| 1. |
- Bigdeli, Sedigheh, 1984, et al.
(författare)
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Strategies for High-Temperature Corrosion Simulations of Fe-Based Alloys Using the Calphad Approach : Part I
- 2021
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Ingår i: Journal of Phase Equilibria and Diffusion. - : Springer Nature. - 1547-7037 .- 1863-7345. ; 42:3, s. 403-418
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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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| 2. |
- Dyal Ukabhai, K., et al.
(författare)
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Formation of Ti2Cu in Ti-Cu Alloys
- 2022
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Ingår i: JOURNAL OF PHASE EQUILIBRIA AND DIFFUSION. - : Springer Nature. - 1547-7037 .- 1863-7345. ; 43:3, s. 332-344
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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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| 3. |
- He, Zhangting, et al.
(författare)
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A third generation Calphad description of Fe: revisions of fcc, hcp and liquid
- 2022
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Ingår i: Journal of Phase equilibria and Diffusion. - : Springer Science and Business Media LLC. - 1547-7037 .- 1863-7345.
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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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| 4. |
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| 5. |
- Lindwall, Greta, et al.
(författare)
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Development of a Diffusion Mobility Database for Co-Based Superalloys
- 2022
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Ingår i: Journal of Phase Equilibria and Diffusion. - : Springer. - 1547-7037 .- 1863-7345. ; 43:6, s. 931-952
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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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| 6. |
- Ågren, John, et al.
(författare)
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Simplified Growth Model for Multicomponent Systems : Inclusion of PARA and NPLE Conditions
- 2022
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Ingår i: Journal of Phase Equilibria and Diffusion. - : Springer Nature. - 1547-7037 .- 1863-7345. ; 43:6, s. 738-744
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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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| 7. |
- Ågren, John
(författare)
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The Onsager Reciprocity Relations Revisited
- 2022
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Ingår i: Journal of Phase Equilibria and Diffusion. - : Springer Nature. - 1547-7037 .- 1863-7345. ; 43:6, s. 640-647
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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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