TY - JOUR
T1 - Structure of zirconium alloy oxides formed in pure water studied with synchrotron radiation and optical microscopy
T2 - Relation to corrosion rate
AU - Yilmazbayhan, Aylin
AU - Motta, Arthur T.
AU - Comstock, Robert J.
AU - Sabol, George P.
AU - Lai, Barry
AU - Cai, Zhonghou
N1 - Funding Information:
The authors would like to thank Sarah Jurgensmeier (Penn State) and Jonna Partezana (Westinghouse) for assistance with the experiments and Marcelo Silva (Penn State) for assistance with the peak fitting effort. We also thank Randy Lott of Westinghouse and Jean-Luc Béchade of CEA-Saclay for many helpful discussions. Use of the Advanced Photon Source was supported by the US Department of Energy, Basic Energy Sciences, Office of Science, under Contract No. W-31-109-Eng-38. This research was sponsored by the Department of Energy, Nuclear Engineering Research Initiative (DOE-NERI) program, under grant number DE-FC03-99SF21918.
PY - 2004/1/1
Y1 - 2004/1/1
N2 - A detailed study was undertaken of oxides formed in 360 °C water on four Zr-based alloys (Zircaloy-4, ZIRLO™, ZIRLO is a trademark of Westinghouse Electric Co.1 Zr-2.5%Nb and Zr-2.5%Nb-0.5%Cu) in an effort to relate oxide structure to corrosion performance. Micro-beam X-ray diffraction was used along with transmitted light optical microscopy to obtain information about the structure of these oxides as a function of distance from the oxide-metal interface. Optical microscopy revealed a layered oxide structure in which the average layer thickness was inversely proportional to the post-transition corrosion rate. The detailed diffraction studies showed an oxide that contained both tetragonal and monoclinic ZrO2, with a higher fraction of tetragonal oxide near the oxide-metal interface, in a region roughly corresponding to one oxide layer. Evidence was seen also of a cyclic variation of the tetragonal and monoclinic oxide across the oxide thickness with a period of the layer thickness. The results also indicate that the final grain size of the tetragonal phase is smaller than that of the monoclinic phase and the monoclinic grain size is smaller in Zircaloy-4 and ZIRLO than in the other two alloys. These results are discussed in terms of a model of oxide growth based on the periodic breakdown and reconstitution of a protective layer.
AB - A detailed study was undertaken of oxides formed in 360 °C water on four Zr-based alloys (Zircaloy-4, ZIRLO™, ZIRLO is a trademark of Westinghouse Electric Co.1 Zr-2.5%Nb and Zr-2.5%Nb-0.5%Cu) in an effort to relate oxide structure to corrosion performance. Micro-beam X-ray diffraction was used along with transmitted light optical microscopy to obtain information about the structure of these oxides as a function of distance from the oxide-metal interface. Optical microscopy revealed a layered oxide structure in which the average layer thickness was inversely proportional to the post-transition corrosion rate. The detailed diffraction studies showed an oxide that contained both tetragonal and monoclinic ZrO2, with a higher fraction of tetragonal oxide near the oxide-metal interface, in a region roughly corresponding to one oxide layer. Evidence was seen also of a cyclic variation of the tetragonal and monoclinic oxide across the oxide thickness with a period of the layer thickness. The results also indicate that the final grain size of the tetragonal phase is smaller than that of the monoclinic phase and the monoclinic grain size is smaller in Zircaloy-4 and ZIRLO than in the other two alloys. These results are discussed in terms of a model of oxide growth based on the periodic breakdown and reconstitution of a protective layer.
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U2 - 10.1016/j.jnucmat.2003.08.038
DO - 10.1016/j.jnucmat.2003.08.038
M3 - Article
AN - SCOPUS:0345016313
VL - 324
SP - 6
EP - 22
JO - Journal of Nuclear Materials
JF - Journal of Nuclear Materials
SN - 0022-3115
IS - 1
ER -