Abstract
Single crystal Fe thin films (∼250 nm) were grown on MgO substrates and irradiated with 2.0 MeV Fe+ ions at 10 and 50 dpa, and the defect evolution was studied using high resolution Transmission Electron Microscopy (HR-TEM) and Doppler Broadening Positron Annihilation Spectroscopy (PAS). It was shown that irradiation induced or exacerbated a thin oxide layer at the outer interface and produced substantial Fe/Mg mixing at the film/substrate interface, particularly for the higher dose. Modeling of the PAS data allowed interpretation of the defect types at different distances from the Fe surface, and included several types of MgO substrate damage and annihilation condition changes, indicative of damage due to ballistic effects of the Fe atoms as well as chemical changes due to implantation and subsequent diffusion. This detailed PAS study compared with TEM and energy dispersive spectroscopy (EDS) provides significant insight into depth-dependent defect creation. These results will be useful for predicting defect creation in Fe-based materials under irradiation conditions, for extension to neutron irradiated structural materials.
| Original language | English |
|---|---|
| Article number | 151774 |
| Journal | Journal of Nuclear Materials |
| Volume | 526 |
| DOIs | |
| State | Published - Dec 1 2019 |
Funding
The authors would like acknowledge funding from the Department of Energy , Office of Nuclear Energy’s Nuclear Energy Enabling Technologies (NEET) program . A portion of the research was performed at Pacific Northwest National Laboratory (PNNL) , operated by Battelle Memorial Institute for the U.S. DOE under contract DE-AC05- 76RL01830 . The authors also thank Dr. Tim Droubay at PNNL for growing the Fe films and Dr. Lin Shao for his contributions to the ion beam irradiations at Texas A & M University. JSM thanks Brian Riley for commenting on the manuscript. MHW acknowledges generous funding by the Army Research Laboratory (ARL) under contract number W9113M-0075 and the tremendous support by Dr. Kelvin G. Lynn.