Segregation at the {013} symmetrical tilt grain boundary in dilute Fe-Si alloy bicrystals

The structure and segregation behaviour of the {013} symmetrical tilt grain boundary were studied in Fe-Si dilute alloy bicrystals. Structural features such as twins, cleavage tongues and steps at the grain boundary, revealed by brittle intercrystalline fracture, are described and the identity of the fracture surface with the grain boundary is discussed. The amounts of segregation of phosphorus and silicon obtained by Auger electron spectroscopy are correlated with the structure of the analysed regions. The scatter of measured values of concentration of phosphorus and silicon in different regions of the fracture surface is explained from a structural point of view. A repulsive interaction between phosphorus and silicon atoms was confirmed. Grain-boundary enrichment ratios for phosphorus of 185 and 278, and decreases of the silicon concentration to 63 and 60% of the bulk value, were found at the grain boundary in as-grown and annealed bicrystals, respectively.