Detailed analysis of the microstructure of the metal/oxide interface region in Zircaloy-2 after autoclave corrosion testing
Paper i proceeding, 2011

Two varieties of Zircaloy-2, with different second phase particle (SPP) size distributions and different corrosion resistance, were oxidized in a steam autoclave. Transmission electron microscopy (TEM) of large thin-foil cross-sections of the oxide and the adjacent metal shows an undulating metal/oxide interface in both materials with a periodicity of slightly less than 1 μm and an amplitude of around 100 nm. The SPPs oxidize slower than the surrounding metal, and the absence of volume increase leads to void and crack formation as the SPPs become embedded in the oxide. On SPP oxidation, iron diffuses out of the particles into the surrounding oxide. A sub-oxide with an oxygen content of approximately 50 at. % and a layer thickness of about 200 nm was observed close to the metal/oxide interface. There is a 200 nm oxygen concentration gradient into the metal, from the level close to the sub-oxide of about 30 at. % down to a few atomic percent. All tin in the matrix is incorporated in the sub-oxide, and no segregation to the metal/oxide interface was found.

Oxide crack

SPP

Oxide void

Zircaloy-2

TEM

Atom probe

HAADF

Sub-oxide

Författare

Pia Tejland

Chalmers, Teknisk fysik, Mikroskopi och mikroanalys

Mattias Thuvander

Chalmers, Teknisk fysik, Mikroskopi och mikroanalys

Hans-Olof Andrén

Chalmers, Teknisk fysik, Mikroskopi och mikroanalys

S. Ciurea

Sandvik

Thomas Andersson

Sandvik

Mats Dahlbäck

Westinghouse Electric Sweden AB

Lars Hallstadius

Westinghouse Electric Sweden AB

ASTM Special Technical Publication. 16th International Symposium on Zirconium in the Nuclear Industry, Chengdu, Sinchuan Province, 9-13 May 2010

0066-0558 (ISSN)

Vol. 1529 STP 595-617

Ämneskategorier

Materialteknik

Styrkeområden

Energi

Materialvetenskap

DOI

10.1520/JAI102956

ISBN

978-080317515-0