TEM of neutron, proton and self-ion irradiation damage in FeCr alloys
<p>In the absence of a high-flux fusion-neutron irradiation source, the microstructural and mechanical changes expected within materials exposed to a nuclear-fusion environment must be replicated by fission-neutron and other surrogate-particle irradiations. This study uses transmission electro...
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| Format: | Thesis |
| Language: | English |
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2018
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| _version_ | 1826316587580260352 |
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| author | Haley, JC |
| author2 | Roberts, S |
| author_facet | Roberts, S Haley, JC |
| author_sort | Haley, JC |
| collection | OXFORD |
| description | <p>In the absence of a high-flux fusion-neutron irradiation source, the microstructural and mechanical changes expected within materials exposed to a nuclear-fusion environment must be replicated by fission-neutron and other surrogate-particle irradiations. This study uses transmission electron microscopy (TEM) to compare the microstructural defects produced in FeCr alloys during exposure to neutrons, protons, and self-ions.</p> <p>Alloys of Fe6Cr and Fe9Cr were irradiated using fission-neutrons, 2.0MeV Fe+ ions and 1.2MeV protons at similar temperatures (~300C) and similar doses (~2.0dpa). The neutron-irradiated alloys contained a population of interstitial dislocation loops with b=<111> (>70%) and b=<100>. The visible dislocation loops were on average ~5nm in size, and the density varied from 2±1 x10<sup>14</sup>cm<sup>-3</sup> in the matrix to 1.2±0.3 x10<sup>17</sup>cm<sup>-3</sup> close to helical dislocation lines. Dislocations loops were mostly clustered around sub-grain boundaries and helical-dislocations. Helical-dislocations formed from initially straight screw dislocations experiencing radial-climb in response to a vacancy-biased defect flux. Small chromium clusters were identified in the neutron-irradiated Fe6Cr, and chromium α’-phase precipitates were identified in the Fe9Cr.</p> <p>Self-ion irradiation produced mostly homogeneously distributed dislocation loops (6-7nm on average), but with a greater fraction of <100> loops (~40%) than was seen in the neutron-irradiated alloys. The self-ion irradiated Fe6Cr and Fe9Cr contained only vacancy-type loops, unlike the neutron or proton irradiated sample which contained only interstitial loops. Chromium remained in solution in both ion-irradiated samples.</p> <p>Proton-irradiated Fe9Cr contained dislocation loops close to helical-dislocation segments, similar to the neutron-irradiated sample. Chromium α’-phases were also identified. The proton-irradiated Fe6Cr contained much larger loops (~13nm on average) than the neutron or ion-irradiated alloys, and chromium was shown to have segregated on and around these loops. Both proton-irradiated alloys contained large voids (>4nm and up to 12nm) at a density greater than 10<sup>16</sup>cm<sup>-3</sup>. In the neutron and ion-irradiated alloys, voids were mostly <2nm.</p> |
| first_indexed | 2024-03-07T07:42:17Z |
| format | Thesis |
| id | oxford-uuid:4b132c2b-d039-43e5-9dd0-2fe786c3323f |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-12-09T03:47:43Z |
| publishDate | 2018 |
| record_format | dspace |
| spelling | oxford-uuid:4b132c2b-d039-43e5-9dd0-2fe786c3323f2024-12-08T10:28:54ZTEM of neutron, proton and self-ion irradiation damage in FeCr alloysThesishttp://purl.org/coar/resource_type/c_db06uuid:4b132c2b-d039-43e5-9dd0-2fe786c3323fNuclear power plants--Materials--Effect of radiation onNuclear fusionTransmission electron microscopyNuclear reactorsMaterialsChromium-iron alloysMaterials--Effect of radiation onNeutron irradiationFerritic steelElectrons--DiffractionNuclear energyEnglishORA Deposit2018Haley, JCRoberts, SLozano-Perez, S<p>In the absence of a high-flux fusion-neutron irradiation source, the microstructural and mechanical changes expected within materials exposed to a nuclear-fusion environment must be replicated by fission-neutron and other surrogate-particle irradiations. This study uses transmission electron microscopy (TEM) to compare the microstructural defects produced in FeCr alloys during exposure to neutrons, protons, and self-ions.</p> <p>Alloys of Fe6Cr and Fe9Cr were irradiated using fission-neutrons, 2.0MeV Fe+ ions and 1.2MeV protons at similar temperatures (~300C) and similar doses (~2.0dpa). The neutron-irradiated alloys contained a population of interstitial dislocation loops with b=<111> (>70%) and b=<100>. The visible dislocation loops were on average ~5nm in size, and the density varied from 2±1 x10<sup>14</sup>cm<sup>-3</sup> in the matrix to 1.2±0.3 x10<sup>17</sup>cm<sup>-3</sup> close to helical dislocation lines. Dislocations loops were mostly clustered around sub-grain boundaries and helical-dislocations. Helical-dislocations formed from initially straight screw dislocations experiencing radial-climb in response to a vacancy-biased defect flux. Small chromium clusters were identified in the neutron-irradiated Fe6Cr, and chromium α’-phase precipitates were identified in the Fe9Cr.</p> <p>Self-ion irradiation produced mostly homogeneously distributed dislocation loops (6-7nm on average), but with a greater fraction of <100> loops (~40%) than was seen in the neutron-irradiated alloys. The self-ion irradiated Fe6Cr and Fe9Cr contained only vacancy-type loops, unlike the neutron or proton irradiated sample which contained only interstitial loops. Chromium remained in solution in both ion-irradiated samples.</p> <p>Proton-irradiated Fe9Cr contained dislocation loops close to helical-dislocation segments, similar to the neutron-irradiated sample. Chromium α’-phases were also identified. The proton-irradiated Fe6Cr contained much larger loops (~13nm on average) than the neutron or ion-irradiated alloys, and chromium was shown to have segregated on and around these loops. Both proton-irradiated alloys contained large voids (>4nm and up to 12nm) at a density greater than 10<sup>16</sup>cm<sup>-3</sup>. In the neutron and ion-irradiated alloys, voids were mostly <2nm.</p> |
| spellingShingle | Nuclear power plants--Materials--Effect of radiation on Nuclear fusion Transmission electron microscopy Nuclear reactors Materials Chromium-iron alloys Materials--Effect of radiation on Neutron irradiation Ferritic steel Electrons--Diffraction Nuclear energy Haley, JC TEM of neutron, proton and self-ion irradiation damage in FeCr alloys |
| title | TEM of neutron, proton and self-ion irradiation damage in FeCr alloys |
| title_full | TEM of neutron, proton and self-ion irradiation damage in FeCr alloys |
| title_fullStr | TEM of neutron, proton and self-ion irradiation damage in FeCr alloys |
| title_full_unstemmed | TEM of neutron, proton and self-ion irradiation damage in FeCr alloys |
| title_short | TEM of neutron, proton and self-ion irradiation damage in FeCr alloys |
| title_sort | tem of neutron proton and self ion irradiation damage in fecr alloys |
| topic | Nuclear power plants--Materials--Effect of radiation on Nuclear fusion Transmission electron microscopy Nuclear reactors Materials Chromium-iron alloys Materials--Effect of radiation on Neutron irradiation Ferritic steel Electrons--Diffraction Nuclear energy |
| work_keys_str_mv | AT haleyjc temofneutronprotonandselfionirradiationdamageinfecralloys |