Studiecentrum Voor Kernenergie Center Detudes Of Lenergie Nucleaire Sck Cen

Mol, Belgium

Studiecentrum Voor Kernenergie Center Detudes Of Lenergie Nucleaire Sck Cen

Mol, Belgium

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Vandermeulen W.,Studiecentrum Voor Kernenergie Center Detudes Of Lenergie Nucleaire Sck Cen | Mertens M.,Flemish Institute for Technological Research | Scibetta M.,Studiecentrum Voor Kernenergie Center Detudes Of Lenergie Nucleaire Sck Cen
Journal of Nuclear Materials | Year: 2012

In a previous study it was shown that the anisotropy of Young's modulus in the stainless steel cladding of a reactor pressure vessel could be attributed to the solidification texture of the cladding. Further it was found that annealing the samples to remove the delta phase caused a modulus change but only in some directions. Since the texture was only estimated from X-ray diffraction patterns the moduli, calculated for some principal directions, differed considerably from the measured ones. In the present study, executed on a practically identical cladding, the texture was determined by actual texture measurements. It was found to be close to a fibre texture with 〈0 0 1〉 perpendicular to the cladding plane and the values calculated from it agreed much better with the experimental ones. The annealing effect found in the previous study was shown to be due to surface recrystallization induced by milling damage. © 2011 Elsevier B.V. All rights reserved.


Castin N.,Studiecentrum Voor Kernenergie Center Detudes Of Lenergie Nucleaire Sck Cen | Castin N.,Free University of Colombia | Pascuet M.I.,CONICET | Malerba L.,Studiecentrum Voor Kernenergie Center Detudes Of Lenergie Nucleaire Sck Cen
Journal of Chemical Physics | Year: 2011

We simulate the coherent stage of Cu precipitation in -Fe with an atomistic kinetic Monte Carlo (AKMC) model. The vacancy migration energy as a function of the local chemical environment is provided on-the-fly by a neural network, trained with high precision on values calculated with the nudged elastic band method, using a suitable interatomic potential. To speed up the simulation, however, we modify the standard AKMC algorithm by treating large Cu clusters as objects, similarly to object kinetic Monte Carlo approaches. Seamless matching between the fully atomistic and the coarse-grained approach is achieved again by using a neural network, that provides all stability and mobility parameters for large Cu clusters, after training on atomistically informed results. The resulting hybrid algorithm allows long thermal annealing experiments to be simulated, within a reasonable CPU time. The results obtained are in very good agreement with several series of experimental data available from the literature, spanning over different conditions of temperature and alloy composition. We deduce from these results and relevant parametric studies that the mobility of Cu clusters containing one vacancy plays a central role in the precipitation mechanism. © 2011 American Institute of Physics.


PubMed | Studiecentrum Voor Kernenergie Center Detudes Of Lenergie Nucleaire Sck Cen
Type: Journal Article | Journal: The Journal of chemical physics | Year: 2011

We simulate the coherent stage of Cu precipitation in -Fe with an atomistic kinetic Monte Carlo (AKMC) model. The vacancy migration energy as a function of the local chemical environment is provided on-the-fly by a neural network, trained with high precision on values calculated with the nudged elastic band method, using a suitable interatomic potential. To speed up the simulation, however, we modify the standard AKMC algorithm by treating large Cu clusters as objects, similarly to object kinetic Monte Carlo approaches. Seamless matching between the fully atomistic and the coarse-grained approach is achieved again by using a neural network, that provides all stability and mobility parameters for large Cu clusters, after training on atomistically informed results. The resulting hybrid algorithm allows long thermal annealing experiments to be simulated, within a reasonable CPU time. The results obtained are in very good agreement with several series of experimental data available from the literature, spanning over different conditions of temperature and alloy composition. We deduce from these results and relevant parametric studies that the mobility of Cu clusters containing one vacancy plays a central role in the precipitation mechanism.

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