SYMPOSIA PAPER Published: 01 January 1994
STP15212S

Examinations of the Corrosion Mechanism of Zirconium Alloys

Source

Several mechanism-related aspects of the corrosion of zirconium alloys have been investigated using different examination techniques. The microstructure of different types of oxide layers was analyzed by transmission electron microscopy (TEM). Uniform oxide mainly consists of m-ZrO2 and a smaller fraction of t-ZrO2 with columnar grains and some amount of equiaxed crystallites. Nodular oxides show a high open porosity and the grain shape tends to the equiaxed type. A fine network of pores along grain boundaries was found in oxides grown in water containing lithium. An enrichment of lithium within such oxides could be found by glow discharge optical spectroscopy (GD-OES) depth profiling. In all oxides, a compact, void-free oxide layer was observed at the metal/oxide interface. Compressive stresses within the oxide layer measured by an X-ray diffraction technique were significantly higher compared to previously published values. Electrical potential measurements on oxide scales showed the influence of the intermetallic precipitates on the potential drop across the oxide. In long-time corrosion tests of Zircaloy with varying temperatures, memory effects caused by the cyclic formation of barrier layers could be observed. It was concluded that the corrosion mechanism of zirconium-based alloys is a barrier-layer controlled process. The protective properties of this barrier layer determine the overall corrosion resistance of zirconium alloys.

Author Information

Beie, HJ
Siemens AG, Corporate Research and Development, Erlangen, Germany
Mitwalsky, A
Siemens AG, Corporate Research and Development, Munich, Germany
Garzarolli, F
Siemens AG, Power Generation Group (KWU), Erlangen, Germany
Ruhmann, H
Siemens AG, Power Generation Group (KWU), Erlangen, Germany
Sell, HJ
Siemens AG, Power Generation Group (KWU), Erlangen, Germany
Price: $25.00
Contact Sales
Related
Reprints and Permissions
Reprints and copyright permissions can be requested through the
Copyright Clearance Center
Details
Developed by Committee: B10
Pages: 615–643
DOI: 10.1520/STP15212S
ISBN-EB: 978-0-8031-5286-1
ISBN-13: 978-0-8031-2011-2