International Topical Meeting on Nuclear Research Applications and Utilization of Accelerators
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AP/AM-05 Microstructural Investigation of Zirconium Alloys Subjected to Electron, Light and Heavy Ions Irradiations R. Tewari Materials Science Division, Bhabha Atomic Research Centre, Mumbai, India Corresponding Author: rtewaribarc@yahoo.co.in In the present study, microstructures and formation of various phases have been examined in samples of zirconium based alloys irradiated with electron, protons and oxygen ions. In case of oxygen ion irradiation zircaloy-2 have been irradiated by Oxygen with different fluences and the effect of the irradiation has been studied in terms of the defect introduced into the materials. Microstructural investigations on these samples showed the presence of defects and precipitates in the alpha matrix. Composite selected area electron diffraction patterns obtained from the irradiated regions were analysed and it was shown that the precipitate phase was the monoclinic zirconium oxide. Orientation relationship between the oxide and the matrix phase has been determined. In the Zr-20Nb alloy, the formation of the omega phase under electron irradiation has been examined. Samples were exposed to 1 MeV and 2 MeV electrons and SAD patterns were recorded after different durations of irradiation exposure at various temperatures. Detailed post-irradiation examination of the microstructure was subsequently carried out. Thermal treatments as well as irradiation have been found to lead to the formation of diffuse omega maxima. The origin of these maxima has been probed in either case by carrying out high resolution electron microscopy (HREM). The formation of the crystalline omega phase on prolonged irradiation and thermal treatment and its subsequent distribution has also been examined. Irradiation has been found to lead to dissolution of the omega phase in periods of time considerably shorter than those required for thermal treatment. In the case of proton irradiation, the Zr-1Nb alloy has been irradiated with 8 MeV proton. As this energy of proton was higher than the coulombic barrier of the Zr ions, bombardment of protons led into the transmutation of Zr atoms into Nb atoms. Microstructural examination of such samples revealed interesting morphology of the betafnphase (bcc) in the alpha matrix.
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