Jung   S. Kang  

    Sintered (Ti,W)C carbides were prepared from (Ti,W)C solid solution powder at 1510degC. The powder was produced by milling a mixture of carbon and oxides and then reducing it at 1200degC for 1h. The sintered (Ti,W)C carbides demonstrate full density, excellent hardness and fracture toughness values ( rho: 98-100%, HVN: 19-21GPa, KIC: 6.4-7.7MPam 1/2). These homogeneous (Ti,W)C carbides have considerable potential for use in structural applications. [All rights reserved Elsevier]
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  • Microstructure of (W,Ti)C–Co system containing platelet WC

    Hyomoon Nam   Jaehyuk Lim   Shinhoo Kang  

    (W1−xTix)C–10Co cermets consist of two phases, hcp (W,Ti)C and fcc (Ti,W)C. The hcp (W,Ti)C exhibits thin platelet morphology. The (1 0 1) prism plane was developed preferentially in (W,Ti)C powder and the platelet grew via dissolution/precipitation during sintering. The morphology is found effective in enhancing the toughness of the system.
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  • In situ study of self-ion irradiation damage in W and W-5Re at 500 degrees C

    Yi, X.   Jenkins, M. L.   Briceno, M.   Roberts, S. G.   Zhou, Z.   Kirk, M. A.  

    In situ self-ion irradiations (150keVW(+)) have been carried out on W and W5Re at 500 degrees C, with doses ranging from 10(16) to 10(18) W(+)m(2) (approximate to 1.0dpa). Early damage formation (10(16)W(+)m(2)) was observed in both materials. Blackwhite contrast experiments and image simulations using the TEMACI software suggested that vacancy loops were formed within individual cascades, and thus, the loop nucleation mechanism is likely to be cascade collapse'. Dynamic observations showed the nucleation and growth of interstitial loops at higher doses, and that elastic loop interactions may involve changes in loop Burgers vector. Elastic interactions may also promote loop reactions such as absorption or coalescence or loop string formation. Loops in both W and W5Re remained stable after annealing at 500 degrees C. One-dimensional hopping of loops (b=1/2 111>) was only seen in W. At the final dose (10(18)W(+)m(2)), a slightly denser damage microstructure was seen in W5Re. Both materials had about 34x10(15) loops m(2). Detailed post-irradiation analyses were carried out for loops of size4nm. Both b=1/2 111 (approximate to 75%) and b= 100> (approximate to 25%) loops were present. Insideoutside contrast experiments were performed under safe orientations to determine the nature of loops. The interstitial-to-vacancy loop ratio turned out close to unity for 1/2 111 loops in W, and for both 1/2 111 and 100 loops in W5Re. However, interstitial loops were dominant for 100 loops in W. Re seemed to restrict loop mobility, leading to a smaller average loop size and a higher number density in the W-Re alloy.
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  • Thermally induced interface changes in W/B<sub>4</sub>C multilayers

    P.N. Rao   S.K. Rai   A.K. Sinha   M.N. Singh   G.S. Lodha  

    Abstract Multilayer period thickness changes for various thickness ratios, Γ (ratio of W layer thickness to period thickness) as a function of annealing temperatures were studied by grazing incidence X-ray reflectivity (GIXRR), and grazing incidence X-ray diffraction (GIXRD). Both period thickness expansion and compression were observed depending upon Γ and annealing temperatures. Multilayer with the W layer thickness close to the B 4 C layer has undergone less period thickness changes. Successive appearance and disappearance of multilayer Bragg maxima in GIXRR were observed. Such behavior suggested that redistribution of atomic density within bilayer, the displacement of interface and the multilayer period thickness change as annealing proceeds. GIXRD measurements performed using synchrotron radiation suggested the formation of phases corresponding to tungsten boride and carbide. Highlights • We reported the influence of the layer thickness on thermal stability of W/B 4 C multilayers. • Depending on the layer thickness ratio, the period variation can be positive or negative. • Diffusion induced structural changes can be minimized by optimizing layers thickness ratio. • Tungsten carbide and boride phases observed at elevated temperatures.
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  • W boson inclusive decays to quarkonium and B(c)(()*()) meson at the LHC

    Qiao, Cong-Feng   Sun, Li-Ping   Yang, De-Shan   Zhu, Rui-Lin  

    In this paper, the production rates of quarkonia eta(c), J/psi, eta(b), Y and B(c)(()*()) c mesons through W(+) boson decay at the LHC are calculated, at the leading order in both the QCD coupling as and in v, the typical velocity of the heavy quark inside mesons. It shows that a sizable number of quarkonia and B(c)(()*()) c mesons from W(+) boson decay will be produced at the LHC. Comparison with the predictions by using quark fragmentation mechanism is also discussed. Results show that, for the charmonium production through W(+) decay, the difference between predictions by the fragmentation mechanism and complete leading order calculation is around 3%, and it is insensitive to the uncertainties of theoretical parameters; however, for the bottomonium and B(c)(()*()) productions, the difference cannot be ignored as the fragmentation mechanism is less applicable here due to the relatively large ratio m(b)/m(w).
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  • Sintered (Ti,W)C carbides

    J. Jung    S. Kang  

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  • Symmetry Analysis of Ordered Phases of the Lower Tungsten Carbide W(2)C

    Kurlov, A. S.   Rempel, S. V.   Gusev, A. I.  

    The channels of disorder-order phase transitions through which there can arise orthorhombic (space group Pbcn) beta'-W(2)C, rhombohedral (space group P (3) over bar m1) beta''-W(2)C, and trigonal (space group P (3) over bar m1) epsilon-W(2)C superstructures of the disordered lower hexagonal carbide beta-W(2)C have been determined. The distribution functions of carbon atoms in the superstructures under consideration have been calculated, and the physically admissible sequence of transformations associated with the ordering of the lower carbide beta-W(2)C that occur with a decrease in the temperature has been established.
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  • J. W. Goethe and C. G. Carus: On the Representation of Nature in Science and Art

    Allert, Beate  

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  • Warren C. W. Chan (Ed.): Bio-applications of nanoparticles

    Alexander Le Blanc  

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  • Warren C. W. Chan (Ed.): Bio-applications of nanoparticles

    Alexander Le Blanc  

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  • Microstructure of (W,Ti)C–Co system containing platelet WC

    Hyomoon Nam   Jaehyuk Lim   Shinhoo Kang  

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