NSUF 12-336: Stability of Interfaces Under Heavy Ion Irradiation
A fundamental understanding of interfaces is crucially important for the development of materials suitable for the extreme environments of a nuclear reactor. Interfaces play a key role in dictating the long-term stability of materials under the influence of radiation and high temperatures. Interfacial effects such as stability of interfaces under radiation at elevated temperatures, film substrate interface mixing, and evolution of defects and other phases at the interface will be investigated. Additionally, the effects of irradiation assisted oxidation in metals in the presence of interface and the effects of thin film surface modification on oxidation resistance of ferritic steels under irradiated conditions will be studied. Furthermore, the experimental work will be integrated with multi-scale computational modeling (molecular and particle dynamics codes), for gaining both theoretical and predictive capabilities to more efficiently identify the various thermodynamic and kinetic mechanisms that govern the evolution and stability of structures and phases in these film-substrate systems, and other materials systems in general. To gain a better understanding to the role of interfaces, ~500 nm thick thin films of yttrium and titanium were deposited on substrates of a Fe-12%Cr pure binary alloy. A subset of samples was irradiated at 300°C with Ni3+ ions, up to a dose of ~10 dpa. A further subset of these specimens, before the irradiation was oxidized at 700°C for 24 hours. In this turnaround experiment, the stability of the interface between the base material and the coatings after irradiation and irradiation plus oxidation will be investigated and compared with the as deposited condition using Transmission Electron Microscopy (TEM) coupled with Local Electron Atom Probe (LEAP). These techniques will be used to investigate nanometer scale physical and chemical stability of the interface between the thin films and the substrate. TEM and LEAP samples will be prepared via Focus Ion Beam techniques; the TEM samples will be analyzed at the UW-Madison facilities, while the LEAP samples will be analyzed with the LEAP 4000X HR located in the CAES facility. The whole sample preparation and sample analysis will cover a period of approximately 3 months. The proposed research cross-cuts materials degradation processes in a wide range of nuclear reactor systems that are of relevance to the DoE-NE program. Understanding the role of interfaces in materials degradation under the influence of irradiation and corrosion (oxidation) on a fundamental level is important for the development of new materials that can withstand the extreme environments of nuclear reactors. Furthermore, the deposition of thin films of materials that form highly stable oxide films can improve corrosion resistance of existing code-certified alloys. The research is of particular relevance to nanostructured oxide dispersion strengthened ferritic steels that are strengthened by (Y, Ti) oxide nanoparticles. These steels have very good high temperature mechanical properties, but the stability of the particles (largely dictated by the particle-matrix interface) is not fully understood. The findings of the study can be extended to other nano-structured alloys that are under development, such as TiC nano-particle-containing austenitic steels.
Additional Info
| Field | Value |
|---|---|
| Abstract | A fundamental understanding of interfaces is crucially important for the development of materials suitable for the extreme environments of a nuclear reactor. Interfaces play a key role in dictating the long-term stability of materials under the influence of radiation and high temperatures. Interfacial effects such as stability of interfaces under radiation at elevated temperatures, film substrate interface mixing, and evolution of defects and other phases at the interface will be investigated. Additionally, the effects of irradiation assisted oxidation in metals in the presence of interface and the effects of thin film surface modification on oxidation resistance of ferritic steels under irradiated conditions will be studied. Furthermore, the experimental work will be integrated with multi-scale computational modeling (molecular and particle dynamics codes), for gaining both theoretical and predictive capabilities to more efficiently identify the various thermodynamic and kinetic mechanisms that govern the evolution and stability of structures and phases in these film-substrate systems, and other materials systems in general. To gain a better understanding to the role of interfaces, ~500 nm thick thin films of yttrium and titanium were deposited on substrates of a Fe-12%Cr pure binary alloy. A subset of samples was irradiated at 300°C with Ni3+ ions, up to a dose of ~10 dpa. A further subset of these specimens, before the irradiation was oxidized at 700°C for 24 hours. In this turnaround experiment, the stability of the interface between the base material and the coatings after irradiation and irradiation plus oxidation will be investigated and compared with the as deposited condition using Transmission Electron Microscopy (TEM) coupled with Local Electron Atom Probe (LEAP). These techniques will be used to investigate nanometer scale physical and chemical stability of the interface between the thin films and the substrate. TEM and LEAP samples will be prepared via Focus Ion Beam techniques; the TEM samples will be analyzed at the UW-Madison facilities, while the LEAP samples will be analyzed with the LEAP 4000X HR located in the CAES facility. The whole sample preparation and sample analysis will cover a period of approximately 3 months. The proposed research cross-cuts materials degradation processes in a wide range of nuclear reactor systems that are of relevance to the DoE-NE program. Understanding the role of interfaces in materials degradation under the influence of irradiation and corrosion (oxidation) on a fundamental level is important for the development of new materials that can withstand the extreme environments of nuclear reactors. Furthermore, the deposition of thin films of materials that form highly stable oxide films can improve corrosion resistance of existing code-certified alloys. The research is of particular relevance to nanostructured oxide dispersion strengthened ferritic steels that are strengthened by (Y, Ti) oxide nanoparticles. These steels have very good high temperature mechanical properties, but the stability of the particles (largely dictated by the particle-matrix interface) is not fully understood. The findings of the study can be extended to other nano-structured alloys that are under development, such as TiC nano-particle-containing austenitic steels. |
| Award Announced Date | 2012-01-16T00:00:00 |
| Awarded Institution | None |
| Facility | None |
| Facility Tech Lead | Yaqiao Wu |
| Irradiation Facility | None |
| PI | Kumar Sridharan |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 336 |