Tin clustering and precipitation in the oxide during autoclave corrosion of Zircaloy-2
Journal article, 2015

Atom probe tomography has been used to study the evolution of tin distribution during the corrosion process in Zircaloy-2. From being completely soluble in the Zr metal matrix, some clustering is evident already in the newly formed oxide close to the metal-oxide interface. Analysis of thicker oxides a few hundred nanometers away from the interface reveals fully developed precipitates of metallic Sn particles of up to 20 nm in size. Although the precipitates contain significant amounts of Zr, it is concluded that they are in the process of being depleted in Zr, which is limited only by the slow diffusion in the oxide scale. The findings are interpreted as being a result of the nobility of the Sn yielding a strong driving force to remain in a metallic state after incorporation in the barrier oxide layer. As Sn occupies substitutional sites in the ZrO2 lattice it is oxidized to a 4+ state when incorporated into the oxide, and in order to remain metallic it must nucleate into precipitates within the inner part of the oxide scale before being re-oxidized to 2+ and eventually to 4+ when the oxygen activity is sufficiently high in the outer parts of the oxide.

Zircaloy-2

atom probe tomography

zirconium oxide

Sn

precipitation

corrosion

Author

Gustav Sundell

Chalmers, Applied Physics, Materials Microstructure

Mattias Thuvander

Chalmers, Applied Physics, Materials Microstructure

Hans-Olof Andrén

Chalmers, Applied Physics, Materials Microstructure

Journal of Nuclear Materials

0022-3115 (ISSN)

Vol. 456 409-414

Areas of Advance

Energy

Materials Science

Subject Categories

Other Materials Engineering

Corrosion Engineering

DOI

10.1016/j.jnucmat.2014.10.003

More information

Created

10/8/2017