0000000000115342
AUTHOR
Anton Möslang
Investigation of precipitate in an austenitic ODS steel containing a carbon-rich process control agent
This work has been carried out within the framework of the German Helmholtz Association and has received funding from the topic “Materials Research for the Future Energy Supply”. The work of M. Parish and Rainer Ziegler is gratefully acknowledged. Thanks are also due to the team of the chemical laboratory at the KIT for performing the chemical analysis. The help of the beamline staff at ELETTRA (project 20140052 ) synchrotron radiation facility is acknowledged. We acknowledge support by Deutsche Forschungsgemeinschaft and Open Access Publishing Fund of Karlsruhe Institute of Technology.
Ab initio modelling of Y-O cluster formation in γ-Fe lattice
Ab initio modelling of Y and O impurity atoms as well as VFe vacancies in the fcc-Fe lattice is performed in order to calculate the interactions between these defects, which are important for understanding of nanoparticles’ formation within the oxide dispersed strengthened steels. Large scale parallel calculations based on plane-wave method realised in VASP computer code show that VFe vacancies considerably influence the binding between the impurity atoms. In this study, we present the results of performed calculations providing the detailed information about the binding energies between the defects, the changes of their effective charges as well as displacements of the substitute atoms rel…
Modeling of yttrium, oxygen atoms and vacancies in γ-iron lattice
Abstract Development of the oxide dispersion strengthened (ODS) steels for fission and fusion reactors requires a deep understanding of the mechanism and kinetics of Y 2 O 3 nanoparticle precipitation in the steel matrix. Therefore, it is necessary to perform a large-scale theoretical modeling of the Y 2 O 3 formation. In the current study, a series of first-principles calculations have been performed on different elementary clusters consisting of pair and triple solute atoms and containing: (i) the Y–Fe-vacancy pairs, (ii) the two Y atoms substituted for Fe lattice atoms and (iii) the O impurity atoms dissolved in the steel matrix. The latter is represented by a face-centered cubic γ-Fe si…
Interaction Between Oxygen and Yttrium Impurity Atoms as well as Vacancies in fcc Iron Lattice: Ab Initio Modeling
Synthesis of advanced radiation-resistant steels as construction materials for nuclear reactors, which contain the uniformly distributed yttria precipitates (ODS steels), is an important task for ecological security of nuclear plants. The initial stage of theoretical simulation on oxide cluster growth in the steel matrix is a large-scale ab initio modeling on pair- and triple-wise interaction between the Y and O impurity atoms as well as Fe vacancies, including their different combinations, in the paramagnetic face-centered-cubic (fcc) iron lattice. Calculations on the pair of Y atoms have shown that no bonding appears between them, whereas a certain attraction has been found between Y subs…
Ab initio modelling of the initial stages of the ODS particle formation process
Abstract Oxide-Dispersion Strengthened (ODS) steels with Y2O3 nanoparticles are promising structural materials for fision and future fusion reactors. A large number of experimental as well as theoretical studies provided valuable information on the ODS particle formation process. However, some important details of this process still remain unexplained. We present the results of ab initio VASP calculations of the initial steps of the ODS particle formation. At these steps Y solute atoms are stabilized in the Fe lattice by vacancies, which create a basis for the future growth of Y2O3-particle. Interaction of multiple vacancies and solution Y and O atoms has been studied in various combination…
Ab initio modelling of the Y, O, and Ti solute interaction in fcc-Fe matrix
Abstract Strengthening of the ODS steels by Y2O3 precipitates permits to increase their operation temperature and radiation resistance, which is important in construction materials for future fusion and advanced fission reactors. Both size and spatial distribution of oxide particles significantly affect mechanical properties and radiation resistance of ODS steels. Addition of the Ti species (present also as a natural impurity atoms in iron lattice) in the particles of Y2O3 powder before their mechanical alloying leads to the formation of YTiO3, Y2TiO5, and Y2Ti2O7 nanoparticles in ODS steels. Modelling of these nanoparticle formation needs detailed knowledge of the energetic interactions be…
Ab initio simulation of yttrium oxide nanocluster formation on fcc Fe lattice
Using results of density functional theory (DFT) calculations the first attempt towards the understanding of Y2O3 particles formation in oxide dispersed strengthened (ODS) ferritic–martensitic steels was performed. The present work includes modeling of single defects (O impurity atom, Fe vacancy and Y substitute atom), interaction between substituted Y atoms, Y–Fe vacancy pairs and oxygen impurity atoms in the iron matrix. The calculations have showed the repulsive interaction between the two Y substitute atoms at any separation distances that might mean that the oxygen atoms or O atoms with vacancies are required to form binding between atoms in the yttrium oxide nanoclusters.