Modeling of yttrium, oxygen atoms and vacancies in γ-iron lattice

• Published in: Journal of nuclear materials Vol. 416; no. 1; pp. 40 - 44
• Main Authors: Gopejenko, Aleksejs, Zhukovskii, Yuri F., Vladimirov, Pavel V., Kotomin, Eugene A., Möslang, Anton
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 01-09-2011; Elsevier
• Subjects: Applied sciences; Controled nuclear fusion plants; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Fission nuclear power plants; Fuels; Installations for energy generation and conversion: thermal and electrical energy; Nuclear fuels; Martensitic steel; Impurity; Hot isostatic pressing; Oxides; Iron; Dispersion strengthened steel; Modeling; Phase transitions; Nuclear reactor; Nuclear fusion reactor; Concentration effect; Ferritic steel; Yttrium
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/j.jnucmat.2010.11.088

Development of the oxide dispersion strengthened (ODS) steels for fission and fusion reactors requires a deep understanding of the mechanism and kinetics of Y
2O
3 nanoparticle precipitation in the steel matrix. Therefore, it is necessary to perform a large-scale theoretical modeling of the Y
2O
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 single crystal. This structure is relevant because a transition to γ-phase occurs in low Cr ferritic–martensitic steels at typically hot isostatic pressing temperatures. The results clearly demonstrate a certain attraction between the Y substitute and Fe vacancy whereas no binding has been found between the two Y substitute atoms. Results of calculations on different Y–O–Y cluster configurations in lattice show that not only a presence of oxygen atom favors a certain binding between the impurity atoms inside the γ-Fe lattice but also the increased concentration of Fe vacancies is required for the growth of the Y
2O
3 precipitates within the iron crystalline matrix.