Advances in synchrotron x-ray diffraction and transmission electron microscopy techniques for the investigation of micro
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S.P. Thompson Diamond Light Source, Didcot, Oxfordshire OX11 0DE, United Kingdom
D. Jädernäs Studsvik Nuclear AB, SE 611 82, Nyköping, Sweden
J. Romero Westinghouse Electric Company, Columbia, South Carolina, USA
L. Hallstadius Westinghouse Electric Sweden AB, SE 72163 Västerås, Sweden
M. Preuss The University of Manchester, Manchester Materials Science Centre, Manchester M13 9PL, United Kingdom (Received 15 September 2014; accepted 9 February 2015)
Transmission electron microscopy (TEM) studies provide mechanistic understanding of nanoscale processes, whereas advanced synchrotron XRD (SXRD) enables precise measurements on volumes that are more representative of bulk materials. Therefore, the combined strengths of these techniques can provide new insight into irradiation-induced mechanistic processes. In the present study, their application to Zircaloy-2, proton-irradiated to 2.3, 4.7, and 7.0 dpa at 2 MeV and 350 °C and neutron-irradiated to 9.5 and 13.1 1025 n m2 are exemplified. The application of correlative spectral imaging and structural TEM investigations to the phase transformation of Zr(Fe,Nb)2 precipitates in Low-Sn ZIRLO™, neutron-irradiated to 8.9–9 1025 n m2, demonstrates the possibility of a Cr core nucleation site. Anomalous broadening is observed in SXRD profiles, which is believed to be caused by defect clusters and precursors to dislocation loop nucleation. The challenges to quantitative analysis of dislocations by SXRD are highlighted with reference to the segregation of Fe and Ni to basal planes and dislocation cores, observed by spectral imaging in the TEM.
I. INTRODUCTION
Zirconium (Zr) alloys are commonly used as the cladding and channel materials in reactor cores of water-cooled reactors. It is, therefore, necessary to investigate the irradiation-induced damage phenomena that can limit the lifetime of these components. Under neutron irradiation, Zr alloys exhibit irradiation-induced growth and creep,1,2 an anisotropic volume-conserving shape change that results in an axial elongation and radial reduction, the extent of which depends on the irradiation species and fluence, the flux and temperature, and the alloy composition, microstructure, and texture.3–8 For fully recrystallized material, this change occurs at an accelerated rate in the “breakaway” regime at fluences Contributing Editor: Djamel Kaoumi a) Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2015.65 J. Mater. Res., 2015
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above ;5 1025 n m2 in light water reactors at 292 °C.4 Microstructural and microchemical analysis is important in determining the mechanistic factors that contribute to the macroscopic growth process, and such features have traditionally been studied by using laboratory x-ray diffraction (LXRD) and transmission electron microscopy (TEM) techniques. The focus of the present study is to demonstrate how advances in these two techniques allow for a more detailed analysis of irradiated material, and furth
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