Analysis of Fine Precipitates at Grain Boundaries in a High Purity Fe-S Alloy by Field Emission Auger Electron Spectroscopy

Auger Electron Spectroscopy (AES) is one of the common and useful methods used for the analysis of grain boundary segregation of solutes. We have applied this method by using a newly designed field emission electron gun for the small area analysis of grain boundaries in a high purity Fe-S alloy. It is found that sulfur segregates to grain boundaries and precipitates as Fe-sulfide, and that some of the precipitate particles consist of sulfide (FeS) and oxide. This result suggests that the oxide acts as the nucleus of FeS precipitation.