The structure and chemistry of nanoprecipitates in an oxide dispersion strengthened (ODS) 14YWT steel were systematically investigated by means of aberration-corrected scanning transmission electron microscopy. We found that the crystal structure of the nanoprecipitates depends on the particle size, while the compositional difference is insignificant. Large nanoparticles (∼10-30 nm in diameter) have a long period NaCl-based structure including TlI-type stacking, while the small nanoparticles (<5 nm) possess the NaCl-based structure with a high density of lattice defects. The size-related structural difference between small and large nanoparticles reveals the structural origins of the unusual thermal stability of the nanoprecipitates, as well as the extraordinary mechanical properties of ODS steels.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Polymers and Plastics
- Metals and Alloys