Boron segregation to austenite grain boundary in low alloy steel measured by aberration corrected STEM–EELS

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 556; pp. 358 - 365
• Main Authors: Shigesato, Genichi, Fujishiro, Taishi, Hara, Takuya
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 30.10.2012; Elsevier
• Subjects: Aberration; Aberration corrected STEM; Austenite; Boron; Boundaries; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Defects and impurities in crystals; microstructure; Electron energy loss spectroscopy; Equations of state, phase equilibria, and phase transitions; Exact sciences and technology; Gaussian; Grain and twin boundaries; Grain boundaries; Grain boundary segregation; Inclination; Low alloy steels; Materials science; Non-equilibrium segregation; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Physics; Precipitation; Segregations; Solubility, segregation, and mixing; phase separation; Steel; Structure of solids and liquids; crystallography; Boron; Aberration corrected STEM; Non-equilibrium segregation; Grain boundary segregation; Steel; Electron energy loss spectroscopy; Grain boundaries; Crystal defects; Boundary conditions; Grain boundary precipitation; Inclination; Thickness; Electron energy loss spectra; Quantity ratio; EEL spectroscopy; Aberrations; Scanning transmission electron microscopy; Depth profiles; Principal component analysis; Concentration distribution
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2012.06.099

Boron concentration profile around prior austenite grain boundaries in Fe-0.05C–0.5Mo–0.001B (mass%) is examined by using aberration corrected STEM–EELS. Tilt series measurements of line analysis with a thin specimen (<30nm) and the principal component analysis (PCA) are performed to obtain the precise distribution of boron around the boundary. The concentration on the grain boundary reaches beyond 8at% and the distribution width is about 1.2nm. The effects of the boundary inclination and the specimen thickness are also examined by calculation based on the Gaussian broadening model. The obtained concentration profile implies that the boron segregation in the present material is formed by ‘non-equilibrium segregation mechanism’.