| 1. |
- Alvares, E. D., et al.
(författare)
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An assessment of Fe-Nb-B melts using the two-state liquid model
- 2020
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Ingår i: Calphad. - : Elsevier Ltd. - 0364-5916 .- 1873-2984. ; 68
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Tidskriftsartikel (refereegranskat)abstract
- Amorphous alloys of the (Fe-Co-Ni)-(Cr-Mo-Nb)-B system are promising materials to supply the demands for higher wear resistance components in the petrochemical industry. Since the development of the CALPHAD method, the development of new metallic alloys has been accompanied by thermodynamic modelling and calculations. The prediction of the formation of amorphous alloys requires special care with the modeling of the liquid and or an amorphous phase. As a initial stage in the more complex system, the basic Fe-Nb-B ternary system was selected. In order to predict the stability and tendencies of transformations of these amorphous alloys, the Fe-Nb-B system was reassessed using Ågren's two-state model to describe the liquid phase. The results of the present assessment show very good agreement with the recently reported stable phase diagram. Furthermore, the use of the two-state model for the liquid is more accurate and physically consistent when evaluating transformations from supercooled liquid, as shown it the present work.
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| 2. |
- Edman Ansell, John, 1976-
(författare)
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Maktens tal och talets makt : Kunglig maktlegitimering i Erik XIV:s och Johan III:s tid
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis examines how Erik XIV and Johan III of Sweden used ethos construction and rhetoric to legitimize the new strong royal power during their combined reign from 1561 to 1592. The study analyses three different crises of legitimacy to understand how the kings and their allies negotiated these challenges and how the various strategies used by the rulers affected their ability to expand the space of legitimate royal power. The three crises are the dynastic crisis, the crisis of church politics, and the foreign policy crisis. The source material used includes written speeches, official letters from the kings, instructions for negotiators, and sermons. A key argument of the study is that the art of rhetoric is central to understanding the political conflicts of this era, and that, furthermore, 16th-century Swedish political culture should be analyzed as a part of the European Renaissance. The historical period is framed as a transitional political phase between an older political culture where legitimacy often came from sources connected to personal relationships and a new political culture where stable institutions fill that function. The results show that the Swedish kings shaped their royal ethos very differently, mainly depending on Erik's position as a hereditary ruler with initially strong legitimacy and Johan's much more precarious position as the usurper of Erik's throne. Erik, therefore, based his ethos on sources of legitimacy more connected to institutional tropes and was subsequently criticized for his inability to form and retain virtuous relationships. As an effect, Johan's ethos had to be the opposite. Since both relational and institutional sources of legitimacy were available, it was valuable to control the rhetorical arena of political negotiation. Political adversaries often switched positions between them as it fitted their argument. Historians have often misconstrued this as signs of irrationality or even mental illness. Instead, the study argues that it should be interpreted as careful positioning by rulers sensitive to the effects and benefits of ethos construction. Therefore, the main conclusion of this thesis is that the politics of rulers steeped in the political culture of the renaissance must be analyzed through the filter of rhetoric.
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| 3. |
- Haglund, Sven, et al.
(författare)
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Sintering of WC-Co Under Axial Load
- 2021
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Ingår i: International Journal of Materials Research - Zeitschrift für Metallkunde. - : WALTER DE GRUYTER GMBH. - 1862-5282 .- 2195-8556. ; 89:5, s. 323-326
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Tidskriftsartikel (refereegranskat)abstract
- Solid state sintering of cemented carbides is studied experimentally by means of dilatometry. Both an ordinary dilatometer and a dilatometer where an axial load was applied on the specimen were used. It is concluded that increased axial load, due to its hydrostatic component, gives larger volumetric shrinkage and that the decrease in the shrinkage rate at isothermal treatment is a result of a rapidly increasing rigidity of the powder compact at isothermal temperatures.
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| 4. |
- Haglund, Sven, et al.
(författare)
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Solid State Sintering of Cemented Carbides - An Experimental Study
- 2021
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Ingår i: International Journal of Materials Research - Zeitschrift für Metallkunde. - : WALTER DE GRUYTER GMBH. - 1862-5282 .- 2195-8556. ; 89:5, s. 316-322
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Tidskriftsartikel (refereegranskat)abstract
- Solid state sintering of cemented carbides is studied experimentally by means of dilatometry and SEM. Surface analysis of the powders is performed by means of ESCA, Auger and SIMS. It is concluded that for pure WC-Co mixtures the major part of densification occurs in the solid state and that high heating rates yield higher densification rates. 200 ppm of Ti, preferentially located at grain surfaces, yield a drastic decrease in sintering rate. Melting of the binder, i. e. transition to liquid phase sintering, only has a minor effect on densification rate.
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| 5. |
- Ideböhn, Veronica, 1992, et al.
(författare)
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Symmetry breaking in core-valence double ionisation of allene
- 2023
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Ingår i: Communications Chemistry. - : Springer Nature. - 2399-3669. ; 6:1
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Tidskriftsartikel (refereegranskat)abstract
- Allene serves as a model to study multiple ionization of organic molecules. Here, the authors use synchrotron radiation-based multi-particle coincidence techniques and high-level ab initio calculations to propose a simple physical model to elucidate the symmetry breaking in core-valence double ionization of allene. Conventional electron spectroscopy is an established one-electron-at-the-time method for revealing the electronic structure and dynamics of either valence or inner shell ionized systems. By combining an electron-electron coincidence technique with the use of soft X-radiation we have measured a double ionisation spectrum of the allene molecule in which one electron is removed from a C1s core orbital and one from a valence orbital, well beyond Siegbahns Electron-Spectroscopy-for-Chemical-Analysis method. This core-valence double ionisation spectrum shows the effect of symmetry breaking in an extraordinary way, when the core electron is ejected from one of the two outer carbon atoms. To explain the spectrum we present a new theoretical approach combining the benefits of a full self-consistent field approach with those of perturbation methods and multi-configurational techniques, thus establishing a powerful tool to reveal molecular orbital symmetry breaking on such an organic molecule, going beyond Lowdins standard definition of electron correlation.
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| 6. |
- Koulentianos, Dimitris, 1987, et al.
(författare)
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Formation and relaxation of K-2 and K-2V double-core-hole states in n-butane
- 2022
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 157:4
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Tidskriftsartikel (refereegranskat)abstract
- Using a magnetic bottle multi-electron time-of-flight spectrometer in combination with synchrotron radiation, double-core-hole pre-edge and continuum states involving the K-shell of the carbon atoms in n-butane ( n-C4H10) have been identified, where the ejected core electron(s) and the emitted Auger electrons from the decay of such states have been detected in coincidence. An assignment of the main observed spectral features is based on the results of multi-configurational self-consistent field (MCSCF) calculations for the excitation energies and static exchange (STEX) calculations for energies and intensities. MCSCF results have been analyzed in terms of static and dynamic electron relaxation as well as electron correlation contributions to double-core-hole state ionization potentials. The analysis of applicability of the STEX method, which implements the one-particle picture toward the complete basis set limit, is motivated by the fact that it scales well toward large species. We find that combining the MCSCF and STEX techniques is a viable approach to analyze double-core-hole spectra.
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| 7. |
- Lee, Gwonjin, et al.
(författare)
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A large-effect fitness trade-off across environments is explained by a single mutation affecting cold acclimation
- 2024
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences (PNAS). - 0027-8424 .- 1091-6490. ; 121:6
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Tidskriftsartikel (refereegranskat)abstract
- Identifying the genetic basis of local adaptation and fitness trade-offs across environments is a central goal of evolutionary biology. Cold acclimation is an adaptive plastic response for surviving seasonal freezing, and costs of acclimation may be a general mechanism for fitness trade-offs across environments in temperate zone species. Starting with locally adapted ecotypes of Arabidopsis thaliana from Italy and Sweden, we examined the fitness consequences of a naturally occurring functional polymorphism in CBF2. This gene encodes a transcription factor that is a major regulator of cold-acclimated freezing tolerance and resides within a locus responsible for a genetic trade-off for long-term mean fitness. We estimated the consequences of alternate genotypes of CBF2 on 5-y mean fitness and fitness components at the native field sites by comparing near-isogenic lines with alternate genotypes of CBF2 to their genetic background ecotypes. The effects of CBF2 were validated at the nucleotide level using gene-edited lines in the native genetic backgrounds grown in simulated parental environments. The foreign CBF2 genotype in the local genetic background reduced long-term mean fitness in Sweden by more than 10%, primarily via effects on survival. In Italy, fitness was reduced by more than 20%, primarily via effects on fecundity. At both sites, the effects were temporally variable and much stronger in some years. The gene-edited lines confirmed that CBF2 encodes the causal variant underlying this genetic trade-off. Additionally, we demonstrated a substantial fitness cost of cold acclimation, which has broad implications for potential maladaptive responses to climate change.
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| 8. |
- Li, Changle, 1992-, et al.
(författare)
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Critical assessment of Co-Cu phase diagram from first-principles calculations
- 2020
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Ingår i: Physical Review B. - : American Physical Society (APS). - 2469-9950 .- 2469-9969. ; 102:18
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Tidskriftsartikel (refereegranskat)abstract
- Using first-principles alloy theory, we perform a systematic study of the Co-Cu phase diagram. Calculations are carried out for ferromagnetic and paramagnetic Co1-xCux solid solutions with face-centered-cubic (fcc) crystal structure. We find that the equilibrium volumes and magnetic states are crucial for a quantitative description of the thermodynamics of the Co-Cu system at temperatures up to 1400 K. In particular, the paramagnetic state of Cu-rich alloys with persisting local magnetic moments is shown to be responsible for the solubility of a small amount of Co in fcc Cu whereas the excess entropy in the ferromagnetic Co-rich region critically depends on the adopted lattice parameters. None of the common local or semilocal density functional theory approximations have the necessary accuracy for the lattice parameters when compared to the experimental data. The predicted ab initio Co-Cu phase diagram is in good agreement with the measurements and CALPHAD data, making it possible to gain a deep insight into the various contributions to the Gibbs free energy. The present study provides an atomic-level description of the thermodynamic quantities controlling the limited mutual solubility of Co and Cu and highlights the importance of high-temperature magnetism.
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| 9. |
- Linder, David, et al.
(författare)
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Indentation behavior of highly confined elasto-plastic materials
- 2020
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Ingår i: International Journal of Solids and Structures. - : Elsevier. - 0020-7683 .- 1879-2146. ; 193-194, s. 69-78
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Tidskriftsartikel (refereegranskat)abstract
- The effect of geometric confinement is well-known from hardness measurements of thin films on stiff substrates and has been modeled both phenomenologically and using e.g. Finite Element Analysis. However, these models are mainly focused on a specific experiment or a certain material family. In the present work, Finite Element Analysis is used to gain a better understanding of the interplay between geometric constraints in various microstructures and a wide range of materials properties. It is shown that a very simple model can be used to replicate thin film hardness data where the film is softer than the substrate as well as how materials properties alter the indentation behavior of materials confined in one to three dimensions. It is shown that qualitative agreement with nanoindentation of the metallic binder phase in the complex 3D-microstructure of a cemented carbide is achieved using an axisymmetric “pill-box” model with classical plasticity. It is also shown that the effect of higher-order confinement can be described by the Korsunsky thin film hardness model by re-optimizing the fitting parameters.
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| 10. |
- Linder, David, et al.
(författare)
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Modeling confined ductile fracture - A void-growth and coalescence approach
- 2020
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Ingår i: International Journal of Solids and Structures. - : Elsevier BV. - 0020-7683 .- 1879-2146. ; 202, s. 454-462
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Tidskriftsartikel (refereegranskat)abstract
- In a composite material a soft, ductile matrix can be confined by a hard, brittle phase, altering its deformation and fracture behavior. Increasing confinement leads to embrittlement of the matrix and, in turn, also the composite. From a materials design perspective, it is usually desired to avoid brittle fracture without compromising the hardness of the material. Understanding confined ductile fracture is therefore critical for modeling the mechanical response of composite materials with fine microstructure. The present work is focused on confined ductile fracture of a thin ductile film, with elasto-plastic power-law hardening behavior, sandwiched between ideal linear elastic substrates. Fracture of the ductile layer is modeled by growth and coalescence of prescribed voids in 2D. Influences of material properties, initial void volume fraction, geometric constraints and elastic mismatch are investigated. The results show a loss of ductility with decreasing film thickness that is accompanied by a severe decrease in fracture initiation toughness as well as an increased stress at the interface. The influence of materials properties is significant in all cases while the effect of initial void volume fraction is comparatively less critical for highly confined materials than for bulk materials. Increasing confinement also results in increasing normal stress at the phase interface, promoting interface decohesion prior to ductile fracture of the film. The present approach and results are a step towards more detailed prediction of composite fracture toughness and crack-growth resistance.
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