Dissertation
Grain boundary sensitive design in Fe- and Ni-based alloys for materials response in irradiation environments
Doctor of Philosophy (Ph.D.), Drexel University
Aug 2016
DOI:
https://doi.org/10.17918/etd-7768
Abstract
Ni and Fe based fcc alloys are frequently used as critical structural materials in nuclear energy applications. However, despite extensive studies, fundamental questions remain regarding point defect migration and solute segregation to grain boundaries after high temperature irradiation and corrosion. Specifically, a systematic study on the role of grain size and grain boundary character must be completed to develop insights into new material or processing routes that have enhanced radiation tolerance, improved corrosion resistance, and thermal stability. In this dissertation, an experimental approach is used to examine the response of grain boundary character and grain size in a both model and engineering alloys under extreme environments. After severe plastic deformation and thermomechanical processing to induce a range of grain boundary types and grain sizes, heavy ion irradiation was carried out at a range of temperatures. Post-irradiation analysis of specific grain boundaries using TEM/STEM and atom probe tomography is used to examine the interaction of irradiation induced defects, defect denuded zones, and deleterious Cr solute segregation as function of grain boundary character and grain size. The results indicate variations observed in the Cr depletion and defect evolution as a function of the grain boundary plane and coherency. The ultrafine grain size indicated a grain size dependent response with reduced defect size. Overall, the work highlights the critical role for considering both the grain boundary character distribution and ultrafine grain sizes for the development of new advanced alloys for extreme environments.
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Details
- Title
- Grain boundary sensitive design in Fe- and Ni-based alloys for materials response in irradiation environments
- Creators
- Christopher Michael Barr - DU
- Contributors
- Mitra Taheri (Advisor) - Drexel University (1970-)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- xv, 193 pages
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- Materials (Science and) Engineering (Metallurgical Engineering) (1970-2026); College of Engineering (1970-2026); Drexel University
- Other Identifier
- 7768; 991014632525404721