Irradiation of metals with energetic particles causes heavy damage effects in microstructure and
mechanical properties, which is closely associated with irradiation conditions, presence of
impurities, and microstructural features. It has been proposed that the radiation tolerance of a
certain material can be enhanced by introducing a high density of interfaces, acting as ‘sinks’ that
can frequently involve in attracting, absorbing and annihilating defects. Nanostructured materials
with large volume fraction of interfaces, therefore, are assumed to be more radiation tolerant than
conventional materials. This thesis focuses on the radiation damage effects in nanostructured Cu
via the methods of in-situ TEM (transmission electron microscope) radiation experiments, postirradiation TEM analyses, small-mechanical tests (nanoindentation and micro-pillar compression),
and computer simulations (molecular dynamics and phase-field modeling).
We design and fabricate nanostructured Cu using direct current (DC) magnetron sputtering
deposition technique, a typica physical vapor deposition (PVD) method and a bottom-up way to
construct various nanostructured metals. High-density twin boundaries (TBs) and nanovoids (NVs)
are introduced into two distinct nanostructured Cu films, including nanovoid-nanotwinned (NVNT) Cu (111) and nanovoid (NV) Cu (110). The in-situ high-energy Kr<sup>++</sup> (1 MeV) and ex-situ
low energy He<sup>+</sup>
(< 200 keV) irradiations are subsequently preformed on the as-deposited Cu
samples. On the one hand, the in-situ TEM observations suggest that TBs and NVs can influence
the formation, distribution and stability of radiation-induced defects. Meanwhile, the preexisting
microstructures also undergo structural change through void shrinkage and twin boundary
migration. On the other hand, the ex-situ micro-pillar compression tests reveal that the Heirradiated NV-NT Cu contains less defect clusters but experiences more radiation-induced
hardening. The underlying mechanisms of void shrinkage, twin boundary migration, and radiationinduced hardening are fully discussed based on post-irradiation analyses and computer simulations.
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/9033986 |
| Date | 02 August 2019 |
| Creators | Cuncai Fan (7036280) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/thesis/Radiation_Response_of_Nanostructured_Cu/9033986 |
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