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Gheribi A.E.,Center for Research in Computational Thermochemistry | Lee J.J.,Defence Research and Development Canada | Thibault P.,TimeScales Scientific Ltd.
Materials Chemistry and Physics | Year: 2015

The present paper describes a theoretical method of examining thermodynamic equilibrium detonation states for reactions producing little or no gaseous products. Calculation of Phase Diagram (CALPHAD) techniques are used to calculate the thermodynamic states of the condensed-phase reaction at ambient conditions, and an analytical shock physics approach is used to estimate the detonation state. This method provides more accurate thermo-chemical equilibrium calculations for low-gas reactive mixtures, and can help evaluate the ability of a mixture to support a gasless detonation. A representative analysis was performed on an iron-aluminum thermite mixture and significant differences were found compared to previously published results. © 2014 Elsevier B.V. All rights reserved.


Gheribi A.E.,Center for Research in Computational Thermochemistry | Audet C.,Cole Polytechnique Campus Of University Of Montral | Le Digabel S.,Cole Polytechnique Campus Of University Of Montral | Blisle E.,Center for Research in Computational Thermochemistry | And 2 more authors.
Calphad: Computer Coupling of Phase Diagrams and Thermochemistry | Year: 2012

During alloy and process design, it is often desired to identify regions of design or process variables for which certain calculated functions have optimal values under various constraints, for example, compositions of minimum liquidus temperature in an N-component alloy; compositions where the amount of precipitate in a given phase is maximized or minimized during annealing or rolling; other calculated functions such as densities, vapor pressures and viscosities; or the overall cost. The present work reports on the development of software, linked to the FactSage thermodynamic and property database system, to perform such calculations. The software uses the Mesh Adaptive Direct Search algorithm (MADS) designed to solve non-smooth optimization problems for which the objectives and constraints are typically outputs of computer simulations. Numerical results for several examples are presented. © 2011 Elsevier Ltd. All rights reserved.


Lin C.,Shanghai University of Engineering Science | Wang S.,Shanghai University of Engineering Science | Chen G.,Shanghai University of Engineering Science | Wang K.,Center for Research in Computational Thermochemistry | And 5 more authors.
Ceramics International | Year: 2016

Based upon the experimental data available in the literature and present measurements, thermodynamic reassessments were initially performed on the binary BaO-ZrO2, BaO-YO1.5 systems, and the resultant thermodynamic parameters were then merged in combination with that of the previous ZrO2-YO1.5 system to derive a self-consistent thermodynamic description for the ZrO2-BaO-YO1.5 ternary system with limited ternary thermodynamic parameters. The Gibbs energies of all the liquid and terminal solid solution phases were treated by the substitutional solution model, the BZ phase featured by second solid solution described by the compound energy formalism (CEF) model, and the stoichiometric compound BZY424 and Ba2YZrO6-d modeled following the Neumann-Kopp rule. The calculated results agree well with the isothermal sections at 1600°C and 1750°C (1873K and 1923K) from both of the previous and present measured phase diagrams. This demonstrates that the thermodynamic parameters derived in the present work could be applicable to compositional optimizations of novel refractories for melting titanium alloys on the basis of this ternary oxide system. © 2016 Elsevier Ltd and Techna Group S.r.l.


Jin L.,Center for Research in Computational Thermochemistry | Kang Y.-B.,Center for Research in Computational Thermochemistry | Chartrand P.,Center for Research in Computational Thermochemistry | Fuerst C.D.,General Motors
Calphad: Computer Coupling of Phase Diagrams and Thermochemistry | Year: 2010

The AlGd, AlTb, AlDy, AlHo and AlEr (Alheavy rare earths) binary systems have been systematically assessed and optimized based on the available experimental data and ab-initio data using the FactSage thermodynamic software. A systematic technique (reduced melting temperature proposed by Gschneidner) was used for estimating the AlTb phase diagram due to lack of experimental data. Optimized model parameters of the Gibbs energies for all phases which reproduced all the reliable experimental data to satisfaction have been obtained. The optimization procedure was biased by putting a strong emphasis on the observed trends in the thermodynamic properties of AlRE phases. The Modified Quasichemical Model, which takes short-range ordering into account, is used for the liquid phase and the Compound Energy Formalism is used for the solid solutions in the binary systems. It is shown that the Modified Quasichemical Model used for the liquid alloys permits one to obtain entropies of mixing that are more reliable than that based on the BraggWilliams random mixing model which does not take short-range ordering into account. © 2010 Elsevier Ltd. All rights reserved.


Gheribi A.E.,Center for Research in Computational Thermochemistry | Gardarein J.-L.,Aix - Marseille University | Rigollet F.,Aix - Marseille University | Chartrand P.,Center for Research in Computational Thermochemistry
APL Materials | Year: 2014

In this paper, using both experimental data and theoretical modelling, we investigate the degradation of the thermal conductivity of sintered metals due simultaneously to the grain boundary thermal resistance and the porosity. We show that the porosity dependence of the thermal conductivity of sintered material from spherical particle powder, exhibits a critical behaviour associated with a second order phase transition. An analytical model with a single parameter is proposed to describe the critical behaviour of the thermal conductivity of sintered metals versus porosity. © 2014 Author(s).

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