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Understanding radiation tolerance to He in nanostructured alloys via ion irradiation


EMSL Project ID
47624

Abstract

Advanced Generation-IV fission or future fusion energy systems will require materials that are tolerant to high temperature irradiation and have good mechanical, creep, and corrosion behavior. In order to gain a scientific understanding of the fundamental mechanisms of radiation damage and radiation tolerance, a DOE Basic Energy Sciences research program is in progress. The goal of this program is to understand the behavior of nanostructured ferritic alloys (NFA), a subcategory of oxide dispersion strengthened (ODS) steels, under extreme conditions of temperature (up to 700°C) and radiation (up to 400 dpa). Previous research has shown that NFAs (MA957, 12YWT and 14YWT) have outstanding high temperature creep properties. The radiation tolerance and stability of NFAs are being studied through a combination of first-principles modeling and atomic-scale microstructural characterization. Atom probe tomography and transmission electron microscopy characterization have revealed that extremely high number densities of 1-2 nm diameter nanoclusters (NCs) of Ti, Y and O atoms form in these mechanical alloyed materials during the extrusion process. These NCs have also shown excellent microstructural stability against high dose neutron and ion irradiation and high temperatures. It is speculated that the extremely high surface area of the NCs may act as a sink for irradiation-induced point defects (vacancies, self-interstitial atoms, and transmutation-induced or fusion-produced helium) and provide improved resistance to helium bubble formation compared to other steels.
One of the primary objectives of this research program is to establish a fundamental understanding of the mechanisms that control the response of nanoclusters to intense irradiation. Mechanisms are being elucidated through a synergistic approach of ab initio theory, computer simulation and modeling and atomic level experimental characterization of nanostructured materials before and after neutron and ion irradiation by atom probe tomography and transmission electron microscopy (TEM). This basic research is ultimately aimed at developing the understanding needed to enable fundamental discoveries regarding nucleation and defect mechanisms in nanostructured materials. The scientific principles developed with this research are expected to have a broad applicability in the synthesis of new-generation nanostructured materials with high-temperature capability for use in advanced energy production and conversion systems under extreme environments.

Project Details

Project type
Exploratory Research
Start Date
2012-10-09
End Date
2013-09-30
Status
Closed

Team

Principal Investigator

Michael Miller
Institution
Oak Ridge National Laboratory

Co-Investigator(s)

Chad Parish
Institution
Oak Ridge National Laboratory

Team Members

Yanwen Zhang
Institution
Oak Ridge National Laboratory