| 1. |
- Dudarev, S. L., et al.
(författare)
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The EU programme for modelling radiation effects in fusion reactor materials : An overview of recent advances and future goals
- 2009
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Ingår i: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 386, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- The EU fusion materials modelling programme was initiated in 2002 with the objective of developing a comprehensive set of computer modelling techniques and approaches, aimed at rationalising the extensive available experimental information on properties of irradiated fusion materials, developing capabilities for predicting the behaviour of materials under conditions not yet accessible to experimental tests, assessing results of tests involving high dose rates, and extrapolating these results to the fusion-relevant conditions. The programme presently gives emphasis to modelling a single class of materials, which are ferritic-martensitic EUROFER-type steels, and focuses on the investigation of key physical phenomena and interpretation of experimental observations. The objective of the programme is the development of computational capabilities for predicting changes in mechanical properties, hardening and embrittlement, as well as changes in the microstructure and phase stability of EUROFER and FeCr model alloys occurring under fusion reactor relevant irradiation conditions.
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| 2. |
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| 3. |
- Victoria, M., et al.
(författare)
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Modelling irradiation effects in fusion materials
- 2007
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Ingår i: Fusion engineering and design. - : Elsevier BV. - 0920-3796 .- 1873-7196. ; 82:15-24, s. 2413-2421
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Tidskriftsartikel (refereegranskat)abstract
- We review the current status of the European fusion materials modelling programme. We describe recent findings and outline potential areas for future development. Large-scale density functional theory (DFT) calculations reveal the structure of the point defects in alpha-Fe, and highlight the crucial part played by magnetism. The calculations give accurate migration energies of point defects and the strength of their interaction with He atoms. Kinetic models based on DFT results reproduce the stages of radiation damage recovery in iron, and stages of He-desorption from pre-implanted iron. Experiments aimed at validating the models will be carried out in the future using a multi-beam ion irradiation facility chosen for its versatility and rapid feedback.
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| 4. |
- Björkas, C., et al.
(författare)
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Simulation of displacement cascades in Fe90Cr10 using a two band model potential
- 2008
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Ingår i: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 372:2-3, s. 312-317
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Tidskriftsartikel (refereegranskat)abstract
- Molecular dynamics (MD) simulations of displacement cascades, with recoil energies up to 50 keV, have been performed in Fe90Cr10 and Fe using a recently developed two band embedded atomic model (2BM) potential that correctly describes the mixing enthalpy and the binding energy of the mixed dumbbell configurations. Comparisons between results obtained with the 2BM potential fitted to different data sets, a one band model (1BM), and another existing FeCr-potential previously used for similar calculations were done, showing differences in the vacancy clustered fraction and the Cr content in interstitials predicted by the potentials. The 2BM potential resulted in roughly the same concentration of Cr in interstitial positions as in the matrix, and the 1BM, which incorrectly predicts a positive heat of mixing, predicted even smaller concentrations. The calculated short range order parameter is around zero for the 2BM, and takes positive values within the 1BM, as expected from the mixing enthalpies.
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| 5. |
- Bonny, G., et al.
(författare)
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Numerical prediction of thermodynamic properties of iron-chromium alloys using semi-empirical cohesive models : The state of the art
- 2009
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Ingår i: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 385:2, s. 268-277
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Tidskriftsartikel (refereegranskat)abstract
- In this work the capability of existing cohesive models to predict the thermodynamicproperties of Fe-Cr alloys are critically evaluated and compared. The two-band model and the concentration-dependent model, which are independently developed extensions of the embedded-atom method, are demonstrated to be equivalent and equally capable of reproducing the thermodynamic properties of Fe-Cr alloys. The existing potentials fitted with these formalisms are discussed and compared with an existing cluster expansionmodel. The phase diagram corresponding to these models is evaluated using different but complementary methods. The influence of mixing enthalpy, low-energy states and vibrational entropy on the phase diagram is examined for the different cohesive models.
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| 6. |
- Juslin, N., et al.
(författare)
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Simulation of threshold displacement energies in FeCr
- 2007
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier BV. - 0168-583X .- 1872-9584. ; 255:1, s. 75-77
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the role of chromium on threshold displacement energies in FeCr for the fusion reactor steel relevant concentration 10% Cr. We have used molecular dynamics simulations in order to determine whether the observed Cr-content dependence of macroscopic properties can be due to the defect production. We compare FeCr-alloys with pure iron and chromium, employing two different potential sets for the Fe-Cr system. We find that there are no significant differences between pure iron and FeCr with 10% Cr for the 100, 110 and 111 directions and the average threshold energy.
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| 7. |
- Malerba, L., et al.
(författare)
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Modelling of Radiation Damage in Fe-Cr Alloys
- 2008
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Ingår i: EFFECTS OF RADIATION ON MATERIALS. - 9780803134218 ; , s. 159-176
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Konferensbidrag (refereegranskat)abstract
- High-Cr ferritic/martensitic steels are being considered as structural materials for a large number of future nuclear applications, from fusion to accelerator-driven systems and GenIV reactors. Fe-Cr alloys can be used as model materials to investigate some of the mechanisms governing their microstructure evolution under irradiation and its correlation to changes in their macroscopic properties. Focusing on these alloys, we show an example of how the integration of computer simulation and theoretical models can provide keys for the interpretation of a host of relevant experimental observations. In particular we show that proper accounting for two basic features of these alloys, namely, the existence of a fairly strong attractive interaction between self-interstitials and Cr atoms and of a mixing enthalpy that changes sign from negative to positive around 8 to 10 % Cr, is a necessary and, to a certain extent, sufficient condition to rationalize and understand their behavior under irradiation. These features have been revealed by ab initio calculations, are supported by experimental evidence, and have been adequately transferred into advanced empirical interatomic potentials, which have been and are being used for the simulation of damage production, defect behavior, and phase transformation in these alloys. The results of the simulations have been and are being used to parameterize models capable of extending the description of radiation effects to scales beyond the reach of molecular dynamics. The present paper intends to highlight the most important achievements and results of this research activity.
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| 8. |
- Malerba, L., et al.
(författare)
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Modelling of radiation damage in Fe-Cr alloys
- 2007
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Ingår i: Journal of ASTM International. - 1546-962X. ; 4:6
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Tidskriftsartikel (refereegranskat)abstract
- High-Cr ferritic/martensitic steels are being considered as structural materials for a large number of future nuclear applications, from fusion to accelerator-driven systems and GenIV reactors. Fe-Cr alloys can be used as model materials to investigate some of the mechanisms governing their microstructure evolution under irradiation and its correlation to changes in their macroscopic properties. Focusing on these alloys, we show an example of how the integration of computer simulation and theoretical models can provide keys for the interpretation of a host of relevant experimental observations. In particular we show that proper accounting for two basic features of these alloys, namely, the existence of a fairly strong attractive interaction between self-interstitials and Cr atoms and of a mixing enthalpy that changes sign from negative to positive around 8 to 10% Cr, is a necessary and, to a certain extent, sufficient condition to rationalize and understand their behavior under irradiation. These features have been revealed by ab initio calculations, are supported by experimental evidence, and have been adequately transferred into advanced empirical interatomic potentials, which have been and are being used for the simulation of damage production, defect behavior, and phase transformation in these alloys. The results of the simulations have been and are being used to parameterize models capable of extending the description of radiation effects to scales beyond the reach of molecular dynamics. The present paper intends to highlight the most important achievements and results of this research activity.
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| 9. |
- Nordlund, K., et al.
(författare)
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Molecular dynamics simulations of threshold displacement energies in Fe
- 2006
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier BV. - 0168-583X .- 1872-9584. ; 246:2, s. 322-332
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Tidskriftsartikel (refereegranskat)abstract
- We compare systematically the threshold displacement energy surface of 11 interatomic potentials in Fe. We discuss in detail different possible definitions of threshold displacement energies, and how they relate to different kinds of experimental threshold displacement energies. We compare the threshold results to experiments, and find that none of the 11 tested potentials agrees fully with experiments. However, all the potentials predict some qualitative features in the same way, most importantly that the threshold energy surface close to the 100 crystal direction is flat and that the largest threshold energies occur around very roughly the 123 crystal direction.
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| 10. |
- Olsson, Pär, et al.
(författare)
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Two-band modeling of alpha-prime phase formation in Fe-Cr
- 2005
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 72:21
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Tidskriftsartikel (refereegranskat)abstract
- We have developed a two-band model of Fe-Cr, fitted to properties of the ferromagnetic alloy. Fitting many-body functionals to the calculated mixing enthalpy of the alloy and the mixed interstitial binding energy in iron, our potential reproduces changes in sign of the formation energy as a function of Cr concentration. When applied in kinetic Monte Carlo simulations, the potential correctly predicts decomposition of initially random Fe-Cr alloys into the alpha-prime phase as function of Cr concentration.
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