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A complete thermodynamic description of the Ca–Ga system is needed to understand the thermodynamic behavior of GaN single crystal growth by the flux method. Using the CALPHAD technique, the phase equilibria and thermodynamic properties of the binary Ca–Ga system were explored with existing experimental data on phase boundaries and thermochemical measurements in the solid phases. The nine intermetallic...
The size-dependent melting temperature of metallic nanoparticles (NPs) is generally examined on a solid substrate. However, most experimental works performed on a solid substrate were explained by a homogeneous particle model without considering the effect of the substrate. For example, in the previous studies, the melting temperatures of gold NPs were examined on carbon or tungsten substrates. However,...
Thermodynamic modeling and optimization of the Gd–Mg, Mg–Y, Gd–Y binary systems and the Gd–Mg–Y ternary system have been critically carried out by means of the CALPHAD (CALculation of PHAse Diagrams) technique. The solution phases (liquid, body-centered cubic, and hexagonal close-packed) are modeled with the Redlich–Kister equation. The Compound Energy Model has been used to describe the thermodynamic...
The Ag–Au–Bi system has been thermodynamically assessed through the Calphad approach by combining recently derived experimental data, in particular the phase diagram equilibria and the integral enthalpies of mixing of its liquid phase. A good agreement is obtained between the calculation and the experimental data. The resulting assessment will be incorporated into the thermodynamic description of...
Surface tensions of the Sn–Ga–In ternary alloy are calculated from the surface tensions of the Sn–Ga, Ga–In and In–Sn sub-binary systems by using geometric models (the Kohler model and the Toop model), and a general solution model (the Chou model). The calculated results are in excellent agreement with the experimental data (except for the Kohler model), assuming an experimental accuracy of ±2.5%...
The thermodynamic modelling of solid (crystalline) phases forms a central topic within the Calphad approach and a variety of aspects have been discussed at previous Ringberg workshops. At the present Ringberg workshop, modelling of volume and its temperature, pressure and composition dependence formed a major part of the discussions. In addition, modelling of the heat capacity above the (equilibrium)...
A semi-empirical interatomic potential for silicon has been developed, based on the modified embedded atom method formalism. This potential describes elastic, structural, point defect, surface, thermal (except melting point), and cluster properties as satisfactorily as any other empirical potential ever developed. When compared to the previously developed MEAM Si potential [M.I. Baskes, J.S. Nelson,...
Pure iron samples were carburised at 500 ∘ C in CO–H 2 –H 2 O–H 2 S gas mixtures to study the growth kinetics of metastable iron carbides. The carbon activity was varied in the range 7≤aC≤4580. Small amounts of H 2 S were added to the atmosphere to prevent graphite deposition and metal dusting from occurring. The gas composition was optimised to obtain parabolic...
The Zn–Fe–Al system was assessed by using the CALPHAD technique. The optimization was based on three cornerstones. Firstly, crystallographically consistent sublattice models recently proposed by Nakano et al. for all intermetallic phases in the Zn–Fe system made it possible to predict which sublattice(s) would be most capable of hosting aluminum. Secondly, a careful analysis of all available phase...
Complex equilibria and phase transformations involving diffusion can now be calculated quickly and efficiently. Detailed examples are given for cases which involve varying degrees of non-equilibrium and therefore time-dependence. Despite very good agreement between such calculations and experimental results, many potential end-users are still not convinced that such techniques could be usefully applied...
The purpose of this article is to give a set of recommendations to producers of assessed thermodynamic data, who may be involved in either the critical evaluation of limited chemical systems or the creation and dissemination of larger thermodynamic databases. Also, it is hoped that reviewers and editors of scientific publications in this field will find some of the information useful. Good practice...
The increased application of quantum-mechanical-based methodologies to the study of alloy stability has required a re-assessment of the field. The focus is mainly on inorganic materials in the solid state. In a first part, after a brief overview of the so-called ab initio methods with their approximations, constraints, and limitations, recommendations are made for a good usage of first-principles...
Quasiperiodic phases (quasicrystals) have been found in numerous alloy systems of aluminum with transition metals (TM) between about 60 and 85 at.% Al. In binary Al–TM systems only metastable quasicrystals were observed, while in several ternary systems containing Cu, Ni or Pd the quasicrystals are stable. Many stable and metastable periodic phases formed in these compositional ranges exhibit structural...
The Cu–Eu and Cu–Yb binary systems have been assessed with CALPHAD method. Liquid, BCC and FCC phases are treated as substitutional solution phases, of which the excess Gibbs energies are modeled by Redlich–Kister polynomial functions. The binary intermetallic compounds are treated as stoichiometric phases. Thermodynamic parameters of various phases have been optimized and the calculated results are...
The technically important quasi-ternary section Si 3 N 4 –AlN–Al 2 O 3 –SiO 2 of the Si–Al–O–N system has been thermodynamically reassessed. Improved descriptions for the Gibbs energies of the β- and O′-sialon phases are applied. Different modelings according to the different behaviors of the reciprocal system within the β-sialon phase are discussed. The liquid...
The molar volumes of the fcc, bcc, hcp and liquid phases of Al, Li, Mg and Si as well as diamond Si have been evaluated as functions of temperature based on experimental data from the literature. The molar volume of each element in each structure is described by a single polynomial expression as a function of temperature. These polynomials can be used above around 150 K. The molar volumes of the liquids...
The phase diagram of the Dy–Ga binary system was reinvestigated by differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis. The existence of the compounds Dy 5 Ga 3 , DyGa, DyGa 2 , DyGa 3 and DyGa 6 was confirmed at low temperature in this system. A new high temperature intermetallic compound may exist between DyGa and DyGa 2 at...
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