Aberration-corrected X-ray spectrum imaging and Fresnel contrast to differentiate nanoclusters and cavities in helium-irradiated alloy 14YWT

摘要: Helium accumulation negatively impacts structural materials used in neutron-irradiated environments, such as fission and fusion reactors. Next-generation reactors will require materials, steels, that are resistant to large neutron doses yet see service temperatures the range most affected by helium embrittlement. Previous work has indicated difficulty of experimentally differentiating nanometer-sized cavities bubbles from Ti-Y-O rich nanoclusters (NCs) radiation-tolerant nanostructured ferritic alloys (NFAs). Because NCs expected sequester away grain boundaries reduce embrittlement, experimental methods study simultaneously NC bubble populations needed. In this study, aberration-corrected scanning transmission electron microscopy (STEM) results combining high-collection-efficiency X-ray spectrum images (SIs), multivariate statistical analysis (MVSA), Fresnel-contrast bright-field STEM imaging, have been for a purpose. with careful attention TEM-STEM reciprocity, differentiates NCs. MVSA SIs unambiguously identifies Therefore, combined SI is an effective STEM-based method characterize helium-bearing NFAs.