Browsing by Author "Kirk, MA"

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    Defect evolution in a NiMoCrFe alloy subjected to high-dose Kr ion irradiation at elevated temperature
    (Elsevier B.V., 2016-06-01) de los Reyes, M; Voskoboinikov, R; Kirk, MA; Huang, HF; Lumpkin, GR; Bhattacharyya, D
    A candidate NiMoCrFe alloy (GH3535) for application as a structural material in a molten salt nuclear reactor was irradiated with 1 MeV Kr2+ ions (723 K, max dose of 100 dpa) at the IVEM-Tandem facility. The evolution of defects like dislocation loops and vacancy- and self-interstitial clusters was examined in-situ. For obtaining a deeper insight into the true nature of these defects, the irradiated sample was further analysed under a TEM post-facto. The results show that there is a range of different types of defects formed under irradiation. Interaction of radiation defects with each other and with pre-existing defects, e.g., linear dislocations, leads to the formation of complex microstructures. Molecular dynamics simulations used to obtain a greater understanding of these defect transformations showed that the interaction between linear dislocations and radiation induced dislocation loops could form faulted structures that explain the fringed contrast of these defects observed in TEM. © 2016 Elsevier B.V.
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    Microstructural evolution of an ion irradiated Ni–Mo–Cr–Fe alloy at elevated temperatures
    (Materials Transactions, 2014-01-01) de los Reyes, M; Edwards, L; Kirk, MA; Bhattacharyya, D; Lu, KT; Lumpkin, GR
    The irradiation behavior of a Ni–Mo–Cr–Fe alloy, of the type currently being considered for use in future molten salt cooled reactors, has been investigated in situ using 1 MeV Kr ions at temperatures of 723 and 973 K. When irradiated to 5 dpa, experimental observations reveal the instantaneous formation and annihilation of point defect clusters, with such processes attributed to the long range elastic interactions that occur between defects through multiple intra-cascade overlap. Corresponding differences in the defect cluster density and size distribution suggest that changes to the microstructure were dependent upon temperature and dose, affecting the growth, accumulation and mobility of irradiation-induced defect clusters under these conditions. © 2014,The Japan Institute of Metals and Materials.