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Akihisa Inoue - One of the best experts on this subject based on the ideXlab platform.

  • volume and viscosity of zr cu al glass forming Liquid Alloys
    Journal of Non-crystalline Solids, 2009
    Co-Authors: Yoshihiko Yokoyama, Takehiko Ishikawa, Junpei T Okada, Yasuhiro Watanabe, S Nanao, Akihisa Inoue
    Abstract:

    Abstract We examined the volume and viscosity of Zr–Cu–Al glass-forming Liquid Alloys to clarify the origin of a frozen free volume in glassy Alloys. Since an excess free volume imparts toughness and ductility to glassy Alloys, we attempted to increase this volume in glass structures so that they could be used as engineering materials. The maximum frozen excess free volume was observed in the ternary eutectic composition of the Zr–Cu–Al alloy system; however, its origin remains unclear. We attempted to reveal the mechanism of the formation of the frozen excess free volume in Zr–Cu–Al glassy Alloys.

  • viscosity measurements of zr55cu30al10ni5 and zr50cu40 xal10pdx x 0 3 and 7 at supercooled Liquid Alloys by using a penetration viscometer
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2007
    Co-Authors: S Maeda, T Yamasaki, Yoshihiko Yokoyama, Daisuke Okai, Takeshi Fukami, Hisamichi Kimura, Akihisa Inoue
    Abstract:

    Abstract Viscosity of Zr 55 Cu 30 Al 10 Ni 5 and Zr 50 Cu 40− x Al 10 Pd x ( x  = 0, 3 and 7 at.%) supercooled Liquid Alloys having bulk metallic glass forming ability has been measured by using a penetration viscometer with a cylindrical probe under high speed heating conditions at heating rates between 20 and 400 K/min in the temperature range from the glass transition temperatures ( T g ) up to above the crystallization temperatures. Effect of Pd addition on the viscosity of Zr-base supercooled Liquid Alloys has been also examined. The viscosity of these Alloys decreased with increasing the heating rate and tended to saturate at the heating rate of 200 K/min and above. These viscosities can be well represented by the Arrhenius relation. The activation energy for viscous flow for Zr 55 Cu 30 Al 10 Ni 5 supercooled Liquid Alloys was about 350 kJ/mol. In the Zr 50 Cu 40− x Al 10 Pd x ( x  = 0, 3 and 7 at.%) Alloys, the viscosities increased with increasing the Pd-content, while the activation energy for viscous flow decreased from 337 to 276 kJ/mol.

  • viscosity measurements of zr55cu30al10ni5 supercooled Liquid Alloys by using penetration viscometer under high speed heating conditions
    Intermetallics, 2006
    Co-Authors: T Yamasaki, S Maeda, Yoshihiko Yokoyama, Daisuke Okai, Takeshi Fukami, Hisamichi Kimura, Akihisa Inoue
    Abstract:

    Abstract The viscosity of Zr55Cu30Al10Ni5 supercooled Liquid Alloys having bulk metallic glass forming ability was measured using a penetration viscometer with a cylindrical probe under at heating rates as high as 400 °C/min. Viscosity decreased with an increase in the heating rate and tended to saturate at 200 °C/min and above. This may partly indicate a decrease in the oxygen contamination from the measuring atmosphere and partly due to differences in structural relaxation during heating at various rates. The viscosity of these Alloys can be well represented by an Arrhenius relation. The activation energies for viscous flow with various heating rates were all at values of about 340–350 kJ/mol. Viscosity follows a Vogel–Fulcher–Tammann (VFT) relationship over the entire temperature range.

  • viscosity measurements of zr55cu30al10ni5 and pd40cu30ni10p20 supercooled Liquid Alloys by using a penetration viscometer
    Materials Transactions, 2005
    Co-Authors: T Yamasaki, S Maeda, Yoshihiko Yokoyama, Daisuke Okai, Takeshi Fukami, Hisamichi Kimura, Akihisa Inoue
    Abstract:

    Viscosity of Zr 55 Cu 30 Al 10 Ni 5 and Pd 40 Cu 30 Ni 10 P 20 supercooled Liquid Alloys having bulk metallic glass forming ability has been measured by using a penetration viscometer with a cylindrical probe under high speed heating conditions at heating rates between 20 and 400°C/ min in the temperature range from the glass transition temperatures (Tg) up to above the crystallization temperatures. The viscosity of these Alloys decreased with increasing the heating rate and tended to saturate at the heating rate of 200°C/min and above. Their viscosity could be well represented by the Arrhenius relation. The activation energies for viscous flow for Zr 55 Cu 30 Al 10 Ni 5 and Pd 40 Cu 30 Ni 10 P 20 supercooled Liquid Alloys were about 350 and 250kJ/mol, respectively. The viscosity was also fitted by a Vogel-Fulcher-Tammann (VFT) relationship over the entire temperature range.

Ferdinand Sommer - One of the best experts on this subject based on the ideXlab platform.

  • Viscosity of Liquid Alloys: generalization of Andrade's equation
    Monatshefte Fur Chemie, 2012
    Co-Authors: Ram Nadan Singh, Ferdinand Sommer
    Abstract:

    The Andrade relation for the viscosity of Liquid metals has been reformulated in terms of the Debye temperature for Liquid metals. This semi-empirical relation has been extended to obtain a relation to calculate the composition and temperature dependence of the viscosity of Liquid Alloys using parameters which can be determined experimentally. The important inputs are the enthalpy of formation, ΔH, and the excess volume of mixing, ΔΩ. The composition dependence of the viscosity and its deviation from linear behavior could be positive or negative depending on the sign and magnitude of ΔH and ΔΩ. Several limiting cases of the semi-empirical relation for the viscosity of Liquid Alloys are compared and discussed. The results of the semi-empirical relation for viscosity isotherms for binary and ternary Liquid Alloys are mostly in reasonable agreement with available experimental results.

  • Thermodynamics of Liquid Alloys
    Journal of Non-crystalline Solids, 2007
    Co-Authors: Ferdinand Sommer
    Abstract:

    The experimental methods (calorimetric measurements, measurements of vapor pressure and electromotive forces) to obtain reliable thermodynamic data of Liquid Alloys at constant pressure as a function of composition and temperature are briefly reviewed. The main objective of the experimental work is the direct and most accurate determination of the partial or integral values of the enthalpy and Gibbs energy of formation as well as the measurement of the heat capacity. A consistent set of macroscopic thermodynamic data is important, e.g. to test the potential of a thermodynamic model of Liquid Alloys to describe quantitatively the experimentally determined composition and temperature dependencies, to test the extrapolation of thermodynamic properties into regions of temperature and composition where direct experimental measurements do not exist and to examine the microscopic assumptions of a thermodynamic model. A semi-empirical approach to calculate thermodynamic properties of Liquid Alloys could be used if experimental data are not accessible.

  • Thermodynamic investigation of viscosity in Cu–Bi and Bi–Zn Liquid Alloys
    Journal of Alloys and Compounds, 1998
    Co-Authors: O. Akinlade, Ram Nandan Singh, Ferdinand Sommer
    Abstract:

    Abstract We use a recently proposed formalism that relates thermodynamic properties and viscosity to investigate the role of energetics and size effects on Cu–Bi and Bi–Zn Liquid Alloys. Our calculations indicate that the model works quite well for Cu–Bi, while the results for Bi–Zn are not of similar quality. Furthermore, we show that size effects are more significant for Bi–Zn Liquid Alloys.

  • Thermodynamics of Liquid Alloys
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 1997
    Co-Authors: Ferdinand Sommer
    Abstract:

    Abstract An adiabatic calorimeter was used to measure the dependence on temperature and composition of the heat capacity C p l (x, T) of Liquid magnesium-rich La-Mg-Ni, lanthanum-rich Al-La-Ni Alloys and of Al 7.5 Cu 17.5 Ni 10 Zr 65 . The C p l (x, T) of these Alloys exhibit large values near to the Liquidus temperature. C p l (x, T) values of the glass-forming Alloys exceed their values of the undercooled Liquid state above the glass transition temperature. The C p l dependence on temperature reveals therefore a maximum in the undercooled Liquid state. This specific behaviour of Liquid Alloys is described using an association model.

  • Non Arrhenius behaviour in demixing Liquid Alloys
    Physics and Chemistry of Liquids, 1995
    Co-Authors: R. N. Singh, Ferdinand Sommer
    Abstract:

    Abstract A simple thermodynamic approach is considered to investigate the temperature dependence of the chemical diffusion coefficient in binary Liquid Alloys exhibiting miscibility gaps. Application is made to Bi-Zn, Cd-Ga and Al-In which show non Arrhenius behaviour which is significantly marked in the critical region.

Alain Pasturel - One of the best experts on this subject based on the ideXlab platform.

  • Transport properties and Stokes-Einstein relation in Al-rich Liquid Alloys
    Journal of Chemical Physics, 2016
    Co-Authors: N. Jakse, Alain Pasturel
    Abstract:

    We use ab initio molecular dynamics simulations to study the transport properties and the validity of the Stokes-Einstein relation in Al-rich Liquid Alloys with Ni, Cu, and Zn as alloying elements. First, we show that the composition and temperature dependence of their transport properties present different behaviors, which can be related to their local structural ordering. Then, we evidence that the competition between the local icosahedral ordering and the local chemical ordering may cause the breakdown of the Stokes-Einstein relation even in the Liquid phase. We demonstrate that this breakdown can be captured by entropy-scaling relationships developed by Rosenfeld and using the two-body excess entropy. Our findings provide a unique framework to study the relation between structure, thermodynamics, and dynamics in metallic melts and pave the way towards the explanation of various complex transport properties in metallic melts. Published by AIP Publishing.

  • Bonding Mechanisms and Interatomic Forces in Ni-Al Liquid Alloys
    NATO ASI Series, 1994
    Co-Authors: Alain Pasturel
    Abstract:

    In the past decade, it has been a goal to combine at a high level of accuracy both quantum-mechanical and statistical-thermodynamical contributions to obtain a theoretical knowledge of the phase diagrams. One of the most efficient statistical-mechanics techniques in the Cluster-Variational method (CVM), which provides a good description of the free energy as a function of the short-range order 1. Based on a cluster expansion of the configurational free energy, it has been essentially used to deal with solid solutions or ordered phases presenting an extended concentration range. However Liquid Alloys may also display chemical short range order (CSRO) as has been shown recently for a series of metallic Alloys 2 and it appears as essential to consider this when determining their thermodynamic quantities.

O. Akinlade - One of the best experts on this subject based on the ideXlab platform.

  • Temperature dependence of thermodynamic properties of Si–Ti binary Liquid Alloys
    Thermochimica Acta, 2011
    Co-Authors: Y.a. Odusote, L.a. Hussain, O. Akinlade
    Abstract:

    Abstract This study is an attempt to extract useful thermodynamic information from experimental free energy of mixing of Si–Ti binary Liquid alloy at different temperatures. A number of temperature dependent thermodynamic functions are calculated in the frame of a simple approach based on a statistical mechanical model. It is reported that the thermodynamic functions of Si–Ti alloy exhibit strong negative deviation from Raoult’s law across the whole concentration range and the impact of temperatures on the Liquid alloy is explained. The energetics of mixing in the alloy has been explained through the study of activity, free energy of mixing, concentration fluctuations in the long-wavelength limits, chemical short-range order and diffusion. In addition, it is also observed that the tendency for intermetallic associations, which leads to the formation of SiTi compounds, decreases with the increase in temperature. This study reinforces further that useful thermodynamic information may be obtained from experimental data obtain using FactSage Thermo-Chemical Software and databases for binary Liquid Alloys.

  • A QUASI-LATTICE THEORY FOR COMPOUND FORMING TERNARY Liquid Alloys
    International Journal of Modern Physics B, 2006
    Co-Authors: O. Akinlade, L.a. Hussain
    Abstract:

    A Quasi-lattice model of Liquid binary mixtures has been used to establish a model for calculating some thermodynamic properties of compound forming ternary Liquid Alloys. The effect of varying Z on the concentration fluctuations was also investigated. Results obtained for limiting case of the model are presented and compared with that obtained by Bhatia and Singh for binary Liquid Alloys. A framework for calculating the Warren Cowley short range order for ternary Liquid Alloys as a function of Z is also formulated.

  • Demixing tendencies in some Sn-based Liquid Alloys
    Journal of Alloys and Compounds, 1999
    Co-Authors: O. Akinlade, A. O. Boyo, B.r. Ijaduola
    Abstract:

    Abstract We study the demixing tendencies observed in some Sn-based Liquid Alloys, specifically, Ga–Sn, Al–Sn and Fe–Sn Liquid Alloys using a phenomenological model. With the aid of the model, we investigate the concentration dependence of thermodynamic properties viz: activity, free energy of mixing, enthalpy of mixing, entropy of mixing and the chemical diffusion. The parameters that characterize the model, enable us to describe the energetics of the system in terms of the concentration–concentration fluctuations in the long wavelength limit. We deduce from our study that of the three Liquid Alloys, the thermodynamic properties of Fe–Sn are most asymmetric as a function of concentration, the observed asymmetry is explained on the basis of the size effect. From the results for Ga–Sn and Al–Sn, we infer that with increase in the atomic number of the element in group III that is added to Liquid Sn, there is a reduced tendency for segregation. We deduce within the present framework that In–Sn would be a hetero-coordinated system. This deduction is in agreement with available experimental data.

  • Thermodynamic investigation of viscosity in Cu–Bi and Bi–Zn Liquid Alloys
    Journal of Alloys and Compounds, 1998
    Co-Authors: O. Akinlade, Ram Nandan Singh, Ferdinand Sommer
    Abstract:

    Abstract We use a recently proposed formalism that relates thermodynamic properties and viscosity to investigate the role of energetics and size effects on Cu–Bi and Bi–Zn Liquid Alloys. Our calculations indicate that the model works quite well for Cu–Bi, while the results for Bi–Zn are not of similar quality. Furthermore, we show that size effects are more significant for Bi–Zn Liquid Alloys.

Klas Hjort - One of the best experts on this subject based on the ideXlab platform.

  • tape transfer atomization patterning of Liquid Alloys for microfluidic stretchable wireless power transfer
    Scientific Reports, 2015
    Co-Authors: Seung Hee Jeong, Klas Hjort
    Abstract:

    Stretchable electronics offers unsurpassed mechanical compliance on complex or soft surfaces like the human skin and organs. To fully exploit this great advantage, an autonomous system with a self-powered energy source has been sought for. Here, we present a new technology to pattern Liquid Alloys on soft substrates, targeting at fabrication of a hybrid-integrated power source in microfluidic stretchable electronics. By atomized spraying of a Liquid alloy onto a soft surface with a tape transferred adhesive mask, a universal fabrication process is provided for high quality patterns of Liquid conductors in a meter scale. With the developed multilayer fabrication technique, a microfluidic stretchable wireless power transfer device with an integrated LED was demonstrated, which could survive cycling between 0% and 25% strain over 1,000 times.