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Title: Sample Preparation Techniques for Grain Boundary Characterization of Annealed TRISO-Coated Particles

Crystallographic information about chemical vapor deposition layers of silicon carbide (SiC) is essential to understanding layer performance, especially when the layers are in non planar geometries, such as spherical. We performed electron Back Scatter Diffraction (EBSD) analysis of spherical SiC layers using a different approach to sample focus ion beam milling technique to avoid the negative impacts of traditional sample polishing and to address the need of very small samples of irradiated materials for analysis. Mechanical and chemical grinding and polishing of sample surfaces can introduce lattice strains and result in unequal removal of SiC and surrounding layers of different material due to the hardness differences of these materials. The nature of layer interfaces is thought to play a key role in performance of the SiC; therefore, analysis of representative samples at these interfacial areas is crucial. In work reported here, a focused ion beam (FIB) was employed in a novel manner to prepare a more representative sample for EBSD analysis from TRISO layers free of effects introduced by mechanical and chemical preparation methods. In addition, the difficulty of handling neutron irradiated microscopic samples such as those analyzed in this work has been simplified with pre tilted mounting stages. Ourmore » study showed that although the average grain size of samples may be similar, the grain boundary characteristics may differ significantly. It was also found that low angle grain boundaries, comprises 25% in the FIB-prepared sample vs only 1-2% in the polished sample measured in the same particle. From this study it was determined that results of FIB prepared sample will provide more repeatable results, as the role of sample preparation is eliminated.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [4] ;  [5]
  1. Idaho State Univ., Idaho Falls, ID (United States). Dept. of Nuclear Engineering and Health Physics
  2. Idaho National Lab. (INL), Idaho Falls, ID (United States). Fuel Performance and Design Dept.
  3. Idaho State Univ., Idaho Falls, ID (United States). Dept. of Nuclear Engineering and Health Physics; Idaho National Lab. (INL), Idaho Falls, ID (United States). Fuel Performance and Design Dept.
  4. Idaho National Lab. (INL), Idaho Falls, ID (United States). Fuel Fabrication and Characterization Dept.
  5. Center for Advanced Energy Studies, Idaho Falls, ID (United States); Boise State Univ., ID (United States). Dept. of Materials Science and Engineering
Publication Date:
Report Number(s):
INL/JOU-15-36781
Journal ID: ISSN 0029-5450
Grant/Contract Number:
AC07-05ID14517
Type:
Accepted Manuscript
Journal Name:
Nuclear Technology
Additional Journal Information:
Journal Volume: 196; Journal Issue: 1; Journal ID: ISSN 0029-5450
Publisher:
American Nuclear Society (ANS)
Research Org:
Idaho National Lab. (INL), Idaho Falls, ID (United States)
Sponsoring Org:
USDOE Office of Nuclear Energy (NE)
Country of Publication:
United States
Language:
English
Subject:
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS; chemical vapor deposition; Electron Back Scatter Diffraction; focused ion beam; grain boundary character; scanning electron microscopy; silicon carbide
OSTI Identifier:
1357484