Microstructural characterization of the ζ- and γ-hydride phases in Zircaloy-2 by Electron Diffraction and Energy-Loss Spectroscopy Techniques.

dc.contributor.authorNikpoor Badr, Nimaen
dc.contributor.departmentMechanical and Materials Engineeringen
dc.contributor.supervisorDaymond, Mark
dc.contributor.supervisorYao, Zhongwen
dc.date.accessioned2023-03-16T15:21:28Z
dc.date.available2023-03-16T15:21:28Z
dc.degree.grantorQueen's University at Kingstonen
dc.description.abstractIn this study, the formation of the ζ- and γ-hydride phases in the form of independent bulk precipitates and interfacial ribbons between δ-precipitates and α-Zr matrix was investigated. Energy-Loss Spectroscopy (EELS) and Nano-Beam Electron Diffraction (NBED) techniques were utilized to characterize nano-hydrides formed in water-quench and furnace-cool conditions. For δ-nano-hydrides, EELS measured two ~10 nm-wide ribbons with plasmon energy (PE) values of 17.4±0.3 eV and ~18.3±0.3 eV (characteristic of the ζ- and γ-phases, respectively) surrounding the δ-core. Complementary NBED characterization of multiple zone axes of the interface, however, did not suggest the existence of the ζ- or γ-phases in the interface. Next, it was attempted to clarify why the characteristic PE values of the ζ- and γ-phases were observed in the interface. For this purpose, energy-loss spectra of the α-Zr and δ-hydride phases were simulated in interfacial areas between the two phases. Simulations predicted a gradual shift of PE between 16.9-19.2 eV over a ~5 nm distance due to the interface effect. In addition, a delocalization length of ~16 nm was measured for the 16-20 eV energy-loss window. Results showed that the observed interfacial ribbons stemmed from a combination of the interface effect and the delocalized nature of the plasmon vibration, and not from the formation of interfacial ζ- and γ-ribbons. In the next step, the formation of the ζ- and γ-phases as bulk precipitates was investigated. Synchrotron X-ray diffraction examination of water-quenched hydrides revealed a diffraction peak at the d-spacing value ~2.70 Å, which can stem from either the (0004)ζ or {111}γ planes. In a quest for the bulk ζ-precipitates, nano-hydrides were characterized in [0001], <112̅6>, <101̅4>, and <112̅0> orientations where NBED patterns identical to those reported for the ζ-phase in previous works were collected. Analysis of electron diffraction patterns revealed that reflections that are conventionally attributed to the ζ-phase, in fact, originate from either the δ-phase covered with a thin surface phase (probably Zr-oxide) or dynamical scattering events between the α-Zr and δ-hydride in overlapped areas. Finally, EELS and NBED detected only the γ- and δ-phases in the microstructure, but not the ζ-phase.en
dc.description.degreePhDen
dc.embargo.liftdate2028-03-15T21:15:36Z
dc.embargo.termsPlease consider this thesis as restricted. We need to publish some chapters of the thesis in journal articles first.en
dc.identifier.urihttp://hdl.handle.net/1974/31480
dc.language.isoengen
dc.relation.ispartofseriesCanadian thesesen
dc.rightsQueen's University's Thesis/Dissertation Non-Exclusive License for Deposit to QSpace and Library and Archives Canadaen
dc.rightsProQuest PhD and Master's Theses International Dissemination Agreementen
dc.rightsIntellectual Property Guidelines at Queen's Universityen
dc.rightsCopying and Preserving Your Thesisen
dc.rightsThis publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.en
dc.subjectZirconium hydridesen
dc.subjectZircaloyen
dc.subjectTransmission Electron Microscopyen
dc.subjectElectron Energy Loss spectroscopyen
dc.subjectElectron diffractionen
dc.subjectPlasmon energyen
dc.titleMicrostructural characterization of the ζ- and γ-hydride phases in Zircaloy-2 by Electron Diffraction and Energy-Loss Spectroscopy Techniques.en
dc.typethesisen
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