Doctoral Dissertations

Keywords and Phrases

Nanocrystalline Materials; Segregation; Atom Probe Tomography; Severe Plastic Deformation; Diffusion; High Pressure Torsion; Radiation Induced Segregation


"Nuclear reactor materials are subjected to a harsh environment including high temperatures and radiation fluences. In order to extend the lifetime of current light water reactors (LWRs) and realize the development of advanced Gen IV nuclear reactors new materials must be developed which can withstand such an environment. This thesis involves two approaches to solving this materials problem: advanced manufacturing of current commercial alloys using severe plastic deformation (SPD) and the development of new advanced high entropy alloys (HEAs).

Because SPD is effective at achieving grain refinement, this technique was used to obtain material having a high volume fraction of grain boundaries which act as effective radiation induced defect sinks. This work aims to study the pre-irradiation microstructure and irradiation tolerance of nanostructured 304 produced using SPD.

HEAs have been theorized to have retarded diffusion which prevents large voids and dislocation loops from forming in addition to their good phase stability. Most HEA compositions, however, contain Co which activates under irradiation and can cause concerns over waste management. This work studies two compositions of Co-free HEAs and evaluates their performance under ion irradiation"--Abstract, page iv.


Wen, Haiming

Committee Member(s)

Alajo, Ayodeji Babatunde
Graham, Joseph T.
Castano Giraldo, Carlos Henry
O'Malley, Ronald J.


Nuclear Engineering and Radiation Science

Degree Name

Ph. D. in Nuclear Engineering


This research was financially supported by the U.S. Department of Energy, Office of Nuclear Energy through the NEET-NSUF (Nuclear Energy Enabling Technology - Nuclear Science User Facility) program (award number DE-NE0008524), and through the NSUF-RTE program (award number 17-865).


Missouri University of Science and Technology

Publication Date

Fall 2019

Journal article titles appearing in thesis/dissertation

  • High-pressure torsion assisted segregation and precipitation in a Fe-18Cr-8Ni austenitic stainless steel
  • Enhanced resistance to irradiation-induced segregation and precipitation in a nanocrystalline Fe-18Cr-8Ni steel
  • Enhancing resistance to irradiation induced ferritic transformation through nano-structuring of austenitic steels
  • Effects of Al and Ti additions on the irradiation behavior of an Fe-Mn-Ni-Cr multi-principle element alloy


xiv, 98 pages

Note about bibliography

Includes bibliographic references.


© 2019 Andrew Kalevi Hoffman, All rights reserved.

Document Type

Dissertation - Open Access

File Type




Thesis Number

T 11627

Electronic OCLC #