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1.
  • Arvhult, Carl-Magnus, et al. (författare)
  • Experimental Phase Diagram Study of the Fe-Ni-Te System
  • 2019
  • Ingår i: JOURNAL OF PHASE EQUILIBRIA AND DIFFUSION. - : Springer Nature. - 1547-7037 .- 1863-7345. ; 40:4, s. 610-622
  • Tidskriftsartikel (refereegranskat)abstract
    • Fe-Ni-Te alloys have been experimentally studied using isothermal heat treatments with SEM-EDS and WDS, XRD, and DTA in order to add phase diagram data for a thermodynamic assessment. This is for the application of fission product-induced corrosion of the stainless steel cladding of nuclear fuel pins, where Te is a key element. Phase diagram data are presented at phase. SEM images show unidentified precipitates in several samples.
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2.
  • Bigdeli, Sedigheh, et al. (författare)
  • A New Description of Pure C in Developing the Third Generation of Calphad Databases
  • 2018
  • Ingår i: Journal of Phase Equilibria and Diffusion. - : Springer Nature. - 1547-7037 .- 1863-7345. ; 39:6, s. 832-840
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • In connection to developing the third generation of Calphad databases a new thermodynamic description is presented for unary carbon. Models used in this work have more physical basis and are valid down to 0 K. The anisotropy in graphite, caused by weak Van der Waals inter-plane forces makes it difficult to fit the heat capacity data by a single Einstein tempera-ture for modelling the harmonic vibration of the atoms. By using multiple Einstein temperatures this problem is solved and a good agreement with the experimental data at low temperatures is achieved. Diamond is mod-eled using new models too, and the two-state model is used for modelling the liquid phase.
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3.
  • Bigdeli, Sedigheh, 1984, et al. (författare)
  • Strategies for High-Temperature Corrosion Simulations of Fe-Based Alloys Using the Calphad Approach : Part I
  • 2021
  • Ingår i: Journal of Phase Equilibria and Diffusion. - : Springer Nature. - 1547-7037 .- 1863-7345. ; 42:3, s. 403-418
  • Tidskriftsartikel (refereegranskat)abstract
    • The environmental degradation of materials at high temperatures limits the useful life of different industrial components and hinders the development of more economical and environmentally friendly processes for the energy production. Despite the importance of this phenomena, a model to predict lifetime of materials that degrade due to high-temperature corrosion has up till now been lacking due to limitations of the computational possibilities and the complex nature of oxidation. In the present work we develop some strategies to model high-temperature corrosion in Fe-based alloys using the Calphad (Calculation of Phase Diagrams) approach. It is proposed that kinetic-based simulations for oxidation of Al and Cr can accurately represent the lifetime of the protective layers in FeCrAl and FeCr alloys at different temperatures in air. The oxide systems are in addition investigated by equilibrium calculations. The corrosion mechanisms of FeCr and FeCrAl alloys are discussed based on theoretical and experimental knowledge.
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4.
  • Chen, Qing, et al. (författare)
  • On Negative Diagonal Elements in the Diffusion Coefficient Matrix of Multicomponent Systems
  • 2018
  • Ingår i: JOURNAL OF PHASE EQUILIBRIA AND DIFFUSION. - : Springer. - 1547-7037 .- 1863-7345. ; 39:5, s. 592-596
  • Tidskriftsartikel (refereegranskat)abstract
    • In multicomponent systems the diffusion coefficient turns into a matrix. The diagonal elements represent diffusion of a species caused by its own concentration gradient. In a thermodynamically stable binary alloy it is easy to see that this diagonal element must be positive but in a multicomponent system it is less obvious. The sign of the diagonal elements in the general case is discussed in this report. It is shown that the sign of an individual diagonal element has no physical meaning but can be changed by changing the dependent concentration variable. Only the sum of all the diagonal elements need to be positive in a stable system.
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5.
  • Dilner, David, et al. (författare)
  • Thermodynamic Assessment of the Fe-Ca-S, Fe-Mg-O and Fe-Mg-S Systems
  • 2016
  • Ingår i: Journal of Phase Equilibria and Diffusion. - : Springer-Verlag New York. - 1547-7037 .- 1863-7345. ; , s. 1-16
  • Tidskriftsartikel (refereegranskat)abstract
    • Thermodynamic descriptions of the Fe-Mg-O, Fe-Ca-S and Fe-Mg-S systems are all important in order to perform thermodynamic calculations related to the steelmaking process. The experimental information of many sulphur-containing systems, including Fe-Ca-S and Fe-Mg-S, is lacking and they are here thus approximated to behave similarly to the corresponding oxygen systems. This study presents a description of the Fe-Mg-O system in good agreement with experimental information. Additionally, descriptions of the Fe-Ca-S and Fe-Mg-S systems are presented. These descriptions may be reasonable estimations considering the lack of experimental information.
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6.
  • Dyal Ukabhai, K., et al. (författare)
  • Formation of Ti2Cu in Ti-Cu Alloys
  • 2022
  • Ingår i: JOURNAL OF PHASE EQUILIBRIA AND DIFFUSION. - : Springer Nature. - 1547-7037 .- 1863-7345. ; 43:3, s. 332-344
  • Tidskriftsartikel (refereegranskat)abstract
    • One of the major issues with dental implants is failure due to bacterial infection, and additions of copper are known to improve the antimicrobial properties of Ti alloys. There are inconsistencies in the Ti rich area of the Cu-Ti binary phase diagram, hence the need to find out if Ti2Cu or Ti3Cu is formed, and to identify the type of formation of Ti2Cu. Four alloys: 20, 33, 40 and 50 Cu (mass%) were produced by arc melting and studied using SEM, XRD and DSC. The reactions were derived, and the temperatures of the reactions were determined by DSC. The formation of Ti2Cu is congruent, and no Ti3Cu was found.
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7.
  • He, Zhangting, et al. (författare)
  • A third generation Calphad description of Fe: revisions of fcc, hcp and liquid
  • 2022
  • Ingår i: Journal of Phase equilibria and Diffusion. - : Springer Science and Business Media LLC. - 1547-7037 .- 1863-7345.
  • Tidskriftsartikel (refereegranskat)abstract
    • The thermodynamic description of pure Fe was re-assessed using updated third generation Calphad models and taking into account the most recent theoretical data. In the present re-assessment, a critical evaluation was performed for the magnetic properties of the fcc and hcp phases yielding different descriptions from those accepted in the SGTE database. The selected magnetic properties enable us to model the thermodynamic properties of fcc satisfactorily without using the magnetic two-state model. A new method was applied to extrapolate the thermodynamic data for the solid phases, i.e. a single Gibbs energy expression is used for the entire temperature range for the bcc, fcc and hcp phases. The description of the liquid phase was re-evaluated following a recent suggestion on estimating the electronic heat capacity coefficient for the liquid phase. Overall, the present Calphad description can reproduce the selected experimental and theoretical data well.
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8.
  • Höglund, Lars, et al. (författare)
  • Simulation of Carbon Diffusion in Steel Driven by a Temperature Gradient
  • 2010
  • Ingår i: Journal of Phase Equilibria and Diffusion. - : Springer Science and Business Media LLC. - 1547-7037 .- 1863-7345. ; 31:3, s. 212-215
  • Tidskriftsartikel (refereegranskat)abstract
    • The basis of thermomigration in multicomponent alloys is summarized, and the general equations are given and implemented in the DICTRA software. Experimental information from Okafor et al. is analyzed with the new simulations and it is concluded that steady- state conditions was not established during their experiment. A heat of transport Q(C)* = -44000 J/mol, almost four times larger than the value given by Okafor et al., was found to give a satisfactory representation of the experimental information.
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9.
  • Kjellqvist, Lina, 1979-, et al. (författare)
  • Thermodynamic assessment of the Fe-Mn-O system
  • 2010
  • Ingår i: Journal of Phase Equilibria and Diffusion. - : Springer US. - 1547-7037 .- 1863-7345. ; 31:2, s. 113-134
  • Tidskriftsartikel (refereegranskat)abstract
    • The C-Cr-Fe-Ni-O system has recently been studied with the intention to thermodynamically describe the influence of oxygen on high alloyed steels. In this study the ternary Fe-Mn-O system is assessed and part of the binary Mn-O system is reassessed. α- and β-hausmannite (Mn3O4) were earlier described as stoichiometric phases, but are here described using the compound energy formalism with a four sublattice model to be consistent with the preceding study of the Cr-Fe-Ni-O spinel. The liquid phase is assessed using the ionic two-sublattice model. Good agreement between calculated and experimental values is achieved.
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10.
  • Li, Zhou, 1987-, et al. (författare)
  • Thermodynamic Modeling of Pure Co Accounting Two Magnetic States for the Fcc Phase
  • 2018
  • Ingår i: JOURNAL OF PHASE EQUILIBRIA AND DIFFUSION. - : Springer. - 1547-7037 .- 1863-7345. ; 39:5, s. 502-509
  • Tidskriftsartikel (refereegranskat)abstract
    • The thermodynamic functions of the pure Co were assessed using CALPAHD method for the third generation thermodynamic databases. To model the magnetic properties of the cobalt, a two-state magnetic model was accounted for the fcc phase. Calculated results were compared with the experimental information and a good fit to the experimental data was achieved.
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11.
  • Lindwall, Greta, et al. (författare)
  • Assessment and evaluation of mobilities for diffusion in the bcc Cr-Mo-Fe system
  • 2012
  • Ingår i: Journal of Phase Equilibria and Diffusion. - : ASM International. - 1547-7037 .- 1863-7345. ; 33:5, s. 375-389
  • Tidskriftsartikel (refereegranskat)abstract
    • An assessment of the diffusion mobility functions for diffusion in the bcc Cr-Fe-Mo system ispresented. The optimization of the mobility parameters is performed by utilizing experimentaldiffusion data available in literature. New diffusion data for the Mo diffusion is produced by adiffusion couple experiment and is accounted for in the optimization. Agreement between calculatedand measured diffusion coefficients is found. An M6C coarsening experiment is performedand the measured coarsening rate can be reproduced by diffusion calculation using the DICTRA software and the developed kinetic description. The mobility parameters are shown tohave a strong influence on the calculated coarsening rate.
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12.
  • Lindwall, Greta, 1981-, et al. (författare)
  • Assessment and evaluation of mobilities for diffusion in the bcc Cr-V-Fe system
  • 2009
  • Ingår i: Journal of phase equilibria and diffusion. - : ASM International. - 1547-7037 .- 1863-7345. ; 30:4, s. 323-333
  • Tidskriftsartikel (refereegranskat)abstract
    • Assessments of diffusion mobility parameters are performed for the bcc Cr-V-Fe alloy systemby taking available literature data into account. The main focus is on the diffusion of V in thebcc phase where, in addition to all binaries, ternary interaction parameters are assessed. Anexperiment is performed in order to study the coarsening of V-rich MC carbide, where thediffusion of V is believed to be of major importance. The measured coarsening rate is comparedwith the rate calculated using DICTRA, and found to be in satisfactory agreement. Theaspects of coarsening experiments as a method to evaluate diffusion mobility data arediscussed.
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13.
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14.
  • Lindwall, Greta, et al. (författare)
  • Development of a Diffusion Mobility Database for Co-Based Superalloys
  • 2022
  • Ingår i: Journal of Phase Equilibria and Diffusion. - : Springer. - 1547-7037 .- 1863-7345. ; 43:6, s. 931-952
  • Tidskriftsartikel (refereegranskat)abstract
    • To facilitate the development of high-temperature Co-based γ-γ′ superalloys, a Co-Ni based diffusion mobility database is developed for the eight component FCC (Face Centered Cubic) system of Co-Al-W-Ni-Cr-Ti-Ta-Re. A CALPHAD approach is used to represent the temperature and composition dependency of the multicomponent system. The mobility descriptions were based on previous assessment work for the Ni-based superalloys, published experimental and computational data, and established diffusion correlations. The initial mobility descriptions were then refined using additional diffusion couple experimental data, particularly for the Co-Cr, Co-Ta, and Ni-Ta systems. After re-optimizing the descriptions with the new experimental data, the mobility descriptions were validated using a collection of published diffusion couple composition profiles, which were not included in the initial assessment process.
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15.
  • Lindwall, Greta, et al. (författare)
  • Diffusion in the Ti-Al-V System
  • 2018
  • Ingår i: JOURNAL OF PHASE EQUILIBRIA AND DIFFUSION. - : Springer. - 1547-7037 .- 1863-7345. ; 39:5, s. 731-746
  • Tidskriftsartikel (refereegranskat)abstract
    • Diffusion in the Ti-Al-V system is studied and a CALculation of Phase Diagrams (CALPHAD) diffusion mobility description is developed. Diffusion couple experiments are performed to obtain diffusion paths in the hcp phase at 923 K, 1023 K and 1123 K. The diffusion coefficient of V in the hcp-Ti phase is found to decrease with increasing Al alloying. A forward-simulation analysis is used to evaluate the impurity diffusion coefficient for Al and V diffusion in the hcp Ti-V and the Ti-Al systems which are used as input in the mobility modeling. The composition dependency for the diffusion in the hcp phase in the ternary system is accounted for and a CALPHAD diffusion mobility description is obtained by directly optimizing the mobility parameters as a function of the experimental composition profiles from the diffusion couples. Both experimental data and previous diffusion mobility descriptions in the literature for the bcc Ti-Al-V phase are adopted. A complete description of diffusion in both the hcp and bcc phases for the Ti-Al-V system is presented with the aim to be used for design of Ti alloys and processes.
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16.
  • Magnusson, Hans, et al. (författare)
  • Diffusion, Permeation and Solubility of Hydrogen in Copper
  • 2017
  • Ingår i: Journal of Phase Equilibria and Diffusion. - : Springer Science and Business Media LLC. - 1547-7037 .- 1863-7345. ; 38:1, s. 65-69
  • Tidskriftsartikel (refereegranskat)abstract
    • The thermodynamic description for the Cu-H system has been updated. The solubility of hydrogen in copper at low temperature has been backwards calculated from permeability data. The solubility, diffusivity, and permeability of hydrogen in copper can be described by single Arrhenius expressions. These expressions are given below. The temperature dependence of both solubility and diffusivity will together yield a strong temperature dependency on the permeability. The possibility for hydrogen transport in copper is therefore limited at low temperature. (Formula Presented).
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17.
  • Mao, Huahai, 1971-, et al. (författare)
  • TCHEA1 : A Thermodynamic Database Not Limited for "High Entropy'' Alloys
  • 2017
  • Ingår i: Journal of Phase Equilibria and Diffusion. - : Springer. - 1547-7037 .- 1863-7345. ; 38:4, s. 353-368
  • Tidskriftsartikel (refereegranskat)abstract
    • In this paper we report a thermodynamic database which was developed by using the CALPHAD approach. The TCHEA1 database includes 15 chemical elements (Al, Co, Cr, Cu, Fe, Hf, Mn, Mo, Nb, Ni, Ta, Ti, V, W and Zr). It is suitable for the study of Bcc and Fcc HEA systems. The database is constructed based on the thermodynamic assessment of all binary systems and many key ternary systems where almost all possible metastable and stable phases are considered. It is extensively demonstrated in the present work that TCHEA1 gives satisfactory prediction on the phase equilibria in various HEA systems (quaternary to ennead) and wide temperature ranges (liquidus to subsolidus). Thermodynamic stability calculations of simple solid solutions (Bcc and Fcc) and intermetallics (sigma, Laves, l-phase etc.) are validated against the available experimental information in as-cast or as-annealed state. Such CALPHAD database focusing on the modelling of Gibbs energy rather than entropy makes reliable predictions of thermodynamic equilibrium and phase transformation, no matter whether the alloy/system has high entropy or not. Cases with miscibility gap in liquid and solid solutions and second-order phase transition at low temperatures are demonstrated. With the volume data included, TCHEA1 is capable to predict the density and thermal expansion coefficient of HEAs as well. This thermodynamic database is also applicable in process simulations when used together with compatible kinetic databases.
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18.
  • Omori, Toshihiro, et al. (författare)
  • A Generalized Approach Obeying the Third Law of Thermodynamics for the Expression of Lattice Stability and Compound Energy : A Case Study of Unary Aluminum
  • 2018
  • Ingår i: JOURNAL OF PHASE EQUILIBRIA AND DIFFUSION. - : Springer. - 1547-7037 .- 1863-7345. ; 39:5, s. 519-531
  • Tidskriftsartikel (refereegranskat)abstract
    • Recently, Hillert and Selleby proposed a simple method for expression of the lattice stability or Gibbs energy of formation that does not violate the third law of thermodynamics. This method describes the derivation of the Gibbs energy function from high temperatures down to 0 K by interpolation, instead of extrapolation from room temperature to 0 K. In the present work, their original method is discussed in terms of determination of the characteristic parameter values. Keeping the essential interpolation character of their method, a generalized approach is presented for expressing the lattice stability through parameter optimizations. This approach retains the zero point entropy of substances and is in line with the development of the third generation CALPHAD databases. Using the Al unary system as a case study, the lattice stabilities of the hcp and bcc phases are investigated. The respective Einstein temperatures are also evaluated. At high temperatures, the present descriptions reproduce the lattice stabilities suggested by SGTE for the existing second generation of databases, with a reasonable accuracy. More importantly, information from ab initio calculations (total energy at 0 K) is also used for this optimization and the present method results in a physically sounder description of thermodynamic properties at lower temperatures down to 0 K. The present approach provides a simple and flexible way to estimate the lattice stabilities, with potential applicability for the Gibbs energy of formation of stoichiometric compounds and the excess energy of solution phases, in accordance with the third law of thermodynamics.
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19.
  • von Fieandt, Linus, et al. (författare)
  • Chemical Interactions Between Cemented Carbide and Difficult-to-Machine Materials by Diffusion Couple Method and Simulations
  • 2018
  • Ingår i: Journal of phase equilibria and diffusion. - : SPRINGER. - 1863-7345 .- 1547-7037. ; 39:4, s. 369-376
  • Tidskriftsartikel (refereegranskat)abstract
    • A simple and efficient diffusion couple method is utilized to study the chemical interactions between cemented carbide cutting tools and difficult-to-machine materials (Ti, Ti-6Al-4V, Ni, Inconel 718, Fe, and AISI 316L). The experimental results and simulations probe different chemical interactions between the cemented carbide and work materials. In particular, the formation of a thick TiC layer is observed at the cemented carbide/Ti and Ti-6Al-4V interface while eta-phase is formed at the interface between the cemented carbide and work materials Inconel 718, Fe and AISI 316L. Pure titanium and Ti-6Al-4V both interact strongly with the tool causing formation of TiC and dissolution of WC-grains. Experiments and diffusion simulations confirm bcc-W formation and progressive diffusion of W into bcc-Ti. For both Ti and Fe work materials a dense band of carbides (WC + eta or WC + TiC) forms at the interface, effectively inhibiting further diffusion. Ni does not form any stable carbide and lowers the eta-phase limit in terms of carbon content, wherefore diffusion can occur freely. The diffusion couple method used in this work, corroborated by DICTRA simulations should serve as a useful tool in the detailed analysis of worn tools where chemical wear is dominant.
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20.
  • Zhang, Rui, et al. (författare)
  • Prediction of Martensite Start Temperature for Lightweight Fe-Mn-Al-C Steels
  • 2018
  • Ingår i: JOURNAL OF PHASE EQUILIBRIA AND DIFFUSION. - : Springer. - 1547-7037 .- 1863-7345. ; 39:5, s. 476-489
  • Tidskriftsartikel (refereegranskat)abstract
    • A tailor-made thermodynamic database of the Fe-Mn-Al-C system was developed using the CALPHAD approach. The database enables predicting phase equilibria and thereby assessing the resulting microstructures of Fe-Mn-Al-C alloys. Available information on the martensite start (M-s ) temperature was reviewed. By employing the M-s property model in the Thermo-Calc software together with the new thermodynamic database and experimental M-s temperatures, a set of model parameters for the Fe-Mn-Al-C system in the M-s model was optimised. Employing the newly evaluated parameters, the calculated M-s temperatures of the alloys in the Fe-Mn-Al-C system were compared with the available measured M-s temperatures. Predictions of M-s temperatures were performed for the alloys, Fe-10, 15 and 20 wt.% Mn-xAl-yC. The predictability of the M-s model can be further validated when new experimental M-s temperatures of the Fe-Mn-Al-C system are available.
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21.
  • Zhang, Wei-Wei, et al. (författare)
  • Thermodynamic Assessment of the Cu-B System Supported by Key Experiment and First-Principles Calculations
  • 2009
  • Ingår i: Journal of Phase Equilibria and Diffusion. - : Springer Science and Business Media LLC. - 1547-7037 .- 1863-7345. ; 30:5, s. 480-486
  • Tidskriftsartikel (refereegranskat)abstract
    • The Cu-B system was investigated via a hybrid approach of key experiment and thermodynamic modeling. Based on the critically assessed Cu-B phase diagram, seven crucial alloys were selected and prepared by arc melting the pure elements. An inductively coupled plasma-atomic emission spectrometric analysis was conducted to determine the compositions of the prepared alloys. The phase equilibria were determined by using x-ray diffraction, electron probe microanalysis, and differential thermal analysis. The temperature associated with the eutectic reaction, L double left right arrow (B) + (Cu); was measured to be 1028 +/- 2 degrees C. First-principles calculations indicate that the energy of inserting a B atom into the interstitial vacancy (Va) site of the lattice for Cu atoms is marginally lower than that of substituting for a Cu atom with a B atom. Consequently, the sublattice model (Cu)(B, Va) in which B atoms occupy the interstitial sites was employed for the fcc (Cu) phase rather than the model (Cu, B)(Va) in which B atoms substitute for Cu atoms. A thermodynamic modeling of the Cu-B system was then performed by considering the reliable literature data and the present experimental results. A good agreement between modeling and experiment was obtained.
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22.
  • Zheng, Weisen, et al. (författare)
  • Thermodynamic Evaluation of the Co-Al-C System by Coupling Ab Initio Calculations and CALPHAD Approach
  • 2018
  • Ingår i: JOURNAL OF PHASE EQUILIBRIA AND DIFFUSION. - : Springer. - 1547-7037 .- 1863-7345. ; 39:5, s. 538-548
  • Tidskriftsartikel (refereegranskat)abstract
    • The ternary Co-Al-C system was thermodynamically assessed using the CALPHAD method based on the critical review of all experimental information in the system. The kappa-carbide was described with a three-sublattice model (Al,Co)(3)(Al,Co)(1)(C,Va)(1). To support the assessment, the enthalpies of formation of all end-members of the kappa-carbide were studied by ab initio calculations. The solubility ranges of the carbon in the kappa-carbide, the alpha Co and the AlCo (B2) phases were well reproduced. The equilibria involving the liquid phase were reasonably described using the present set of thermodynamic parameters.
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23.
  • Ågren, John, et al. (författare)
  • Simplified Growth Model for Multicomponent Systems : Inclusion of PARA and NPLE Conditions
  • 2022
  • Ingår i: Journal of Phase Equilibria and Diffusion. - : Springer Nature. - 1547-7037 .- 1863-7345. ; 43:6, s. 738-744
  • Tidskriftsartikel (refereegranskat)abstract
    • A simplified model for the growth of particles in a multicomponent system has been developed. The model takes into account of the effects of cross diffusion and finite interface mobility. It can be applied in a straightforward way to treat precipitation under the conditions of paraequilibrium (PARA) or non-partitioning local equilibrium (NPLE). 
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24.
  • Ågren, John (författare)
  • The Onsager Reciprocity Relations Revisited
  • 2022
  • Ingår i: Journal of Phase Equilibria and Diffusion. - : Springer Nature. - 1547-7037 .- 1863-7345. ; 43:6, s. 640-647
  • Tidskriftsartikel (refereegranskat)abstract
    • The Onsager relations are discussed and it is suggested that they should be interpreted as there is a frame of reference where all the transport processes are independent. The concepts are illustrated with isobarothermal diffusion in simple metallic phases as well as complex ionic systems. A transformation from lattice-fixed frame of reference to number-fixed frame gives the Kirkendall effect as a cross effect. 
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25.
  • Abe, T., et al. (författare)
  • Thermodynamic assessment of the Cu-Pt system
  • 2006
  • Ingår i: Journal of Phase Equilibria and Diffusion. - 1547-7037. ; 27:1, s. 5-13
  • Tidskriftsartikel (refereegranskat)abstract
    • A CALPHAD assessment of the Cu-Pt system has been carried out. Two and four sublattice models were applied to describe the Gibbs free energies of ordered phases where the contribution of SRO is taken explicitly into account through the reciprocal parameters. The disordered fcc A1 and liquid phases were treated as substitutional solutions. A consistent set of parameters for the phases in the Cu-Pt system as obtained, and those parameters can satisfactorily reproduce the experimental phase equilibria and thermodynamic properties, such as enthalpies, activity of Cu, and long-range order parameters.
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26.
  • Borgenstam, Annika, et al. (författare)
  • DICTRA, a tool for simulation of diffusional transformations in alloys
  • 2000
  • Ingår i: Journal of phase equilibria (Print). - : Springer Science and Business Media LLC. - 1054-9714 .- 1544-1032 .- 1863-7345. ; 21:3, s. 269-280
  • Tidskriftsartikel (refereegranskat)abstract
    • In the present paper, a general survey of the diffusion-controlled transformations (DICTRA) software is given. DICTRA is an engineering tool for diffusion simulations in multicomponent alloys. The simulations are based on multicomponent diffusion and thermodynamic data, both obtained by analyzing and assessing experimental information. This allows for many different cases to be studied as soon as the underlying data are available. DICTRA is not a complete simulation tool because only geometries that can be transformed into one space variable can be treated, but many well posed problems of practical interest may be solved. The program contains several different models, which are discussed in the present paper. Each model has its own applications and several examples from recent simulations are given in order to demonstrate the usage of the particular models.
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27.
  • Borggren, U., et al. (författare)
  • A thermodynamic database for special brass
  • 2003
  • Ingår i: Journal of phase equilibria (Print). - : Springer Science and Business Media LLC. - 1054-9714 .- 1544-1032 .- 1863-7345. ; 24:2, s. 110-121
  • Tidskriftsartikel (refereegranskat)abstract
    • In the present work a thermodynamic database for brass alloys is developed. The database may be used to calculate phase diagrams and property diagrams and to simulate solidification, calculations that may be used to develop new alloys and to increase the understanding of existing ones. When developed, such a database reduces the need for further experimental investigations considerably. The present work is focused on so-called special brass (i.e., alloys of Cu and Zn with small additions of, for instance, Al, As, B, Fe, Pb, and/or Si). The database was created using available thermodynamic descriptions and unavailable systems were assessed using the CALPHAD technique. Experimental information was taken from literature and from experimental results obtained in the present work. The database contains the elements Al, Cu, Pb, Si, and Zn. Calculated phase diagrams show that the peritectic reaction in the Cu-Zn system is very sensitive to small additions of Al and Si, which moves the peritectic reaction towards lower Zn contents and higher temperatures.
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28.
  • Bratberg, Johan, et al. (författare)
  • A thermodynamic assessment of the Co-V system
  • 2003
  • Ingår i: Journal of phase equilibria (Print). - : Springer Science and Business Media LLC. - 1054-9714 .- 1544-1032 .- 1863-7345. ; 24:6, s. 495-503
  • Tidskriftsartikel (refereegranskat)abstract
    • A thermodynamic evaluation of the binary Co-V system has been done using experimental thermochemical and phase diagram data. A consistent thermodynamic description, using a Redlich-Kister model for solution phases and sublattice models for the intermetallics, was obtained, and it agreed well with the critically evaluated experimental data. The model for the solid phases accounts for the magnetic contribution to the Gibbs energy. The addition of a composition dependent magnetic term also led to the prediction of an fcc-Co miscibility gap. The model parameters have been determined using a computerized optimization technique. Several diagrams and tables concerning phase equilibria are presented.
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29.
  • Hallström, Samuel (författare)
  • Thermodynamic assessment of the Ni-Ru system
  • 2004
  • Ingår i: Journal of phase equilibria (Print). - : Springer Science and Business Media LLC. - 1054-9714 .- 1544-1032 .- 1547-7037 .- 0000-0000. ; 25:3, s. 252-254
  • Tidskriftsartikel (refereegranskat)abstract
    • The Ni-Ru system is assessed using the CALPHAD technique. The only available experimental information for this system concerns phase equilibria, whereas no thermochemical information has been found. The THERMO-CALC software is applied to obtain Gibbs energy (G) functions for the individual phases. The phase diagram calculated from the new G functions is in excellent agreement with the experimental diagram, and all the thermodynamic parameters are given in the Appendix. In addition, tentative activity diagrams and the metastable miscibility gaps in fcc and hcp phases are calculated from the new thermodynamic description.
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30.
  • Markström, Andreas, 1975-, et al. (författare)
  • A revised thermodynamic description of the Co-W-C system
  • 2005
  • Ingår i: Journal of Phase Equilibria and Diffusion. - : Springer Science and Business Media LLC. - 1547-7037 .- 0000-0000. ; 26:2, s. 152-160
  • Tidskriftsartikel (refereegranskat)abstract
    •  A thermodynamic reassessment of the Co-W-C system is presented. New information on the liquid (L)+face-centered cubic (fcc)+graphite+WC and L+fcc+WC+M6C equilibria has recently been published. Because these equilibria are very important for extrapolation to higher-order systems, the ternary system has been revised. A revision of the Co-W system also has been performed.
  •  
31.
  • Tang, W. J., et al. (författare)
  • Phase equilibria in the pseudobinary Ti0.5Ni0.5-Ti0.5Cu0.5 system
  • 2000
  • Ingår i: Journal of phase equilibria (Print). - : Springer Science and Business Media LLC. - 1054-9714 .- 1544-1032 .- 1863-7345. ; 21:3, s. 227-234
  • Tidskriftsartikel (refereegranskat)abstract
    • The pseudobinary Ti0.5Ni0.5-Ti0.5Cu0.5 system was analyzed using thermodynamic models for the Gibbs energy of individual phases in the system. The TiNi intermetallic phase crystallizes with the B2 CsCl-type structure and is an ordered form of the A2 BCC structure, It was treated with a two-sublattice model (Cu, Ni, Ti, Va)(0.5)(Cu, Ni, Ti, Va)(0.5), where Va represents a vacancy and one sublattice is occupied predominantly by Ti and the other by Ni and Cu. Other phases such as B11 based on a TiCu compound and low-temperature phases B19' and B19 were also described with two-sublattice models with different distribution of atoms on each sublattice, A thermodynamic description of the Ti0.5Ni0.5-Ti0.5Cu0.5 system was obtained from an optimization based on experimental information. The calculated diagram of the pseudobinary Ti0.5Ni0.5-Ti0.5Cu0.5 system at high temperatures exhibits eutectic solidification of liquid and shows satisfactory agreement with experimental data. The phase relations among the B2, B19', and B19 phases at low temperatures mere also assessed on the basis of experimental information from martensitic transformations.
  •  
32.
  • Thorning, Casper, et al. (författare)
  • The Role of Grain Boundary Diffusion in Initial Selective Oxidation Kinetics of a Manganese-Aluminum TRIP Steel
  • 2005
  • Ingår i: Journal of Phase Equilibria and Diffusion. - 1547-7037. ; 26:5, s. 539-546
  • Tidskriftsartikel (refereegranskat)abstract
    • Confocal scanning laser microscopy (CSLM) was used in real-time observation of alloy element oxidation of a manganese/aluminum transformation induced plasticity (TRIP) steel. CSLM images reveal a marked role of grain boundaries in the overall initial oxidation kinetics of the alloy and consequently in the morphology of the initial surface oxide. Changing the grain size and the oxidation temperature results in a change in the overall kinetics of selective oxidation and in the importance of oxidation at grain boundaries, respectively. Electron backscattered diffraction mapping was used to characterize the grain boundaries intersecting the surface over an area of the alloy. Subsequent CSLM observation of selective oxidation over the same area allowed quantification of oxidation kinetics as a function of individual grain boundary misorientation.
  •  
33.
  • Toffolon, C., et al. (författare)
  • Reassessment of the Nb-Sn system
  • 2002
  • Ingår i: Journal of phase equilibria (Print). - : Springer Science and Business Media LLC. - 1054-9714 .- 1544-1032 .- 1863-7345. ; 23:2, s. 134-139
  • Tidskriftsartikel (refereegranskat)abstract
    • A new assessment of the Nb-Sn system is proposed considering the Nb3Sn phase stable down below room temperature. The Gibbs energy of formation of the solution and compound phases in the Nb-Sn system were derived from an optimization procedure using all the available experimental thermodynamic and phase diagram data. In particular, the enthalpy of formation of the Nb3Sn phase at 1350 degreesC was determined experimentally in this study. The thermodynamic description of the intermetallic compounds was made using a sublattice model, while a Redlish-Kister polynomial was used for the solution phases.
  •  
34.
  • Tolochko, O., et al. (författare)
  • Thermodynamic properties of supercooled Fe-B liquids - A theoretical and experimental study
  • 2000
  • Ingår i: Journal of phase equilibria (Print). - : Springer Science and Business Media LLC. - 1054-9714 .- 1544-1032 .- 1863-7345. ; 21:1, s. 19-24
  • Tidskriftsartikel (refereegranskat)abstract
    • The two-level model, recommended at the Ringberg 95 workshop, is applied to extrapolate the thermodynamic properties of liquid Fe-B alloys to large undercooling and to analyze the crystallization of glassy Fe85B15 alloys obtained by melt spinning. The new method yields practically the same phase diagram as the SGTE database but a superior result when evaluating the heat capacity, entropy, and crystallization heat at large undercooling. These properties are compared in the low-temperature range (700 to 800 K) with the experimental data obtained for an Fe85B15 metallic glass by scanning calorimetry. A good agreement between experiments and calculations is obtained when the observed magnetic transition at 530 K is taken into account.
  •  
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