Structure and energetics of Y-Ti-O nanoclusters in bcc Fe


Structure and energetics of Y-Ti-O nanoclusters in bcc Fe

Vallinayagam, M.; Posselt, M.; Faßbender, J.

Nanostructured Ferritic Alloys (NFA) are considered as promising candidates for the structural materials of future fusion and fission reactors [1]. They consist of a ferritic or ferritic/martensitic Fe-Cr matrix with a high dispersion of nanometer size yttria-based oxide particles. In this research project (started in November 2016) the nature of nanometer-size yttria-based oxide clusters in a bcc Fe matrix shall be investigated by DFT calculations. The main goal of these studies is the better understanding of the nucleation as well as the structure and composition of the nanoclusters. The investigations shall clarify the conditions for the formation of nonstoichiometric clusters that are coherent with the bcc lattice and for the formation of oxide phases (in particular Y2O3 and Y2Ti2O7). The energetics of the different structures shall be determined and compared. Furthermore, the interaction of the nanoparticles with intrinsic point defects and He atoms shall be studied. Preliminary studies and their results on structure and energetics of certain Y-Ti-O nanoclusters will be presented on the poster. Two models are considered: (i) clusters consisting of Y, Ti, and O atoms on substitutional or defect sites of the bcc lattice [2-4], and (ii) cluster consisting of parts of the bixbyite (Y2O3) or pyrochlore (Y2Ti2O7) structure embedded in bcc Fe [5].
[1] G. R. Odette, JOM-J. Min. Met. Mat. S. 66, 2427 (2014)
[2] D. Murali, B.K. Panigrahi, M.C. Valsakumar, S. Chandra, C.S. Sundar, B. Raj, J. Nucl. Mater. 403, 113 (2010)
[3] A. Claisse, P. Olsson, Nucl. Instr. Meth. B 303, 18 (2013)
[4] M. Posselt, D. Murali, B. K. Panigrahi, Model. Simul. Mater. Sc. 22, 085003 (2014)
[5] L. Barnard, G. R. Odette, I. Szlufarska, D. Morgan. Acta Mater. 60 (2012) 935 (2012)

Keywords: oxide nanoclusters; bcc Fe; nanoferritic alloy; DFT

  • Poster
    NSF/CECAM School on Computational Materials Science: From Basics to Applications, 17.-27.07.2017, Lausanne, Switzerland

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