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COMPUTER SCIENCE (1162 journals)                  1 2 3 4 5 6 | Last

Showing 1 - 200 of 872 Journals sorted alphabetically
3D Printing and Additive Manufacturing     Full-text available via subscription   (Followers: 13)
Abakós     Open Access   (Followers: 4)
ACM Computing Surveys     Hybrid Journal   (Followers: 23)
ACM Journal on Computing and Cultural Heritage     Hybrid Journal   (Followers: 9)
ACM Journal on Emerging Technologies in Computing Systems     Hybrid Journal   (Followers: 13)
ACM Transactions on Accessible Computing (TACCESS)     Hybrid Journal   (Followers: 3)
ACM Transactions on Algorithms (TALG)     Hybrid Journal   (Followers: 16)
ACM Transactions on Applied Perception (TAP)     Hybrid Journal   (Followers: 6)
ACM Transactions on Architecture and Code Optimization (TACO)     Hybrid Journal   (Followers: 9)
ACM Transactions on Autonomous and Adaptive Systems (TAAS)     Hybrid Journal   (Followers: 7)
ACM Transactions on Computation Theory (TOCT)     Hybrid Journal   (Followers: 12)
ACM Transactions on Computational Logic (TOCL)     Hybrid Journal   (Followers: 4)
ACM Transactions on Computer Systems (TOCS)     Hybrid Journal   (Followers: 18)
ACM Transactions on Computer-Human Interaction     Hybrid Journal   (Followers: 14)
ACM Transactions on Computing Education (TOCE)     Hybrid Journal   (Followers: 5)
ACM Transactions on Design Automation of Electronic Systems (TODAES)     Hybrid Journal   (Followers: 1)
ACM Transactions on Economics and Computation     Hybrid Journal  
ACM Transactions on Embedded Computing Systems (TECS)     Hybrid Journal   (Followers: 4)
ACM Transactions on Information Systems (TOIS)     Hybrid Journal   (Followers: 21)
ACM Transactions on Intelligent Systems and Technology (TIST)     Hybrid Journal   (Followers: 8)
ACM Transactions on Interactive Intelligent Systems (TiiS)     Hybrid Journal   (Followers: 3)
ACM Transactions on Multimedia Computing, Communications, and Applications (TOMCCAP)     Hybrid Journal   (Followers: 10)
ACM Transactions on Reconfigurable Technology and Systems (TRETS)     Hybrid Journal   (Followers: 7)
ACM Transactions on Sensor Networks (TOSN)     Hybrid Journal   (Followers: 9)
ACM Transactions on Speech and Language Processing (TSLP)     Hybrid Journal   (Followers: 11)
ACM Transactions on Storage     Hybrid Journal  
ACS Applied Materials & Interfaces     Full-text available via subscription   (Followers: 25)
Acta Automatica Sinica     Full-text available via subscription   (Followers: 3)
Acta Universitatis Cibiniensis. Technical Series     Open Access  
Ad Hoc Networks     Hybrid Journal   (Followers: 11)
Adaptive Behavior     Hybrid Journal   (Followers: 11)
Advanced Engineering Materials     Hybrid Journal   (Followers: 26)
Advanced Science Letters     Full-text available via subscription   (Followers: 9)
Advances in Adaptive Data Analysis     Hybrid Journal   (Followers: 8)
Advances in Artificial Intelligence     Open Access   (Followers: 16)
Advances in Calculus of Variations     Hybrid Journal   (Followers: 2)
Advances in Catalysis     Full-text available via subscription   (Followers: 5)
Advances in Computational Mathematics     Hybrid Journal   (Followers: 15)
Advances in Computer Science : an International Journal     Open Access   (Followers: 14)
Advances in Computing     Open Access   (Followers: 2)
Advances in Data Analysis and Classification     Hybrid Journal   (Followers: 51)
Advances in Engineering Software     Hybrid Journal   (Followers: 26)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 10)
Advances in Human Factors/Ergonomics     Full-text available via subscription   (Followers: 26)
Advances in Human-Computer Interaction     Open Access   (Followers: 20)
Advances in Materials Sciences     Open Access   (Followers: 16)
Advances in Operations Research     Open Access   (Followers: 11)
Advances in Parallel Computing     Full-text available via subscription   (Followers: 7)
Advances in Porous Media     Full-text available via subscription   (Followers: 4)
Advances in Remote Sensing     Open Access   (Followers: 39)
Advances in Science and Research (ASR)     Open Access   (Followers: 6)
Advances in Technology Innovation     Open Access   (Followers: 3)
AEU - International Journal of Electronics and Communications     Hybrid Journal   (Followers: 8)
African Journal of Information and Communication     Open Access   (Followers: 8)
African Journal of Mathematics and Computer Science Research     Open Access   (Followers: 4)
Air, Soil & Water Research     Open Access   (Followers: 9)
AIS Transactions on Human-Computer Interaction     Open Access   (Followers: 6)
Algebras and Representation Theory     Hybrid Journal   (Followers: 1)
Algorithms     Open Access   (Followers: 11)
American Journal of Computational and Applied Mathematics     Open Access   (Followers: 4)
American Journal of Computational Mathematics     Open Access   (Followers: 4)
American Journal of Information Systems     Open Access   (Followers: 5)
American Journal of Sensor Technology     Open Access   (Followers: 4)
Anais da Academia Brasileira de Ciências     Open Access   (Followers: 2)
Analog Integrated Circuits and Signal Processing     Hybrid Journal   (Followers: 7)
Analysis in Theory and Applications     Hybrid Journal   (Followers: 1)
Animation Practice, Process & Production     Hybrid Journal   (Followers: 5)
Annals of Combinatorics     Hybrid Journal   (Followers: 3)
Annals of Data Science     Hybrid Journal   (Followers: 11)
Annals of Mathematics and Artificial Intelligence     Hybrid Journal   (Followers: 7)
Annals of Pure and Applied Logic     Open Access   (Followers: 2)
Annals of Software Engineering     Hybrid Journal   (Followers: 13)
Annual Reviews in Control     Hybrid Journal   (Followers: 6)
Anuario Americanista Europeo     Open Access  
Applicable Algebra in Engineering, Communication and Computing     Hybrid Journal   (Followers: 2)
Applied and Computational Harmonic Analysis     Full-text available via subscription   (Followers: 1)
Applied Artificial Intelligence: An International Journal     Hybrid Journal   (Followers: 13)
Applied Categorical Structures     Hybrid Journal   (Followers: 2)
Applied Clinical Informatics     Hybrid Journal   (Followers: 2)
Applied Computational Intelligence and Soft Computing     Open Access   (Followers: 12)
Applied Computer Systems     Open Access   (Followers: 1)
Applied Informatics     Open Access  
Applied Mathematics and Computation     Hybrid Journal   (Followers: 33)
Applied Medical Informatics     Open Access   (Followers: 11)
Applied Numerical Mathematics     Hybrid Journal   (Followers: 5)
Applied Soft Computing     Hybrid Journal   (Followers: 16)
Applied Spatial Analysis and Policy     Hybrid Journal   (Followers: 4)
Architectural Theory Review     Hybrid Journal   (Followers: 3)
Archive of Applied Mechanics     Hybrid Journal   (Followers: 5)
Archive of Numerical Software     Open Access  
Archives and Museum Informatics     Hybrid Journal   (Followers: 134)
Archives of Computational Methods in Engineering     Hybrid Journal   (Followers: 4)
Artifact     Hybrid Journal   (Followers: 2)
Artificial Life     Hybrid Journal   (Followers: 7)
Asia Pacific Journal on Computational Engineering     Open Access  
Asia-Pacific Journal of Information Technology and Multimedia     Open Access   (Followers: 1)
Asian Journal of Computer Science and Information Technology     Open Access  
Asian Journal of Control     Hybrid Journal  
Assembly Automation     Hybrid Journal   (Followers: 2)
at - Automatisierungstechnik     Hybrid Journal   (Followers: 1)
Australian Educational Computing     Open Access   (Followers: 1)
Automatic Control and Computer Sciences     Hybrid Journal   (Followers: 4)
Automatic Documentation and Mathematical Linguistics     Hybrid Journal   (Followers: 5)
Automatica     Hybrid Journal   (Followers: 11)
Automation in Construction     Hybrid Journal   (Followers: 6)
Autonomous Mental Development, IEEE Transactions on     Hybrid Journal   (Followers: 8)
Basin Research     Hybrid Journal   (Followers: 5)
Behaviour & Information Technology     Hybrid Journal   (Followers: 52)
Biodiversity Information Science and Standards     Open Access  
Bioinformatics     Hybrid Journal   (Followers: 272)
Biomedical Engineering     Hybrid Journal   (Followers: 15)
Biomedical Engineering and Computational Biology     Open Access   (Followers: 14)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 17)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 33)
Briefings in Bioinformatics     Hybrid Journal   (Followers: 45)
British Journal of Educational Technology     Hybrid Journal   (Followers: 128)
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 10)
c't Magazin fuer Computertechnik     Full-text available via subscription   (Followers: 2)
CALCOLO     Hybrid Journal  
Calphad     Hybrid Journal  
Canadian Journal of Electrical and Computer Engineering     Full-text available via subscription   (Followers: 14)
Capturing Intelligence     Full-text available via subscription  
Catalysis in Industry     Hybrid Journal   (Followers: 1)
CEAS Space Journal     Hybrid Journal   (Followers: 1)
Cell Communication and Signaling     Open Access   (Followers: 1)
Central European Journal of Computer Science     Hybrid Journal   (Followers: 5)
CERN IdeaSquare Journal of Experimental Innovation     Open Access  
Chaos, Solitons & Fractals     Hybrid Journal   (Followers: 3)
Chemometrics and Intelligent Laboratory Systems     Hybrid Journal   (Followers: 14)
ChemSusChem     Hybrid Journal   (Followers: 7)
China Communications     Full-text available via subscription   (Followers: 7)
Chinese Journal of Catalysis     Full-text available via subscription   (Followers: 2)
CIN Computers Informatics Nursing     Full-text available via subscription   (Followers: 12)
Circuits and Systems     Open Access   (Followers: 16)
Clean Air Journal     Full-text available via subscription   (Followers: 2)
CLEI Electronic Journal     Open Access  
Clin-Alert     Hybrid Journal   (Followers: 1)
Cluster Computing     Hybrid Journal   (Followers: 1)
Cognitive Computation     Hybrid Journal   (Followers: 4)
COMBINATORICA     Hybrid Journal  
Combustion Theory and Modelling     Hybrid Journal   (Followers: 13)
Communication Methods and Measures     Hybrid Journal   (Followers: 12)
Communication Theory     Hybrid Journal   (Followers: 20)
Communications Engineer     Hybrid Journal   (Followers: 1)
Communications in Algebra     Hybrid Journal   (Followers: 3)
Communications in Partial Differential Equations     Hybrid Journal   (Followers: 3)
Communications of the ACM     Full-text available via subscription   (Followers: 54)
Communications of the Association for Information Systems     Open Access   (Followers: 18)
COMPEL: The International Journal for Computation and Mathematics in Electrical and Electronic Engineering     Hybrid Journal   (Followers: 3)
Complex & Intelligent Systems     Open Access  
Complex Adaptive Systems Modeling     Open Access  
Complex Analysis and Operator Theory     Hybrid Journal   (Followers: 2)
Complexity     Hybrid Journal   (Followers: 6)
Complexus     Full-text available via subscription  
Composite Materials Series     Full-text available via subscription   (Followers: 9)
Computación y Sistemas     Open Access  
Computation     Open Access  
Computational and Applied Mathematics     Hybrid Journal   (Followers: 2)
Computational and Mathematical Methods in Medicine     Open Access   (Followers: 2)
Computational and Mathematical Organization Theory     Hybrid Journal   (Followers: 2)
Computational and Structural Biotechnology Journal     Open Access   (Followers: 2)
Computational and Theoretical Chemistry     Hybrid Journal   (Followers: 9)
Computational Astrophysics and Cosmology     Open Access   (Followers: 1)
Computational Biology and Chemistry     Hybrid Journal   (Followers: 11)
Computational Chemistry     Open Access   (Followers: 2)
Computational Cognitive Science     Open Access   (Followers: 2)
Computational Complexity     Hybrid Journal   (Followers: 4)
Computational Condensed Matter     Open Access  
Computational Ecology and Software     Open Access   (Followers: 9)
Computational Economics     Hybrid Journal   (Followers: 9)
Computational Geosciences     Hybrid Journal   (Followers: 15)
Computational Linguistics     Open Access   (Followers: 23)
Computational Management Science     Hybrid Journal  
Computational Mathematics and Modeling     Hybrid Journal   (Followers: 8)
Computational Mechanics     Hybrid Journal   (Followers: 4)
Computational Methods and Function Theory     Hybrid Journal  
Computational Molecular Bioscience     Open Access   (Followers: 2)
Computational Optimization and Applications     Hybrid Journal   (Followers: 7)
Computational Particle Mechanics     Hybrid Journal   (Followers: 1)
Computational Research     Open Access   (Followers: 1)
Computational Science and Discovery     Full-text available via subscription   (Followers: 2)
Computational Science and Techniques     Open Access  
Computational Statistics     Hybrid Journal   (Followers: 13)
Computational Statistics & Data Analysis     Hybrid Journal   (Followers: 30)
Computer     Full-text available via subscription   (Followers: 87)
Computer Aided Surgery     Hybrid Journal   (Followers: 3)
Computer Applications in Engineering Education     Hybrid Journal   (Followers: 7)
Computer Communications     Hybrid Journal   (Followers: 10)
Computer Engineering and Applications Journal     Open Access   (Followers: 5)
Computer Journal     Hybrid Journal   (Followers: 8)
Computer Methods in Applied Mechanics and Engineering     Hybrid Journal   (Followers: 21)
Computer Methods in Biomechanics and Biomedical Engineering     Hybrid Journal   (Followers: 10)
Computer Methods in the Geosciences     Full-text available via subscription   (Followers: 1)
Computer Music Journal     Hybrid Journal   (Followers: 16)
Computer Physics Communications     Hybrid Journal   (Followers: 6)
Computer Science - Research and Development     Hybrid Journal   (Followers: 7)
Computer Science and Engineering     Open Access   (Followers: 17)
Computer Science and Information Technology     Open Access   (Followers: 12)
Computer Science Education     Hybrid Journal   (Followers: 13)
Computer Science Journal     Open Access   (Followers: 20)

        1 2 3 4 5 6 | Last

Journal Cover Calphad
  [SJR: 1.116]   [H-I: 44]   [0 followers]  Follow
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 0364-5916
   Published by Elsevier Homepage  [3089 journals]
  • Thermodynamic assessment of binary erythritol-xylitol phase diagram for
           phase change materials design
    • Abstract: Publication date: March 2018
      Source:Calphad, Volume 60
      Author(s): Saman Nimali Gunasekara, Huahai Mao, Sedigheh Bigdeli, Justin NingWei Chiu, Viktoria Martin
      Here, the erythritol-xylitol binary system was thermodynamically optimized based on available experimental phase equilibrium data, to explore compositions suitable as phase change materials (PCMs) for thermal energy storage (TES). A previous experimental study revealed that erythritol-xylitol was a partially isomorphous system with a eutectic. In the thermodynamic evaluation, the CALPHAD method was employed coupling the phase diagram and thermodynamic property information. There, both unary and binary systems’ experimental data were taken into account, and all phases were described using the substitutional solution model. Finally, a self-consistent thermodynamic description for the erythritol-xylitol system was achieved. The calculated eutectic point is at 76.7°C and 26.8mol% erythritol, agreeing well with the experimental data. The calculated phase diagram better-verifies the systems’ solidus and the solvus, disclosing the stable phase relations. Based on the Gibbs energy minimization, phase diagrams can be predicted for the binary and higher order systems, provided the component subsystems are thermodynamically assessed beforehand. In conclusion, to move forward beyond e.g. non-isomorphous simple eutectic systems, methods using Gibbs free energy minimization from a fundamental point-of-view such as CALPHAD are essential.

      PubDate: 2017-12-13T09:33:36Z
  • Thermodynamics of liquid Sn-Pb alloys determined by vapour pressure
    • Abstract: Publication date: March 2018
      Source:Calphad, Volume 60
      Author(s): Andrzej Zajączkowski
      Application of Knudsen method in the studies of liquid Sn-Pb alloys, containing from 4.85 to 95.31mol% of lead, in temperatures from 851 to 1186K, and liquid tin and lead, in temperatures 1360 – 1442 and 934 – 1149K, respectively, provided experimental data which made characterization of thermodynamic properties of liquid phase of Sn-Pb system possible. Parameters of the Redlich-Kister equation, describing excess Gibbs energy of liquid phase of the examined system, were determined. With application of the third law method standard enthalpies of sublimation of tin and lead were calculated.

      PubDate: 2017-12-13T09:33:36Z
  • Assessment of the Al-Bi-Mg system and extrapolation to the Al-Bi-Mg-Sn
           quaternary system
    • Abstract: Publication date: March 2018
      Source:Calphad, Volume 60
      Author(s): Chunju Niu, Changrong Li
      The phase equilibria in the Al-Bi-Mg-Sn quaternary system have been studied using the CALPHAD (CALculation of PHAse Diagram) method. One of the four ternary systems constituting the quarternary system, the Al-Bi-Mg system, is re-assessed by means of the CALPHAD technique and Thermo-Calc software package, in consideration of the associate model for the liquid phase instead of the Modified Quasi-chemical Model used in the literature report. While for the other three ternary systems, the Al-Bi-Sn, the Al-Mg-Sn and the Bi-Mg-Sn systems, the thermodynamic parameters are mainly adopted from the literature reported optimization results with a little modification to the Al-Bi-Sn and the Al-Mg-Sn systems for the compatibility of all the constituent binary systems. The assessment results of the Al-Bi-Mg ternary system are in good agreement with the available experimental phase relations, including the liquidus surface projection and the vertical sections. The thermodynamic database of the Al-Bi-Mg-Sn quaternary system was developed without the consideration of the quaternary interactions and the quaternary compounds. With this newly developed thermodynamic database, the phase equilibria and the solidification processes of the ternary and the quarternary systems are calculated and analyzed.

      PubDate: 2017-12-13T09:33:36Z
  • Experimental investigation and simulation of precipitation evolution in
           Mg-3Nd-0.2Zn alloy
    • Abstract: Publication date: March 2018
      Source:Calphad, Volume 60
      Author(s): Xiangyu Xia, Amirreza Sanaty-Zadeh, Chuan Zhang, Alan A. Luo, Donald S. Stone
      In this research, precipitation evolution and strengthening behavior in Mg-3Nd-0.2Zn alloy during isothermal age treatment at 200°C are quantitatively studied by a combination of experimental investigation and computational simulation. Microstructure evolution, including volume fraction, number density, and size of precipitates are first measured by TEM and DSC techniques and then modeled using an integrated computational simulation method combining the CALPHAD (CALculation of PHAse Diagram) approach and classical nucleation model. The focus of the analysis is set on the evolution of key strengthening precipitate β’. Critical kinetic parameters such as particle interfacial energy and nucleation site number are obtained computationally by fitting the model to the experimental data. Mechanical properties of a series of Mg-Nd-Zn alloys are predicted using the simulated microstructure evolution as inputs. Good agreement is found between simulated and measured results. Strategies for enhancing the precipitation hardening effect are presented and discussed based on the simulation results. The merit of this study is to use the obtained parameters to extrapolate microstructure evolution and mechanical properties when adjusting alloy composition and/or heat treatment conditions within a certain range, which will be very useful for further development and optimization of multi-component Mg alloys.

      PubDate: 2017-12-13T09:33:36Z
  • Genetic programming based models for prediction of vapor-liquid
    • Abstract: Publication date: March 2018
      Source:Calphad, Volume 60
      Author(s): Veena Patil-Shinde, Sanjeev S. Tambe
      The design, operation, and control of chemical separation processes heavily rely on the knowledge of the vapor-liquid equilibrium (VLE). Often, conducting experiments to gain an insight into the separation behavior becomes tedious and expensive. Thus, standard thermodynamic models are used in the VLE prediction. Sometimes, exclusively data-driven models are also used in VLE prediction although this method too possesses drawbacks such as a trial and error approach in specifying the data-fitting function. For overcoming these difficulties, this paper employs a machine learning (ML) formalism namely “genetic programming (GP)” possessing certain attractive features for the VLE prediction. Specifically, three case studies have been performed wherein GP-based models have been developed using experimental data, for predicting the vapor phase composition of a ternary, and a group of non–ideal binary systems. The inputs to models consists of three pure component attributes (acentric factor, critical temperature, and critical pressure), and as many intensive thermodynamic parameters (liquid phase composition, pressure, and temperature). A comparison of the VLE prediction and generalization performance of the GP-based models with the corresponding standard thermodynamic models reveals that the former class of models possess either superior or closely comparable performance vis-a-vis thermodynamic models. Noteworthy features of this study are: (i) a single GP-based model can predict VLE of a group of binary systems, and (ii) applicability of a GP-based model trained on an alcohol-acetate series data for its higher homolog. The VLE modeling approach exemplified here can be gainfully extended to other ternary and non-ideal binary systems, and for designing corresponding experiments in different pressure and temperature ranges.

      PubDate: 2017-12-13T09:33:36Z
  • Experimental reinvestigation and thermodynamic description of Bi-Te binary
    • Abstract: Publication date: March 2018
      Source:Calphad, Volume 60
      Author(s): Cun Mao, Mingyue Tan, Ligang Zhang, Di Wu, Weiming Bai, Libin Liu
      The Bi-Te phase diagram was determined by equilibrium alloy method, combined with electron probe microanalysis (EPMA), X-ray diffraction (XRD) and thermal analysis (DSC). The experimental result shows that there is a β-phase with a large composition range at low temperature, while Bi2Te and Bi4Te3 are relatively stable in the solid-liquid region. A consistent phase diagram that covers the experimental findings has been achieved. Based on the new experimental phase diagram, coupling with the reported thermodynamic data, the thermodynamic optimization of the Bi-Te binary system was carried out with the help of CALPHAD approach. A group of reasonable thermodynamic parameters was obtained.

      PubDate: 2017-12-13T09:33:36Z
  • Reconciling SGTE and ab initio enthalpies of the elements
    • Abstract: Publication date: March 2018
      Source:Calphad, Volume 60
      Author(s): Axel van de Walle
      The CALPHAD framework is built on assumption that all phases have a well-defined free energy over all accessible composition, temperature and pressure conditions. Unfortunately, it is common for phases to exhibit mechanical instabilities in at least some range of conditions, thus precluding direct experimental measurements and hindering computational efforts. A pragmatic solution has often been to extrapolate free energies from stable region into the unstable regions, but extrapolations from different systems that share a common phase may not agree and extrapolated free energies can unintentionally lie below the free energy of stable phases. Computational approaches that aim to directly calculate the free energy of unstable phases offer a promising avenue to address these issues. Among them, the recently proposed “inflection detection” scheme lies on a strong theoretical footing. We provide further support for this approach by demonstrating that it yield free energies that agree very well with the widely used SGTE (Scientific Group Thermodata Europe) data for pure elements. This finding suggest that it may be possible to get the best of both worlds: obtain a theoretically justified definition of the free energy of mechanically unstable phases and preserve much of existing empirical standards for the assignments of such free energies.
      Graphical abstract image Highlights fx1

      PubDate: 2017-11-16T10:46:39Z
  • Density functional study of the thermodynamic properties and phase diagram
           of the magnesium hydride
    • Abstract: Publication date: March 2018
      Source:Calphad, Volume 60
      Author(s): Hasan S. AlMatrouk, Viorel Chihaia, Valentin Alexiev
      This paper focuses primarily on the P-T phase diagram determination by considering six polymorphs of magnesium hydride (α - rutile TiO2, P4 2 /mnm, β - cubic modified CaF2, Pa 3 ¯ , γ - orthorhombic PbO2, Pbcn, δ' - orthorhombic, Pbca and cubic - Fm 3 ¯ m). The Gibbs free energy and other thermodynamic properties were evaluated by DFT-based thermodynamic calculations, within the frame of the quasi-harmonic approximation, for the pressure range 0–10GPa and temperatures between 0 and 1200K. Furthermore, the structural, energetic, and electronic properties of the investigated structures are conversed.

      PubDate: 2017-11-16T10:46:39Z
  • Thermodynamic modeling of the V-Si-B system
    • Abstract: Publication date: December 2017
      Source:Calphad, Volume 59
      Author(s): Antonio Augusto Araujo Pinto da Silva, Nabil Chaia, Flavio Ferreira, Gilberto Carvalho Coelho, Jean-Marc Fiorani, Nicolas David, Michel Vilasi, Carlos Angelo Nunes
      In the present work, the V-Si-B ternary system was thermodynamically modeled using the CALPHAD method. The thermodynamic descriptions of the V-Si and B-Si binary systems were taken from literature while the parameters of binary V-B were re-evaluated, based on new experimental information. The ternary thermodynamic description was based on experimental data of isothermal section and liquidus projection. The binary compounds V3B2, VB, V5B6, V3B4, V2B3 and VB2 were modeled as stoichiometric phases; the terminal solid solutions BCC and β-Rhomb were modeled using the sublattice models (V,Si)1(B,va)3 and (B)93(B, Si)12; the ternary phases D88 and T2 were modeled as (V)0.5556(B,Si)0.3333(B,va)0.1111 and (V)0.625(B,Si)0.375, respectively. A set of thermodynamic parameters is proposed and the results showed a good agreement with available experimental information from the literature.

      PubDate: 2017-11-09T09:20:00Z
  • First-principles calculations and thermodynamic modeling of the Yb-Ni
           binary system
    • Abstract: Publication date: December 2017
      Source:Calphad, Volume 59
      Author(s): Yong-Jie Hu, Yi Wang, Samad A. Firdosy, Kurt E. Star, Jean-Pierre Fleurial, Vilupanur A. Ravi, Zi-Kui Liu
      A complete thermodynamic description of the Yb-Ni binary system is developed by means of the CALculation of PHAse Diagram (CALPHAD) method in combination with first-principles calculations based on density functional theory (DFT) and available experimental data in the literature. Finite temperature thermodynamic properties of the Yb-Ni intermetallic compounds are predicted using the quasi-harmonic approach, where first-principles phonon calculations are performed to calculate the lattice vibrational entropy. The associate solution model is used to describe the complex thermodynamic behavior of the liquid phase. The calculated phase diagram agrees well the experimental phase equilibrium data in the literature. By the coupling of CALPHAD modeling with first-principles calculations, the present work provides a more thermodynamically accurate model of the Yb-Ni system when compared to previous models.

      PubDate: 2017-11-09T09:20:00Z
  • Thermodynamic re-assessment of the Fe-Dy and Fe-Tb binary systems
    • Abstract: Publication date: December 2017
      Source:Calphad, Volume 59
      Author(s): M.H. Rong, X.L. Chen, J. Wang, G.H. Rao, H.Y. Zhou
      In this work, based on the critical evaluation of previous optimizations and available experimental data in the published literature, the Fe-Dy and Fe-Tb binary systems were re-assessed thermodynamically using the CALPHAD method. The solution phases including liquid, fcc-Fe, bcc-Fe, bcc-Dy, bcc-Tb, hcp-Dy and hcp-Tb, were described by the substitutional solution model and their excess Gibbs energies were expressed with the Redlich-Kister polynomial. Due to their narrow homogeneity ranges, the intermetallic compounds, Fe17Dy2, Fe23Dy6, Fe3Dy, Fe2Dy, Fe17Tb2, Fe23Tb6, Fe3Tb and Fe2Tb, were modeled as stoichiometric compounds. Self-consistent thermodynamic parameters to describe the Gibbs energies of various phases in the Fe-Dy and Fe-Tb binary systems were obtained finally. The calculated results are in good agreement with the reported phase equilibria and thermodynamic properties.

      PubDate: 2017-11-02T09:09:19Z
  • Numerical modelling of moving interfaces under local equilibrium
    • Abstract: Publication date: December 2017
      Source:Calphad, Volume 59
      Author(s): Jae Sang Lee, Dong-Woo Suh, Yang Mo Koo, Seong Gyoon Kim
      A new method is presented to simulate moving interfaces during diffusion-controlled growth under local equilibrium conditions. The position and compositions of the interface are obtained directly from the equilibrium state of the subsystem around the moving interface, without iterative calculation between diffusion fluxes and solute balance conditions. The method is applicable to general multi-component systems, and it ensures the consistency in compositions and solute balance at the interfaces; Those are ascribed to the presented consideration of subsystem around the interface region in a discretized form. Explicit equations of interface compositions and position in discretized variables are also presented for the simplified ternary systems of two-solution and compound/solution. The validity and usefulness of the method is demonstrated by simulations of the two important ternary systems; The simulation results illustrate the features of diffusion-controlled growth with different alloy compositions and diffusivities of solutes in both systems.
      Graphical abstract image

      PubDate: 2017-11-02T09:09:19Z
  • Thermodynamic modeling of phase equilibria and defect chemistry in the
           Zn-S system
    • Abstract: Publication date: December 2017
      Source:Calphad, Volume 59
      Author(s): Pin-Wen Guan, Shun-Li Shang, Greta Lindwall, Tim Anderson, Zi-Kui Liu
      Though important and fundamental, a satisfactory theoretical framework of modeling multiple point defects in the context of phase equilibria is still lacking. In this work, a methodology that models point defects, electrons, holes and the underlying phase equilibria simultaneously is developed and applied to the Zn-S system. It overcomes some issues in previous works, such as inconsistency in the reference state for electrons. The model parameters are directly related to the Gibbs energy of formation of point defects computed from first-principles phonon calculations. A double exponential function is proposed to parameterize the entropy of formation of point defects as a function of temperature. Using this approach, phase diagrams, concentrations of point defects and free carriers, the majority carrier, and defect-related properties exemplified by the electrical conductivity are obtained under various conditions, in agreement with experimental data. The present methodology provides a way to integrate first-principles calculations and experimental data into the CALPHAD model, enabling description of multi-component semiconductor systems.

      PubDate: 2017-11-02T09:09:19Z
  • Phase relations in the Cu-O-Al2O3-SiO2 system at 1150°C and
           1300°C in air
    • Abstract: Publication date: December 2017
      Source:Calphad, Volume 59
      Author(s): Niko Hellstén, Pekka Taskinen
      Phase equilibria of the Cu-O-Al2O3-SiO2 system are important in the processing of copper aluminosilicate glasses, mullite ceramics and in non-ferrous metallurgy. We experimentally investigated the phase equilibria of this system at 1150°C and 1300°C in air atmosphere using equilibration and quenching method. Chemical compositions of the liquid and solid phases in the quenched samples were determined by Electron Probe Microanalysis (EPMA). Based on the results, we constructed an isothermal section containing the liquidus contours of various primary phases at 1300°C. Comparison of these results with previous experimental work confirms that oxygen pressure affects phase stability and composition of the liquidus in this system. The experimental liquidus determined in this work disagrees by up to 50wt% with the calculated values of MTDATA 6.0 software and Mtox database version 8.2. Concentration of ‘Cu2O′ in mullite ranged from 0.46wt% to 1.25wt%. The results of this work will enable improvement of thermodynamic descriptions for this system.

      PubDate: 2017-11-02T09:09:19Z
  • Experimental investigation and thermodynamic calculation of the B-Fe-Mo
           ternary system
    • Abstract: Publication date: December 2017
      Source:Calphad, Volume 59
      Author(s): Xuemei Ou Yang, Fucheng Yin, Jingxian Hu, Manxiu Zhao, Ye Liu
      The phase relationship of the B-Fe-Mo ternary system has been investigated combining experimental results with thermodynamic modeling. The liquidus projection of the ternary system in the Fe-rich region was constructed by identifying primary crystallization phases in the as-cast alloys and determining liquid temperatures obtained from the DSC analyses. Eight different primary solidification regions were observed, and they are BCC, FCC, Mo2FeB2, Fe2B, FeB, σ, and R, respectively. And four invariant reactions were identified in the Fe-rich region. Thermodynamic optimization of the B-Fe-Mo ternary system was performed using CALPHAD approach based on the thermodynamic models of the three constitutional binary systems and the experimental results of the ternary system. A set of self-consistent thermodynamic parameters for the B-Fe-Mo system were obtained with reasonable agreement between the experimental and calculated results.

      PubDate: 2017-11-02T09:09:19Z
  • CALPHAD modeling of metastable phases and ternary compounds in Ti-Al-N
    • Abstract: Publication date: December 2017
      Source:Calphad, Volume 59
      Author(s): Yanhui Zhang, Peter Franke, Hans Jürgen Seifert
      The development and evaluation of thermodynamic databases for the Ti-Al-N system is important for a wide range of engineering alloys. In this work, we resorted to the integration of ab initio thermodynamics, experiments and CALPHAD modeling for a comprehensive understanding of the metastable and the ternary phases in Ti-Al-N system. The supersaturated solutions of (Ti,Al)N with both rocksalt and wurtzite structures were well described by using the sub-regular solution model. Thereby, the formation, the phase separation and the meta-solubility of TiAlN coatings were successfully elaborated by the metastable pseudo-binary TiN-AlN section and the PVD (physical vapor deposition) phase diagram. Moreover, a number of isothermal and isopleth sections were also calculated and compared with available experiments and previous thermodynamic assessments. For the first time the ternary compound of τ 3 was corrected as Ti 4 AlN 3 in our proposed database.

      PubDate: 2017-10-14T14:28:02Z
  • Thermodynamic re-assessment of the Al-Co-W system
    • Abstract: Publication date: December 2017
      Source:Calphad, Volume 59
      Author(s): Peisheng Wang, Wei Xiong, Ursula R. Kattner, Carelyn E. Campbell, Eric A. Lass, Oleg Y. Kontsevoi, Gregory B. Olson
      The Al-Co-W system and its binary sub-systems Al-Co, Al-W and Co-W were critically reviewed. The thermodynamic description of the Al-Co-W system including all three binaries was developed considering thermodynamic and constitutional data of the systems. Results from density functional theory calculations were employed to improve reliability of the descriptions. The Gibbs energy for the thermal vacancy (GVa) in the BCC_A2 phase is discussed. The revised descriptions obtained for the Al-W and Co-W systems describe the thermodynamic and phase equilibrium data well and are free of undesired artefacts for temperatures below 6000K. The ordered γ’ phase of the Al-Co-W system is described as a metastable phase in the entire temperature range. The calculated Gibbs energy of the γ’ is only slightly above that of the equilibrium state, which indicates that there is good possibility of stabilizing the γ’ phase with the addition of γ’-stabilizing elements, such as Ti, Ta, Hf, Nb and Ni.

      PubDate: 2017-10-11T14:13:11Z
  • Second nearest-neighbor modified embedded-atom method interatomic
           potentials for the Pt-M (M = Al, Co, Cu, Mo, Ni, Ti, V) binary systems
    • Abstract: Publication date: December 2017
      Source:Calphad, Volume 59
      Author(s): Jin-Soo Kim, Donghyuk Seol, Joonho Ji, Hyo-Sun Jang, Yongmin Kim, Byeong-Joo Lee
      Interatomic potentials for Pt-M (M = Al, Co, Cu, Mo, Ni, Ti, V) binary systems have been developed on the basis of the second nearest-neighbor modified embedded-atom method (2NN MEAM) formalism. The parameters of pure Mo have also been newly developed to solve a problem in the previous 2NN MEAM potential in which the sigma and α-Mn structures become more stable than the bcc structure. The potentials reproduce various materials properties of alloys (structural, thermodynamic and order-disorder transition temperature) in reasonable agreements with relevant experimental data and other calculations. The applicability of the developed potentials to atomistic investigations for the shape and atomic configuration of Pt bimetallic nanoparticles is demonstrated.

      PubDate: 2017-10-11T14:13:11Z
  • A new thermodynamic description of stable Cr-carbides for the third
           generation of thermodynamic database
    • Abstract: Publication date: December 2017
      Source:Calphad, Volume 59
      Author(s): Zhou Li, Huahai Mao, Malin Selleby
      An updated thermodynamic description of the stable Cr-carbides was obtained by applying the same models as used for the elements within the 3rd generation of thermodynamic databases. The Einstein model was used and a scaling factor was introduced to take into account the coupling effect between the stoichiometry (C to Cr ratio) and the structure of the compound. Using this model we could accurately describe the thermodynamic properties of these stoichiometric compounds using available experimental heat capacity data. The new description is now more physically sound and results in a better agreement with the experimental heat capacity data.

      PubDate: 2017-10-03T13:00:11Z
  • Thermodynamic modeling of the Ta–Mo–C ternary system
    • Abstract: Publication date: December 2017
      Source:Calphad, Volume 59
      Author(s): Cong Zhang, Haiqing Yin, Yong Du, Yafei Pan, Peng Deng
      The Ta–Mo–C system was assessed by means of the CALPHAD approach. All of the phase diagram and thermodynamic information available from the literature were critically reviewed. The liquid was modeled as substitutional solution phase, while the carbides including fcc-(Mo,Ta)C1-x , bcc-(Mo,Ta), hcp-(Mo,Ta)2C and η-MoC were described by using corresponding sublattice models. The ζ-Ta4C3-x was considered as a linear compound with carbon content fixed, while shp-MoC was treated to be a binary stoichiometric phase. There was no ternary compound reported in this system. The modeling of Ta–Mo–C ternary system covers the entire composition and temperature ranges, and a set of self-consistent thermodynamic parameters for the Ta–Mo–C system was systematically optimized. Comprehensive comparisons between the calculated and reported phase diagram and thermodynamic data show that the reliable information is satisfactorily accounted for by the present modeling. The liquidus projection and reaction scheme of the Ta–Mo–C system were also generated by using the present thermodynamic parameters.

      PubDate: 2017-09-26T12:20:07Z
  • Thermodynamic modeling of the Ca(NO3)2-MNO3 (M: alkali metal) systems
    • Abstract: Publication date: December 2017
      Source:Calphad, Volume 59
      Author(s): Xiang Li, Kun Wang, Miao Shen, Zhu Wu, Leidong Xie
      This work presents a thermodynamic evaluation of the Ca(NO3)2-MNO3 (M: Li, Na, K, Rb, Cs) binary systems using the CALPHAD approach. The required Gibbs energy of liquid Ca(NO3)2 is missing in the literature and has been successfully evaluated in the present work with a fusion enthalpy of 23849Jmol−1. The substitutional solution model can thus be employed to describe the Ca(NO3)2-base liquid phase. All the intermediate compounds are treated to be stoichiometric and their Gibbs energies comply with the Neumann-Kopp rule. Empirical functions relating mixing enthalpies to ionic parameters are employed to predict the corresponding values of binary melts which are used as input data to assist in parameters optimization for the liquid phases. The final calculated results show good agreement with most of the experimental and predicted data.

      PubDate: 2017-09-19T14:40:54Z
  • Diffusivities and atomic mobilities for fcc Cu–Ni–Sn alloys
    • Abstract: Publication date: December 2017
      Source:Calphad, Volume 59
      Author(s): Yuling Liu, Chong Chen, Dandan Liu, Yong Du, Shuhong Liu, Xiaoma Tao, Yifang Ouyang
      Utilizing five groups of bulk diffusion couples together with electron probe microanalysis technique, the composition-dependent ternary interdiffusion coefficients in fcc Cu–Ni–Sn alloys at 1023K were determined via the Whittle and Green method. The presently obtained interdiffusion coefficients at 1023K as well as our previously measured ones at 1073K were combined with the slightly modified thermodynamic descriptions of the fcc Cu–Ni–Sn phase to explore atomic mobilities of Cu, Ni and Sn in fcc Cu–Ni–Sn alloys within the CALPHAD framework. In order to be consistent with the thermodynamic description, atomic mobilities in binary fcc Ni–Sn alloys were re-evaluated in the present work. The quality of the assessed kinetic characteristics was confirmed by the comprehensive comparisons between various model-predicted diffusion behaviors and the experimental ones, including concentration profiles and diffusion paths.

      PubDate: 2017-09-14T08:18:29Z
  • Ab initio-assisted assessment of the CaO-SiO2 system under pressure
    • Abstract: Publication date: December 2017
      Source:Calphad, Volume 59
      Author(s): D. Belmonte, G. Ottonello, M. Vetuschi Zuccolini
      We present the results of an ab initio-assisted assessment of melting and subsolidus phase relations in the system CaO-SiO2 up to high pressure conditions. All solid compounds known to nucleate in the system have been treated as purely stoichiometric and the liquid resolved in the framework of a simple polymeric model. Mixing properties of the binary liquid phase are fully described by a single-parameter purely enthalpic chemical interaction plus a strain energy contribution. The latter is required to predict liquid immiscibility of SiO2-rich liquid compositions at ambient conditions and becomes irrelevant at P>2GPa. A detailed survey of thermodynamic properties of silica polymorphs and calcium oxide and silicates in a broad range of P-T conditions reveals quite controversial stability relations and melting behavior. First-principles calculations on CaO and SiO2 pure liquid components and solid phases (lime and stishovite) have been used, along with a sound assessment of first- and second-order phase transitions, to reconcile thermochemical data with topological details of the observed phase diagrams. A physically-consistent coupling between thermodynamic and thermoelastic properties (viz. compressibility and thermal expansion) turns out to be of fundamental importance to infer reliable stability relations both at subsolidus and melting conditions. Pressure effects shift the composition of the main invariant points in the CaO-SiO2 system and also change the melting behavior of the CaSiO3 metasilicate in a complex manner.

      PubDate: 2017-09-02T07:41:30Z
  • Phase equilibria in the ternary Fe-Co-S system
    • Abstract: Publication date: December 2017
      Source:Calphad, Volume 59
      Author(s): Mariia O. Ilatovskaia, Svetlana I. Sinyova, Roman V. Starykh
      The Fe-FeS-CoS-Co system has been investigated experimentally from 1073K up to liquidus temperature. Samples of the system have been investigated using DTA/TGA, SEM/EDX, and XRD methods. Liquidus and solidus projections have been plotted based on experimental data.

      PubDate: 2017-09-02T07:41:30Z
  • Vapor pressure of alkali-metal binary alloys in glass cells
    • Abstract: Publication date: December 2017
      Source:Calphad, Volume 59
      Author(s): Kiyoshi Ishikawa
      The alkali partial pressures of composite alkali-metal vapor are crucial in atomic-physics optical experiments. The vapor pressures of alkali-metal binary alloys can be calculated by using the activity and the mixing enthalpy for homogeneous alloys from early measurements. We show that the results of sodium-containing alloys deviate appreciably from the prediction of Raoult's law. Experimentally, the phase and the mixing ratio of binary alloys are non-destructively measured by nuclear-magnetic-resonance spectroscopy in glass cells. We find that many droplets of the sodium-rubidium alloy exist on the cell walls, and they have different mixing ratios. Therefore, the vapor density varies microscopically around the glass cells. To achieve precision optical measurements, we should take account of the pressure change due to the equilibrium process and further sodium contamination over the lifetime of glass cells.

      PubDate: 2017-09-02T07:41:30Z
  • The reassessment of the Al-V system and new assessment of the Al-Si-V
    • Abstract: Publication date: December 2017
      Source:Calphad, Volume 59
      Author(s): A. Kroupa, M. Mazalová, K.W. Richter
      The theoretical assessment of the Al-Si-V system has been carried out and has been presented here. The experimental results from Huber et al. [1,2] were used as the basis of the assessment. The relevant binary system assessments for Al-V [9], Al-Si [13] and Si-V [14] were used in the initial stage of the study and it was found that complete reassessment of the Al-V system was necessary. The reassessed dataset for the Al-V system is in very good agreement not only with existing experimental phase diagram and thermodynamic data, but is also consistent with the independent work of Lindahl et al. [22]. The final assessment of the Al-Si-V system using our own reassessed Al-V system is in excellent agreement with the experimental data.

      PubDate: 2017-09-02T07:41:30Z
  • Thermodynamic reassessment of the novel solid-state thermal energy storage
           materials: Ternary polyalcohol and amine system
    • Abstract: Publication date: December 2017
      Source:Calphad, Volume 59
      Author(s): Renhai Shi, Dhanesh Chandra, Amrita Mishra, Anjali Talekar, Muralidhar Tirumala, Daryl J. Nelson
      Organic polyalcohol and amine globular molecular crystals such as PG, TRIS, and NPG are considered as the most promising potential candidates for solid-state thermal energy storage in the orientationally disordered high temperature phases. In this study, we first propose a new PG-TRIS-NPG phase diagram based on experimental data of the three sub-binary systems NPG-PG, PG-TRIS, and NPG-TRIS with CALPHAD methodology. The NPG-PG binary phase diagram was optimized using sub-regular models that showed complete miscibility in the entire compositional range of high temperature γ′ (FCC) phase region, and an invariant equilibrium point at 299.5K. The NPG-TRIS binary system was also calculated using sub-regular model, from sub-ambient to well above the melting temperatures, and determined three invariant equilibria at 311.1K, 391.8K, and 410.6K, respectively. These calculated binary phase diagrams are in good agreement with the experimental data. The PG-TRIS-NPG ternary system has also been calculated and qualitatively analyzed using the CALPHAD method and Thermo-Calc software. A set of self-consistent thermodynamic parameters formulating the Gibbs energies of various phase in the PG-TIRS-NPG ternary system are obtained in the present work. Thermodynamic properties such as several isotherms, isopleths, and liquidus projections are calculated by using present datasets as shown in this work in which the solid ternary compound (TRIS0.5NPG0.5)XPG1−X (0.1≤x≤0.9), (TRIS0.5PG0.5)XNPG1−X (0.1≤x≤0.9), and (PG0.5NPG0.5)XTRIS1−X (0.1≤x≤0.9) with various solid-solid phase transitions at different temperatures could apply to applications in the solid-state thermal energy storage.

      PubDate: 2017-09-02T07:41:30Z
  • A method of integrating CALPHAD data into phase-field models using an
           approximated minimiser applied to intermetallic layer growth in the Al-Mg
    • Abstract: Publication date: December 2017
      Source:Calphad, Volume 59
      Author(s): M.J. Welland, M.H.A. Piro, S. Hibbins, N. Wang
      This article describes an approach to combine single phase thermodynamic potentials into a multiphase composite potential suitable for integration in a multicomponent phase-field model. The composite potential avoids implicit interfacial energy contributions by starting from a grand potential formulation. The method is made explicit by expanding the minimiser resulting from the Legendre transform between grand and Helmholtz potentials about a known equilibrium state. The resulting composite function is explicit, reproduces the equilibrium states exactly, and is smooth such that it can be differentiated to provide the driving forces for mass transport and phase change in a thermodynamically self-consistent manner. The model is demonstrated by simulating a sequence of phase transformations for intermetallic growth in Al-Mg interdiffusion for advanced nuclear research reactor fuel.

      PubDate: 2017-09-02T07:41:30Z
  • Critical assessment and thermodynamic modeling of the
           Cu–Fe–O–Si system
    • Abstract: Publication date: September 2017
      Source:Calphad, Volume 58
      Author(s): Taufiq Hidayat, Denis Shishin, Sergei A. Decterov, Evgueni Jak
      The present study is the first Calphad-type assessment of the Cu–Fe–O–Si system. All relevant thermodynamic and phase equilibrium data have been critically evaluated to produce a thermodynamic database describing the Gibbs energies of all phases in the system. The predictive range of the database covers all conditions of pyrometallurgical production of copper in terms of temperature and oxygen partial pressure. Liquid oxide slag and liquid metal phases have been described using two separate solution models, both developed within the framework of the Modified Quasichemical Formalism. Slag model is expressed as [Cu+, Fe2+, Fe3+, Si4+][O2-] and metal model is expressed as (CuI, FeII, OII). They are internally consistent with the models for fcc–Cu, fcc–Fe, bcc–Fe, spinel, wüstite, CuFeO2, Cu2O, Fe2SiO4, Fe2O3 and SiO2 obtained in the previous optimizations of the Cu–O, Fe–O, Cu–Fe, Cu–Fe–O, Cu–O–Si, Fe–O–Si sub-systems.

      PubDate: 2017-09-02T07:41:30Z
  • Critical evaluation of thermodynamic properties of rare earth sesquioxides
           (RE = La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sc and
    • Abstract: Publication date: September 2017
      Source:Calphad, Volume 58
      Author(s): Yumin Zhang, In-Ho Jung
      In order to develop the thermodynamic database containing rare earth sesquioxides (RE2O3), accurate thermodynamic descriptions of all stable and metastable RE2O3 phases are required. Rare earth sesquioxides have five polymorphs, which are (from low to high temperature) the cubic phase (C), the monoclinic phase (B), the hexagonal phase (A), the high temperature hexagonal phase (H), and the high temperature cubic phase (X). However, the thermodynamic property data of all polymorphs available in the literature are insufficient. In particular, the thermodynamic data for the phases stable only at high temperatures and for metastable phases are not well investigated. In this study, all ∆ H 298 K o , S 298 K o , C P (or heat content) and phase transition temperature (T tr ) data available in the literature for each rare earth sesquioxide were collected and critically evaluated based on the sample preparations, experimental procedures and characterization techniques. Relationships between ∆ H 298 K o , S 298 K o , and T tr against the ionic radii of the entire rare earth cations were then established and missing thermodynamic information was predicted based on the general trends. In these ways, the accurate and consistent Gibbs energies of all stable and metastable RE2O3 phases (RE = La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Y and Sc) were prepared. These Gibbs energy data can be readily used for the development of a comprehensive thermodynamic database containing rare earth oxides.

      PubDate: 2017-09-02T07:41:30Z
  • Calorimetric measurement of the standard enthalpy of formation of ZnSb at
           298 K
    • Abstract: Publication date: September 2017
      Source:Calphad, Volume 58
      Author(s): P. Benigni, A. Berche, R. Pothin, A. Adenot, G. Mikaelian, R.M. Ayral, P. Jund, J. Rogez
      After a critical review of the literature data on the standard enthalpy of formation of ZnSb, discrepancies between various experimental studies are highlighted. Moreover, experimental values disagree with values calculated by ab initio methods. As many of the experimental methods used suffer from some serious drawbacks, a new determination of the standard enthalpy of formation of ZnSb by an alternative calorimetric method, drop solution calorimetry in liquid tin, has been performed. Two different synthesis methods have been used to obtain a pure ZnSb phase and drop solution experiments were performed at 665 and at 974K. The standard enthalpy of formation values derived from these experiments are − 6.1±2.5kJmol of atoms−1 for the ZnSb sample prepared by ball milling and − 7.9±0.4kJmol of atoms−1 for the ZnSb sample prepared by melting. These results are discussed and compared to literature data.

      PubDate: 2017-09-02T07:41:30Z
  • Experimental investigation and thermodynamic description of the Cu-Cr-Zr
    • Abstract: Publication date: December 2017
      Source:Calphad, Volume 59
      Author(s): Yuling Liu, Peng Zhou, Shuhong Liu, Yong Du
      The Cu-Cr-Zr ternary system was investigated via thermodynamic modeling coupled with key experiments. The isothermal section of the Cu-Cr-Zr system at 1123K was determined by means of optical microscopy, X-ray diffraction and electron probe microanalysis, and the phase transformation temperatures were measured by differential scanning calorimetry. The Cu-Cr sub-binary system was re-assessed with a substitutional solution model for the solution phases to ensure its compatibility in multi-component system. A set of self-consistent thermodynamic parameters for the Cu-Cr-Zr systems was obtained using the CALPHAD (CALculation of PHAse Diagram) approach, and the calculated phase diagram is in a satisfactory agreement with the present experimental results and literature information. An increase of the thermodynamic stability for the CuZr and Cr2Zr phases due to the ternary solubility is verified by calculation.

      PubDate: 2017-08-03T11:16:57Z
  • Thermodynamic description of the Al–Ge–Ni system over the whole
           composition and temperature ranges
    • Abstract: Publication date: September 2017
      Source:Calphad, Volume 58
      Author(s): Chenyang Zhou, Jiaxin Cui, Cuiping Guo, Changrong Li, Zhenmin Du
      The phase equilibria and thermodynamic properties of the Al–Ge–Ni system are useful for understanding the diffusion process during the transient liquid phase (TLP) bonding. In this work, the thermodynamic description of the Al–Ge–Ni system over the whole composition and temperature ranges was performed by means of the CALPHAD (CALculation of PHAse Diagrams) method. The enthalpies of mixing of the liquid phase, three isothermal sections at 973, 823, and 673K and nine vertical sections at 10, 20, 35, 55, 60, 70, 75, and 80at% Ni and at a constant Al:Ni ratio of 1:3 were taken into account in the present optimization work. A set of self-consistent thermodynamic parameters of the Al–Ge–Ni system was first obtained. The liquidus projection and reaction scheme were constructed according to the thermodynamic parameters obtained in this work. The phase equilibria and thermodynamic properties calculated by the present thermodynamic description show satisfactory agreement with the available experimental information.

      PubDate: 2017-07-24T11:01:09Z
  • Thermodynamic re-assessment of the Fe-Gd and Fe-Sm binary systems
    • Abstract: Publication date: September 2017
      Source:Calphad, Volume 58
      Author(s): X.L. Chen, J. Wang, T.L. Chen, X.D. Lin, M.H. Rong, G.H. Rao, H.Y. Zhou
      The Fe-Gd and Fe-Sm binary systems were re-assessed thermodynamically using the CALPHAD method based on the critical evaluation of previous optimizations and available experimental information in the published literature. The solution phases including liquid, fcc-Fe, bcc-Fe, bcc-Gd, hcp-Gd, bcc-Sm, hcp-Sm and rhombohedral-Sm, were described by the substitutional solution model and their excess Gibbs energies were expressed with the Redlich-Kister polynomial. The intermetallic compounds, α-Fe17Gd2, β-Fe17Gd2, Fe23Gd6, Fe3Gd, Fe2Gd, Fe17Sm2, Fe3Sm and Fe2Sm, were modeled as stoichiometric compounds due to their narrow homogeneity ranges. Self-consistent thermodynamic parameters to describe Gibbs energies of various phases in the Fe-Gd and Fe-Sm binary systems were obtained finally. The calculated results in this work are in good agreement with the reported phase equilibria and thermodynamic properties.

      PubDate: 2017-07-24T11:01:09Z
  • Investigation of the phase equilibria in Ti-Ni-Hf system using diffusion
           triples and equilibrated alloys
    • Abstract: Publication date: September 2017
      Source:Calphad, Volume 58
      Author(s): J.L. Liu, L.L. Zhu, X.M. Huang, G.M. Cai, Z.P. Jin
      In present work, the phase equilibrium relations in the Ti-Ni-Hf ternary system, which are of great importance for the design of Ti-Ni based high temperature shape memory alloys, were investigated using diffusion triples and sixteen key equilibrated alloys. Based on the experimental results from electron-probe microscopy analysis (EPMA) and X-ray diffraction (XRD) techniques, two isothermal sections were constructed, which consist of 13 and 12 three-phase regions at 900°C and 800°C, respectively. Hf can substitute for Ti in TiNi and Ti2Ni phases increasing from 30, 62at% at 800°C to 36, 64at% at 900°C, respectively. The Hf7Ni10 and Hf9Ni11 phases show wide ternary composition ranges, while the solubility of Ti in HfNi5, Hf2Ni7, and HfNi phases are relatively limited. A new ternary phase of τ was detected for the first time, and the stoichiometry of τ phase is close to Ni:(Hf,Ti) = 11:14, with Ti substituting for Hf from ~5at% to ~22at%. The single-phase region of the τ phase became narrow as the decreasing of annealing temperature. Based on comparison of phase relations at 900°C and 800°C, it is speculated there is an invariant reaction TiNi + τ → HfNi + Ti2Ni at between 900°C and 800°C.
      Graphical abstract image

      PubDate: 2017-07-24T11:01:09Z
  • Experimental investigations and DICTRA® simulation of sigma phase
           formation in a duplex stainless steel
    • Abstract: Publication date: September 2017
      Source:Calphad, Volume 58
      Author(s): Luara da Costa Morais, Rodrigo Magnabosco
      Sigma phase formation in an UNS S31803 duplex stainless steel aged at 940°C was evaluated by computational simulation in DICTRA® software, using MOB2 diffusion database and TCFE8 thermodynamic database. Simulation results were compared to experimental tests. Two models were tested in DICTRA® software: in model 1 sigma phase are placed between ferrite and austenite, and in model 2 sigma is placed at one side of ferrite region, and austenite on the other. The volume fraction of sigma and ferrite phases obtained in model 1 showed adherence to the experimental results up to 7200s (2h) of simulation, indicating the ability of the model in the description of early stages of sigma formation. Model 2 showed good agreement with experimental data up to 86,400s (24h) of simulation. The composition profile obtained by the simulation of the model 1 represented better the impoverishment in Cr and Mo in ferrite/sigma and austenite/sigma interfaces, while the profiles obtained by the simulation of model 2 described better the partition of the chemical elements between austenite and ferrite during sigma formation.

      PubDate: 2017-07-24T11:01:09Z
  • Ti-17 volatilization under vacuum: Investigation of the activity
           coefficients at 1900°C
    • Abstract: Publication date: September 2017
      Source:Calphad, Volume 58
      Author(s): Colin Reimer, Julien Jourdan, Jean-Pierre Bellot
      Vacuum processing techniques are a valuable industrial tool for the processing of reactive metals and alloys. However, drawbacks caused by the selective volatilization of alloying elements lead to an hard prediction of final alloy composition. By understanding the behaviour of the alloying elements and the interactions between them, improved compositional accuracy can be achieved. The evaluation of the activity coefficients is a key property that relates partial vapor pressure with the Langmuir law to accurately predict the mass flux of the individual elements in an alloy. This study takes a look at the grade Ti-17 which exhibits a relative large number of alloying elements. By using an electron beam furnace and a vapor deposition apparatus the necessary measurements were made to evaluate activity coefficients for each of the volatizing elements in the alloys including Aluminum, Chromium, Tin. Comparisons were made between experiments and the findings suggest that the primary interactions between the alloying elements with titanium result in small deviations between alloys. The results for the experiments provided reliable and repeatable results.

      PubDate: 2017-07-12T10:01:11Z
  • Experimental investigation and thermodynamic assessment of the
           Mo–Ni–Zr ternary system
    • Abstract: Publication date: September 2017
      Source:Calphad, Volume 58
      Author(s): Shimin Wang, Cong Zhang, Yong Du, Yingbiao Peng, Yafei Pan, Peng Zhou, Liya Dreval
      The isothermal section of the Mo–Ni–Zr system at 1100°C was investigated by characterization of eight equilibrium alloys. X-ray diffraction (XRD) and electron probe microanalysis (EPMA) were used to identify the stable phases and obtain their compositions. The Mo–Ni–Zr system was then optimized by means of CALPHAD (CALculation of PHAse Diagrams) technique with the consideration of experimental data obtained in the present work and reported in the literature. The liquid, fcc, bcc and hcp solution phases, were modeled with (sub-)regular solution model. The compound Zr65Mo18−xNi16.5+x (τ1, cF96-Ti2Ni) was described as Zr2(Mo, Ni) based on its crystal structure and solubility range. While τ2 (Zr65Mo27.3Ni7.7) phase was modeled as a stoichiometric compound due to its limited homogeneity range. A set of self-consistent thermodynamic parameters for the Mo–Ni–Zr system was finally obtained. Comprehensive comparisons between the calculated and experimental phase diagram data show that the experimental information is satisfactorily accounted for by the present thermodynamic description. The liquidus projection and reaction scheme of the Mo–Ni–Zr system were also generated by using the present thermodynamic parameters.

      PubDate: 2017-07-12T10:01:11Z
  • Updating the estimated assemblage of stable phases in a Gibbs energy
    • Abstract: Publication date: September 2017
      Source:Calphad, Volume 58
      Author(s): M.H.A. Piro
      Several numerical strategies are presented that can be used to effectively and efficiently update the estimated assemblage of stable phases in a Gibbs energy minimizer. Decisions must be made in selecting which phase should be added to or withdrawn from the system, the order in which certain combinations should be considered, testing procedures of the appropriateness of a candidate system for further consideration, etc. The manner in which these methods are performed have a profound effect on the performance and reliability of such calculations; without effective strategies, the solution may not converge. While these matters are somewhat straightforward for relatively small systems, far greater challenges are experienced in large systems containing many chemical elements. These matters will be discussed and effective solutions that have been integrated into thermochimica throughout the course of its development will be presented.

      PubDate: 2017-07-03T09:07:26Z
  • Software tools for high-throughput CALPHAD from first-principles data
    • Abstract: Publication date: September 2017
      Source:Calphad, Volume 58
      Author(s): Axel van de Walle, Ruoshi Sun, Qi-Jun Hong, Sara Kadkhodaei
      We present a set of software tools that largely automate the process of converting ab initio data into thermodynamic databases that can readily be imported into standard thermodynamic modeling softwares. These tools are based on the Special Quasirandom Structures (SQS) formalism, extended to transparently handle, not only traditional fcc, bcc and hcp solid solutions, but also multiple-sublattice structures with possible sublattice disorder. A large database of pre-generated SQS is provided that covers over 30 of the most common multi-sublattice structures and spans the composition ranges of each of their sublattices. In addition, we exploit a theoretically justified and robust method to address the issue of assigning free energies to mechanically unstable “virtual” phases, thus providing a compelling solution to a long-standing problem in CALPHAD modeling, especially in the context of ab initio data. We also propose a simple low-order approximation scheme to include short-range order effects that requires no additional ab initio input. The resulting thermodyamic database seamlessly combines ab initio data (formation energies and, optionally, vibrational free energies) with elemental Scientific Group Thermodata Europe (SGTE) data. The proposed tools provide a clear path to expand the coverage of high-throughput efforts towards non-stoichiometric phases and non-zero temperatures. The generated free energy models can also provide very good starting points to perform complex thermodynamic assessments, especially in cases where the available experimental data poorly constrain some thermodynamic parameters. The Cu-Pt-W phase diagram is calculated as an example.
      Graphical abstract image Highlights fx1

      PubDate: 2017-06-12T07:40:52Z
  • Thermodynamic and diffusion kinetic studies of the Fe-Co system
    • Abstract: Publication date: September 2017
      Source:Calphad, Volume 58
      Author(s): Jingjing Wang, Xiao-Gang Lu, Naqiong Zhu, Weisen Zheng
      The phase equilibria, thermodynamic properties and diffusion mobilities of the Fe-Co system were carefully assessed through the CALPHAD methods. As an indispensable tool, the first-principles calculations were carried out to study the magnetic moments and the enthalpies of mixing of the bcc_A2, bcc_B2, fcc_A1 and hcp_A3 phases as well as the point defect types of the bcc_B2 phase. In order to verify the heat capacities reported in the literature, new measurements were conducted in a high-temperature calorimetric apparatus using the three-dimensional calorimetric method. Because of the revision of the thermodynamic parameters in the present work, the diffusion mobilities for the fcc_A1 phase were reassessed. The diffusion mobilities for the bcc_A2 phase were established for the first time based on the experimental diffusion coefficients. For the low-temperature bcc_B2 phase, the diffusion couple experiments conducted in the present work show that the diffusion process is sluggish and the interdiffusion coefficients are difficult to determine. Therefore the tracer diffusivities of Co and Fe in the Fe-Co alloys were used to assess the diffusion mobilities for the bcc_B2 phase, while the composition-distance profile of one diffusion couple was served as a validation of its diffusion mobilities.

      PubDate: 2017-06-12T07:40:52Z
  • Experimental investigation of phase equilibria in the Ti-Fe-Cr ternary
    • Abstract: Publication date: September 2017
      Source:Calphad, Volume 58
      Author(s): Lijun Zeng, Libin Liu, Shuaixiong Huang, Ligang Zhang
      Phase equilibria in ternary Ti-Fe-Cr system at 873 and 1173K were investigated in this work. Based on the phase constitutions and phase compositions in 32 samples prepared using the equilibrated alloys, the isothermal sections of the Ti-Fe-Cr ternary system were established. For this system, there were six three-phase regions at both 873 and 1173K, the phase relations at the studied two temperatures are almost the same. Thereinto, two tentative three-phase regions of βCr2Ti + β(Ti) + (Fe, Cr)2Ti and βCr2Ti + β(Ti) + αCr2Ti were deduced near the Ti-Cr side at 1173K. The (Fe, Cr)2Ti phase has a large solubility of Cr, up to 59.1at% at 873K and 59.5at% at 1173K. Moreover, at 873 and 1173K, the homogeneity ranges of the nearly linear ternary compounds τ1 were measured to be 49.9–72.1at% Fe and 52.7–77.2at% Fe, respectively, and the solubility of Cr in (Fe, Cr)Ti were 9.0at% and 10.6at%.

      PubDate: 2017-06-07T03:28:43Z
  • Design of Laves-phase-packed spheres in wear-resistant Cu alloy by
           controlled liquid immiscibility
    • Abstract: Publication date: September 2017
      Source:Calphad, Volume 58
      Author(s): Kouji Tanaka, Hajime Kato, Tadashi Oshima
      The designed liquid immiscibility of Cu-Ni-Fe-Mo-Si alloy led to separation of the spherical second liquid in the Cu-rich liquid, which solidified into coarse hard grains packed with Laves phase. The coarseness of hard grains was controlled not only by the repulsive interactions in Cu–Fe and Cu–Mo system, but also the refining effect of Ni and Si. CALPHAD analysis of the multicomponent system confirmed the correlation of the calculated fraction of the separated liquid with the observed grain dimensions. It also provided a powerful prediction of the precipitates constituting the hard grains. Almost all of the alloying effects on the observed microstructures were successfully interpreted based on equilibrium immiscibility calculations, although a reason for the refining of spheres with increasing Si remains unclear.
      Graphical abstract image

      PubDate: 2017-05-27T12:33:54Z
  • Thermodynamic assessment of the Al-C-Fe system
    • Abstract: Publication date: September 2017
      Source:Calphad, Volume 58
      Author(s): Weisen Zheng, Shuang He, Malin Selleby, Yanlin He, Lin Li, Xiao-Gang Lu, John Ågren
      The Al-C-Fe system was assessed in the framework of the CALPHAD approach. Through the critical review of thermochemical properties of liquid Al-Fe alloys, the binary Al-Fe description was revised to agree better with the experimental data. The partitioning model based on the Compound Energy Formalism (CEF) was utilized to describe the disordered and ordered bcc, fcc and κ phases. Moreover, ab initio calculations were performed to determine the enthalpies of formation of the ordered structures based on the bcc and fcc lattices in the binary Al-Fe and for the end-members of the κ phase in the ternary Al-C-Fe system. In order to simplify the database, the present work also employed a two-sublattice model to describe the B2 ordered phase in the Al-Fe system, which can be applied easily to diffusion simulations. Comprehensive comparison between the model-predicted and experimental data confirms that the present evaluation describe the Al-C-Fe system satisfactorily, especially the κ phase.

      PubDate: 2017-05-18T11:47:04Z
  • Experimental and thermodynamic study of the Mg-Sn-Ca-Sr quaternary system:
           Part I-Mg-Sn-Ca ternary system
    • Abstract: Publication date: September 2017
      Source:Calphad, Volume 58
      Author(s): Jian Wang, Jiajian Han, Beining Du, Yixiong Huang, Liyuan Sheng, Weifeng Rao, Cuiping Wang, Xingjun Liu
      Four key samples of the Mg-Ca-Sn ternary system in the Mg-rich region at 415 and 350°C have been determined using the Scanning Electron Microscopy (SEM) equipped with Energy Dispersive X-Ray Spectrometry (EDS). The existence of the CaMgSn ternary compound was confirmed in these two isothermal sections. Thermodynamic optimizations of the Ca-Sn binary system and Mg-Ca-Sn ternary system were carried out using the CALPHAD (Calculation of Phase Diagrams) technique. The Modified Quasichemical Model (MQM) was used for the liquid solution which exhibits a high degree of short-range ordering behavior in the liquid solution. The solid phases are modeled with the Compound Energy Formalism (CEF). Finally, a self-consistent thermodynamic database of Mg-Ca-Sn ternary system has been constructed in the present work, which would provide an efficient and convenient way to study and develop the new Mg-Sn based alloys.

      PubDate: 2017-05-13T11:33:23Z
  • Thermodynamic modeling of the PbX (X=S,Te) phase diagram using a five
           sub-lattice and two sub-lattice model
    • Abstract: Publication date: September 2017
      Source:Calphad, Volume 58
      Author(s): M.C. Peters, Jeff.W. Doak, W.-W. Zhang, J.E. Saal, G.B. Olson, P.W. Voorhees
      Five-sublattice and two-sublattice models have been built to describe the PbX (X=S,Te) semiconductors using the CALPHAD method. The five-sublattice model has three additional sublattices to explicitly model interstitials, electrons, and holes. The experimental literature has been critically reviewed and many high temperature carrier concentration results used in previous assessments have been shown to be unreliable. First-principle calculations for the formation energies of neutral defects and their respective ionization energies have also been incorporated into the models. The models show an improvement over previous assessments of PbTe and are the first time PbS has not been treated as a stoichiometric compound in a CALPHAD assessment.

      PubDate: 2017-05-13T11:33:23Z
  • Au-Ni nanoparticles: Phase diagram prediction, synthesis,
           characterization, and thermal stability
    • Abstract: Publication date: September 2017
      Source:Calphad, Volume 58
      Author(s): J. Sopoušek, A. Kryštofová, M. Premović, O. Zobač, S. Polsterová, P. Brož, J. Buršík
      The Au-Ni nanoparticles (NPs) were prepared by oleylamine solvothermal synthesis from metal precursors. The Au-Ni phase diagram prediction respecting the particle size was calculated by the CALPHAD method. The hydrodynamic size of the AuNi NPs in a nonpolar organic solvent was measured by the dynamic light scattering (DLS) method. The average hydrodynamic sizes of the nanoparticle samples were between 18 and 25nm. The metallic composition of the AuNi NP samples was obtained by inductively-coupled plasma atomic emission spectroscopy (ICP-OES). The metallic fraction inside AuNi NPs was varied Au-(30–70)wt%Ni. The steric alkylamine stabilization was observed. The individual AuNi NPs were investigated by transmission electron microscopy (TEM). The dry nanopowder was also studied. The structures of the aggregated samples were investigated by scanning electron microscopy (SEM). The AuNi NPs reveal randomly mixed face-centered cubic (FCC) crystal lattices. The phase transformations were studied under inert gas and air. The samples were studied by differential scanning calorimetry (DSC).

      PubDate: 2017-05-13T11:33:23Z
  • Thermodynamic model for prediction of binary alloy nanoparticle phase
           diagram including size dependent surface tension effect
    • Abstract: Publication date: September 2017
      Source:Calphad, Volume 58
      Author(s): Fatemeh Monji, Mohammad Amin Jabbareh
      Considering the size effect of nanoparticles on surface tension, a new CALPHAD type thermodynamic model was developed to predict phase diagram of binary alloy nanoparticle systems. In contrast to conventional model, the new model can be applied to the nanoparticles smaller than the critical size (5NM in radius). For an example, the model applied to Ag – Au binary system and the results were compared with experimental data as well as conventional CALPHAD model and molecular dynamics simulation results.

      PubDate: 2017-05-02T10:41:32Z
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