NSUF 14-460: Development of advanced crystallographic analysis techniques for localised fission product transport in irradiated SiC.
The objective of this work is to develop and apply state-of-the-art microstructural characterization techniques to aid in the elucidation of microstructural development at and below the nanometer level in irradiated materials. Specifically, the objective of this rapid experiment project for this proposal is focused on the development of crystallographic information obtained using the ASTAR analysis technique. The ASTAR technique is an automatic crystallographic indexing and orientation determination tool developed for any TEM. This rapid experiment forms part of a larger study which aim to the development, optimization and comparisons of electron backscatter diffraction (EBSD) techniques for small grained (sub-micron sized) and highly strained/deformed materials as in the case of irradiated materials. EBSD as a characterization technique, although available to researchers for many years, has not been fully utilized in the fuel material research performance predictions. SiC is one of the most difficult materials to obtain EBSD patterns - both due to the preparation challenges and the optimization of EBSD parameters due to the inherent properties of the SiC, therefore our approach to develop and compare different advanced crystallographic analysis techniques. Two major DOE (and INL) programs have recently employed EBSD to the advantage of gaining new scientific knowledge for example on fission product transport in SiC and the effect of different claddings on the deformation of the base Zircaloy -4 cladding tube. Acceptance however by the wider fuel research community as a valid performance tool will need further motivation which this study will support. Various new emerging approaches and techniques are available to consider, namely the Transmission Kikuchi Diffraction (TKD) technique (otherwise named as the t-EBSD), and the newly acquired ASTAR system on the CAES TEM. The nano-scale dimensions of fission product precipitates necessitate the higher resolution of ASTAR technique to yield more accurate information. The initial project will start with unirradiated materials following for demonstration on irradiated materials. It is foreseen that two main technical benefits will result from this part of the research work. Firstly, this work will provide detailed study on the effect of sample thickness on the ASTAR grain characteristics of unirraditated SiC The benefit of this knowledge is a single approach in FIB TEM sample preparation which will be suitable for both (S)TEM-based and SEM-based transmission- EBSD. Secondly, ASTAR as a crystallographic analysis technique will be demonstrated for irradiated materials. This will provide INL the capability to use this information in fission product transport studies, to determine the effect of grain characteristics at the location of fission product transport. This ASTAR work will be internationally the first application of this technique to irradiated SiC. This work will confirm INL’s leadership in the unique combination of experimental studies that provide input to enhance future modeling capabilities. These techniques will be instrumental in fission product transport studies in fuel. Additionally, the results obtained from this project, may act as a catalyst for other applications (e.g. corrosion/degradation of SiC by specific fission products, etc.), deformed fuel cladding in the study of irradiated nuclear fuel. It is foreseen that four main technical benefits will result from this research work. Firstly, this will provide INL the capability to obtain grain boundary information for the study of fission product transport. This knowledge can be transferred to other applications and programs, for example it can be used to determine the effect of grain characteristics of composite materials on other physical properties like heat conductivity, which will become very important for the new generation accident tolerant clad designs now under discussion. Secondly, this work will provide detailed study on the effect of sample thickness on the crystallographic data generated by ASTAR on SiC The benefit of this knowledge is to develop an optimum, single approach to FIB TEM sample preparation which will be suitable for both (S)TEM-based compositional and orientation mapping on a nanometer scale. This will generate new data not previously available, internationally. Thirdlyly, the proposed work will demonstrate an alternative to SEM-based EBSD to obtain grain characteristics for SiC (and SiC-CMC materials with much higher spatial resolution. These materials are some of the most difficult materials to obtain SEM-based EBSD patterns - both due to the preparation challenges, even with FIB, and the optimization of EBSD parameters due to the inherent properties of the SiC. Fourthly, this proposed work, as part of the larger project, can be compared with crystallographic information obtained using TKD. This may provide the scientific community in future a scientific comparison between two alternative techniques.
Additional Info
| Field | Value |
|---|---|
| Abstract | The objective of this work is to develop and apply state-of-the-art microstructural characterization techniques to aid in the elucidation of microstructural development at and below the nanometer level in irradiated materials. Specifically, the objective of this rapid experiment project for this proposal is focused on the development of crystallographic information obtained using the ASTAR analysis technique. The ASTAR technique is an automatic crystallographic indexing and orientation determination tool developed for any TEM. This rapid experiment forms part of a larger study which aim to the development, optimization and comparisons of electron backscatter diffraction (EBSD) techniques for small grained (sub-micron sized) and highly strained/deformed materials as in the case of irradiated materials. EBSD as a characterization technique, although available to researchers for many years, has not been fully utilized in the fuel material research performance predictions. SiC is one of the most difficult materials to obtain EBSD patterns - both due to the preparation challenges and the optimization of EBSD parameters due to the inherent properties of the SiC, therefore our approach to develop and compare different advanced crystallographic analysis techniques. Two major DOE (and INL) programs have recently employed EBSD to the advantage of gaining new scientific knowledge for example on fission product transport in SiC and the effect of different claddings on the deformation of the base Zircaloy -4 cladding tube. Acceptance however by the wider fuel research community as a valid performance tool will need further motivation which this study will support. Various new emerging approaches and techniques are available to consider, namely the Transmission Kikuchi Diffraction (TKD) technique (otherwise named as the t-EBSD), and the newly acquired ASTAR system on the CAES TEM. The nano-scale dimensions of fission product precipitates necessitate the higher resolution of ASTAR technique to yield more accurate information. The initial project will start with unirradiated materials following for demonstration on irradiated materials. It is foreseen that two main technical benefits will result from this part of the research work. Firstly, this work will provide detailed study on the effect of sample thickness on the ASTAR grain characteristics of unirraditated SiC The benefit of this knowledge is a single approach in FIB TEM sample preparation which will be suitable for both (S)TEM-based and SEM-based transmission- EBSD. Secondly, ASTAR as a crystallographic analysis technique will be demonstrated for irradiated materials. This will provide INL the capability to use this information in fission product transport studies, to determine the effect of grain characteristics at the location of fission product transport. This ASTAR work will be internationally the first application of this technique to irradiated SiC. This work will confirm INL’s leadership in the unique combination of experimental studies that provide input to enhance future modeling capabilities. These techniques will be instrumental in fission product transport studies in fuel. Additionally, the results obtained from this project, may act as a catalyst for other applications (e.g. corrosion/degradation of SiC by specific fission products, etc.), deformed fuel cladding in the study of irradiated nuclear fuel. It is foreseen that four main technical benefits will result from this research work. Firstly, this will provide INL the capability to obtain grain boundary information for the study of fission product transport. This knowledge can be transferred to other applications and programs, for example it can be used to determine the effect of grain characteristics of composite materials on other physical properties like heat conductivity, which will become very important for the new generation accident tolerant clad designs now under discussion. Secondly, this work will provide detailed study on the effect of sample thickness on the crystallographic data generated by ASTAR on SiC The benefit of this knowledge is to develop an optimum, single approach to FIB TEM sample preparation which will be suitable for both (S)TEM-based compositional and orientation mapping on a nanometer scale. This will generate new data not previously available, internationally. Thirdlyly, the proposed work will demonstrate an alternative to SEM-based EBSD to obtain grain characteristics for SiC (and SiC-CMC materials with much higher spatial resolution. These materials are some of the most difficult materials to obtain SEM-based EBSD patterns - both due to the preparation challenges, even with FIB, and the optimization of EBSD parameters due to the inherent properties of the SiC. Fourthly, this proposed work, as part of the larger project, can be compared with crystallographic information obtained using TKD. This may provide the scientific community in future a scientific comparison between two alternative techniques. |
| Award Announced Date | 2014-01-09T00:00:00 |
| Awarded Institution | Center for Advanced Energy Studies |
| Facility | Microscopy and Characterization Suite |
| Facility Tech Lead | Yaqiao Wu |
| Irradiation Facility | None |
| PI | Isabella van Rooyen |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 460 |