Osman El Atwani

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"In-situ irradiation tolerance investigation of high strength ultrafine tungsten-titanium carbide alloy" Osman El Atwani, Acta Materialia Vol. 164 2019 547-559
"In-situ observation of nano-oxide and defect evolution in 14YWT alloys" Osman El Atwani, Meimei Li, Stuart Maloy, Eda Aydogan, Materials Characterization Vol. 170 2020 110686
Nanostructured ferritic alloys (NFAs) are considered as candidates for structural components in advanced nuclear reactors due to their excellent radiation resistance as a result of a high density of nano-oxides (NOs) in the microstructure. Therefore, gaining an understanding on the stability of NOs under irradiation is crucial. In this study, we have investigated the evolution of defects and NOs in 14YWT NFAs under in-situ Kr ion irradiation at room temperature (RT) and 450 °C up to 10 dpa. It has been found that irradiations at 450 °C do not create any changes in the NOs, similar to the bulk irradiations. On the other hand, elemental mapping indicates that NOs dissolve mostly after 10 dpa irradiations at RT. Thus, while defects are both annihilated and pinned by NOs at low doses (before the dissolution of NOs), glissile loops start to escape to the foil surface at high doses (after the dissolution of NOs), justifying the significantly low fraction of <111> loops compared to the literature values. High resolution transmission electron microscopy analysis has shown that the NOs are mostly coherent Y2Ti2O7 particles with pyrochlore crystal structure after both RT and 450 °C irradiations, similar to those observed before irradiation.
"In-situ radiation response of additively manufactured modified Inconel 718 alloys" Eda Aydogan, Osman El Atwani, Begum Erdem, Wei-Ying Chen, Meimei Li, ARUN DEVARAJ, Bahattin Koc, Stuart Maloy, Additive Manufacturing Vol. 51 2022 102601
In this study, a novel alloy of modified Inconel 718 produced by laser powder bed fusion is studied before and after in-situ Kr irradiation up to 3 dpa at 200 and 450 °C. Before irradiation, the microstructure consists of dislocation cells having a misorientation angle less than 5° and with an average size of ~500 nm. There are also second phase particles of MC type carbides, Laves phase and oxides such as Y-O, Y-(Ti)-Al-O. While the microstructure consists of stacking fault tetrahedra, faulted and perfect loops after irradiation at 200 °C, dislocation loops are the primary defects at 450 °C. With increasing dose, the size of the defects remains similar at 200 °C while it increases at 450 °C. This has been attributed to the existence of vacancy type defects at 200 °C and the different defect transport mechanisms at different temperatures. Moreover, matrix and second phase particle compositions seem to be similar after irradiation. The sink strengths of the structures have been calculated and superior radiation resistance of this alloy has been attributed to the existence of fine cell boundaries stabilized by the second phase particles produced by additive manufacturing.
"Nanohardness measurements of heavy ion irradiated coarse- and nanocrystalline-grained tungsten at room and high temperature" Osman El Atwani, Jordan Weaver, JESUS ALFREDO ESQUIVEL, Yongqiang Wang, Stuart Maloy, Nathan Mara, Journal of Nuclear Materials Vol. 509 2018 276-284 Link
"Outstanding radiation resistance of tungsten-based high-entropy alloys" Osman El Atwani, Science Advances Vol. 5 2019 eaav2002
"Unprecedented irradiation resistance of nanocrystalline tungsten with equiaxed nanocrystalline grains to dislocation loop accumulation" Osman El Atwani, Acta Materialia Vol. 165 2019 118-128 Link
NSUF Articles:
U.S. DOE Nuclear Science User Facilities Awards 30 Rapid Turnaround Experiment Research Proposals - Awards total nearly $1.2 million The U.S. Department of Energy (DOE) Nuclear Science User Facilities (NSUF) has selected 30 new Rapid Turnaround Experiment (RTE) projects, totaling up to approximately $1.2 million. These projects will continue to advance the understanding of irradiation effects in nuclear fuels and materials in support of the mission of the DOE Office of Nuclear Energy. Wednesday, April 26, 2017 - Calls and Awards
DOE-NE Awards 19 RTE Projects - New projects total approximately $690K Thursday, February 6, 2020 - Announcement, Calls and Awards, Newsletter, News Release