Minimal Variation of Defect Structure Due to the Order of Room Temperature Hydrogen Isotope Implantation and Self-Ion Ir
- PDF / 387,404 Bytes
- 6 Pages / 432 x 648 pts Page_size
- 25 Downloads / 130 Views
MINIMAL VARIATION OF DEFECT STRUCTURE DUE TO THE ORDER OF ROOM TEMPERATURE HYDROGEN ISOTOPE IMPLANTATION AND SELF-ION IRRADIATION IN NICKEL Brittany Muntifering1,2, Jianmin Qu2,3, Khalid Hattar1 1
Sandia National Laboratories, Albuquerque, NM, 87185, U.S.A. 2 Northwestern University, Evanston, IL, 60208, U.S.A. 3 Tufts University, Medford, MA, 02155, U.S.A.
ABSTRACT The formation and stability of radiation-induced defects in structural materials in reactor environments significantly effects their integrity and performance. Hydrogen, which may be present in significant quantities in future reactors, may play an important role in defect evolution. To characterize the effect of hydrogen on cascade damage evolution, in-situ TEM self-ion irradiation and deuterium implantation was performed, both sequentially and concurrently, on nickel. This paper presents preliminary results characterizing dislocation loop formation and evolution during room temperature deuterium implantation and self-ion irradiation and the consequence of the sequence of irradiation. Hydrogen isotope implantation at room temperature appears to have little or no effect on the final dislocation loop structures that result from self-ion irradiation, regardless of the sequence of irradiation. Tilting experiments emphasize the importance of precise two-beam conditions for characterizing defect size and structure. INTRODUCTION The structural materials used in fusion reactors will be exposed to high energy neutrons that result in atomic displacement cascades and transmutation reactions, which produce significant quantities of helium and hydrogen isotopes. Plasma facing materials are also exposed to high flux, low energy plasma ions including helium and hydrogen isotopes. It is generally assumed that hydrogen is not trapped very effectively at room temperature in most metals due to its high mobility and solubility [1]; however, radiation induced damage in the form of vacancies and vacancy clusters may act as hydrogen traps. Recent experimental results suggest that, in certain temperature ranges, there may be a synergistic effect of hydrogen with displacement damage and helium, which results in an increase in swelling and material hardening in comparison to displacement damage and helium alone [2]. To assist in the selection of structural materials for future nuclear reactors, and as a guide to new material development, it is critical to develop an understanding of the mechanisms involved in hydrogen enhanced materials degradation. In this study, in-situ transmission electron microscopy (TEM) self-ion irradiation and deuterium implantation was performed, both sequentially and concurrently, at room temperature on nickel. Nickel was chosen as a model face-centered cubic system to gain insight into mechanisms involved in the hydrogen-displacement cascade interplay for more complicated austenitic steels. These preliminary results suggest that hydrogen isotope implantation at room temperature has little or no effect on the final dislocation loop structures that re
Data Loading...
