Investigations of Model Fe/Y2O3 Interfaces Used to Emulate Metal/Oxide Interfaces in Oxide Dispersion Strengthen Steels
EMSL Project ID
48964
Abstract
The safe and economical operation of current and future nuclear power systems depends to a great extent on the performance of structural and fuel materials. When in service in a nuclear reactor, components are subjected to intense radiation fields, high temperatures, and corrosive environments. Operation in these extreme conditions can degrade the properties and the performance of materials, which places fundamental limitations on the temperature and radiation levels that are required for higher efficiency and improved economics. Of significant concern is the generation of helium through (n,alpha) reactions - helium bubbles can reside at grain boundaries and other interfaces in materials and can severely degrade the mechanical properties of structural steels over a wide range of temperatures.One successful approach to mitigate irradiation damage effects is to increase the fraction of internal interfaces, which act as sinks for radiation induced defects. Interfaces created at nanoscale inherently provide these large interfacial areas and can dramatically mitigate detrimental effects on the mechanical properties. Materials such as oxide dispersion strengthened (ODS) steel are therefore deemed to be among the most promising candidate materials for the claddings of new generation nuclear reactors due to the presence of a fine dispersion of Y2O3 and complex Y/Ti oxide nanoparticles (~10nm, 0.2 to 0.3 wt.%, also referred to as nanoclusters) which are effective in impeding dislocation movement and in annihilating irradiation induced defects at the oxide/matrix interfaces. Although considerable effort has been devoted to study the stability of these materials under radiation, the mechanism governing their superior radiation tolerance is not yet fully understood. For example, the crystallographic relationship of the oxide particles with the matrix may play a fundamental role in the ability of oxide nanoparticles to pin dislocation movement.
In this research we propose to develop a deeper understanding of the role of interfaces in structural materials, by irradiation of bilayered structures designed to emulate interfaces in nanostructured materials. Using the state-of-art deposition tools housed at EMSL, we plan to deposit thin films of ordered crystallites of Fe with epitaxial and non-epitaxial orientations on Y2O3. Once these systems are synthesized, in and out-of-plane orientation relationships of the metal/oxide systems will be investigated. Following this initial characterization, the samples will be brought to the University of Illinois, Urbana-Champaign where they will be irradiated with helium ions at room temperature at three different ion dose levels. A detailed high resolution transmission electron microscopy study of the irradiated samples will then be performed at the University of Wisconsin-Madison, to understand the role of interfaces in radiation resistant materials. This analysis will focus on addressing the nucleation and growth of helium bubbles in the system, their redistribution between the metal and the oxide constituents and the interaction between the interface and extended defects (bubbles, loops) as a function of the orientation relationships between the constituent layers.
Project Details
Project type
Limited Scope
Start Date
2015-06-01
End Date
2015-08-01
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members