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Al System

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Nachum Frage – 1st expert on this subject based on the ideXlab platform

  • InterfaciAl Interaction and Wetting in the Ta_2O_5/Cu-Al System
    Journal of Materials Engineering and Performance, 2014
    Co-Authors: Orel Kish, Natalya Froumin, Michael Aizenshtein, Nachum Frage

    Abstract:

    Wettability and interfaciAl interaction of the Ta_2O_5/Cu-Al System were studied. Pure Cu does not wet the Ta_2O_5 substrate, and improved spreading is achieved when relatively a high fraction of the active element (~40 at.% Al) was added. The Al_2O_3 and AlTaO_4 phases were observed at the Ta_2O_5/Cu-Al interface. A thermodynamic evAluation Allowed us to suggest that the lack of wetting bellow 40 at.% Al is due to the presence of a native oxide, which covers the drop. The conditions of the native oxide decomposition and the formation of the volatile Al_2O suboxide strongly depend on the vacuum level during sessile drop experiments and the composition of the Cu-Al Alloy. In our case, Al contents greater than 40% provides thermodynamic conditions for the formation of Al_2O (as a result of Al reaction with Al_2O_3) and the drop spreading. It was suggested that the finAl contact angle in the Ta_2O_5/Cu-Al System (50°) is determined by Ta adsorption on the newly formed Alumina interlayer.

  • InterfaciAl Interaction and Wetting in the Ta2O5/Cu-Al System
    Journal of Materials Engineering and Performance, 2014
    Co-Authors: Orel Kish, Natalya Froumin, Michael Aizenshtein, Nachum Frage

    Abstract:

    Wettability and interfaciAl interaction of the Ta2O5/Cu-Al System were studied. Pure Cu does not wet the Ta2O5 substrate, and improved spreading is achieved when relatively a high fraction of the active element (~40 at.% Al) was added. The Al2O3 and AlTaO4 phases were observed at the Ta2O5/Cu-Al interface. A thermodynamic evAluation Allowed us to suggest that the lack of wetting bellow 40 at.% Al is due to the presence of a native oxide, which covers the drop. The conditions of the native oxide decomposition and the formation of the volatile Al2O suboxide strongly depend on the vacuum level during sessile drop experiments and the composition of the Cu-Al Alloy. In our case, Al contents greater than 40% provides thermodynamic conditions for the formation of Al2O (as a result of Al reaction with Al2O3) and the drop spreading. It was suggested that the finAl contact angle in the Ta2O5/Cu-Al System (50°) is determined by Ta adsorption on the newly formed Alumina interlayer.

  • Wetting phenomena in the TiC/(Cu–Al) System
    Acta Materialia, 2000
    Co-Authors: N. Froumin, Nachum Frage, M. Polak, Moshe P. Dariel

    Abstract:

    The wetting behavior in the TiC/(Cu–Al) System was studied by the sessile drop method over the entire Cu–Al Alloy concentration range. The experimentAl results show that the wetting evolution in the TiC/Cu System is controlled by partiAl dissolution of the titanium carbide phase. The presence of oxygen on the TiC surface strongly inhibits the interaction between the ceramic and molten Cu, thus leading to non-wetting conditions. The improved wetting of the oxygen-free TiC substrate by Cu–Al Alloys is due to the enhanced transfer of titanium from the carbide phase into the melt, and results from its increased solubility in the Al-containing molten Alloy. The wetting of TiC substrates covered with an oxygen-containing layer by a molten Cu–Al Alloy is affected by the reduction of this layer and transfer of the released Ti into the molten metAl. Enhanced wetting may Also result from in situ deoxidization of the surface of the Cu–Al liquid drop and of the TiC substrate due to the evaporation of the Al2O sub-oxide at elevated temperature. A thermodynamic anAlysis of the Systems under consideration is in good agreement with the experimentAl observations.

Jatin Bhatt – 2nd expert on this subject based on the ideXlab platform

  • Thermodynamic modelling to optimize glass forming composition in multicomponent Zr-Cu-Co-Al System
    Materials Today: Proceedings, 2020
    Co-Authors: Yogesh Prabhu, S. Vincent, Jatin Bhatt

    Abstract:

    Abstract Zr-rich bulk metAllic glasses (BMGs) exhibits exceptionAl combination of properties viz., high strength, better fracture toughness, and low young’s modulus Along with excellent corrosion and wear resistance. Prediction of glass forming ability (GFA) for Zr-rich Systems in terms of Alloy compositions is vitAl for appropriate materiAl design. The present work attempts to predict good glass forming composition in Zr-Cu-Co-Al System by understanding the influence of thermodynamic parameter such as enthAlpy of chemicAl mixing (ΔHchem) and topologicAl factors such as mismatch entropy (ΔSσ/kB) and configurationAl entropy (ΔSconfig/R). The GFA parameter PHS, which is the product of ΔHchem and ΔSconfig/R is used to determine Zr-rich quaternary composition by weighing approach. Further, the correlation between PHS and criticAl diameter was established using reported data in Zr-Cu-Co-Al System.

  • optimization of bulk metAllic glass forming compositions in zr cu Al System by thermodynamic modeling
    Intermetallics, 2007
    Co-Authors: Jatin Bhatt, Wu Jiang, Xia Junhai, Wang Qing, Chuang Dong, B S Murty

    Abstract:

    Abstract Compositions with high glass forming ability have been identified in Zr–Cu–Al System with the help of a thermodynamic parameter, which takes into account the enthAlpy of chemicAl mixing (ΔHchem), the mismatch entropy normAlized by Boltzmann’s constant (Sσ/kB) and the configurationAl entropy (Sconfig/R). The best bulk metAllic glass forming composition is identified as the one at ΔHchem and Sσ/kB maxima in a specific range of Sconfig/R. A product of thermodynamic parameters ( Δ H chem × S σ / k B ) is found to have strong correlation with glass forming ability and can help to identify the exact composition that can form bulk metAllic glass.

Y Mishin – 3rd expert on this subject based on the ideXlab platform

  • development of an interatomic potentiAl for the ni Al System
    Philosophical Magazine, 2009
    Co-Authors: Y Mishin

    Abstract:

    We construct an interatomic potentiAl for the Ni-Al System within the embedded-atom method formAlism. The potentiAl is based on previously developed accurate potentiAls for pure Ni and Al. The cross-interactions are fitted to experimentAl cohesive energy, lattice parameter and elastic constants of B2-NiAl, as well as to ab initio formation energies of severAl reAl or imaginary intermetAllic compounds with different crystAl structures and chemicAl compositions. The potentiAl accurately reproduces a variety of physicAl properties of the NiAl and Ni3Al phases, and shows reasonable agreement with experimentAl and ab initio data for phase stability across the Ni-Al phase diagram. Most of the properties reproduced by the new potentiAl were not involved in the fitting process, which demonstrates its excellent transferability. Advantages and certain weaknesses of the new potentiAl in comparison with other existing potentiAls are discussed in detail. The potentiAl is expected to be especiAlly suitable for simulati…

  • interatomic potentiAls for atomistic simulations of the ti Al System
    Physical Review B, 2003
    Co-Authors: Rajendra R Zope, Y Mishin

    Abstract:

    SemiempiricAl interatomic potentiAls have been developed for Al, $\ensuremath{\Alpha}\ensuremath{-}\mathrm{Ti},$ and $\ensuremath{\gamma}\ensuremath{-}\mathrm{TiAl}$ within the embedded atom method (EAM) formAlism by fitting to a large database of experimentAl as well as ab initio data. The ab initio cAlculations were performed by the linearized augmented plane wave (LAPW) method within the density functionAl theory to obtain the equations of state for a number of crystAl structures of the Ti-Al System. Some of the cAlculated LAPW energies were used for fitting the potentiAls while others for examining their quAlity. The potentiAls correctly predict the equilibrium crystAl structures of the phases and accurately reproduce their basic lattice properties. The potentiAls are applied to cAlculate the energies of point defects, surfaces, and planar faults in the equilibrium structures. Unlike earlier EAM potentiAls for the Ti-Al System, the proposed potentiAls provide a reasonable description of the lattice thermAl expansion, demonstrating their usefulness for molecular-dynamics and Monte Carlo simulations at high temperatures. The energy Along the tetragonAl deformation path (Bain transformation) in $\ensuremath{\gamma}\ensuremath{-}\mathrm{TiAl}$ cAlculated with the EAM potentiAl is in fairly good agreement with LAPW cAlculations. Equilibrium point defect concentrations in $\ensuremath{\gamma}\ensuremath{-}\mathrm{TiAl}$ are studied using the EAM potentiAl. It is found that antisite defects strongly dominate over vacancies at All compositions around stoichiometry, indicating that $\ensuremath{\gamma}\ensuremath{-}\mathrm{TiAl}$ is an antisite disorder compound, in agreement with experimentAl data.

  • diffusion in the ti Al System
    Acta Materialia, 2000
    Co-Authors: Y Mishin, Chr Herzig

    Abstract:

    Many properties of industriAl Ti–Al Alloys, such as high-temperature stability of the lamellar structure and creep resistance, are determined by diffusion rates in the phases and Along the interfaces. The knowledge of diffusion characteristics and fundamentAl understanding of diffusion mechanisms are of great importance to the research and design of industriAl Ti–Al Alloys. This paper gives an overview of recent progress in experimentAl and theoreticAl studies of diffusion behavior in the phases of the Ti–Al System. The experimentAl methods used in modern diffusion measurements are briefly described, and recent experimentAl results for Ti and Al diffusion in α-Ti(Al), β-Ti(Al), and intermetAllic phases α2-Ti3Al and γ-TiAl, are summarized. The results for interdiffusion and impurity diffusion in these phases are Also discussed in detail. The second part of the paper provides an overview of current understanding of point defects and diffusion mechanisms in Ti3Al and TiAl. A statisticAl model of point-defect disorder in ordered compounds is presented and applied to Ti3Al and TiAl using input data generated with embedded-atom potentiAls. Possible atomic mechanisms of diffusion in these compounds are anAlyzed in detail, and methods of diffusion cAlculations under different mechanisms are reviewed. The relative importance of different mechanisms in Ti3Al and TiAl is evAluated by comparing their estimated activation energies. Prospective topics of further experimentAl and theoreticAl research in this area are outlined.