The Influence Of Si On The Primary Protection Of Lean Fecral Model Alloys In O-2 And O-2+ H2o At 600 Degrees C-A Microstructural Investigation

The present study investigates the influence of Si on the high-temperature corrosion behavior of lean FeCrAl model alloys in O-2 and O-2+H2O at 600 degrees C. The addition of Si prevented breakaway oxidation in O-2+H2O which may be explained by the increased Al-content and reduced Cr-content in the oxide (O-2) as well as the Si enrichment in the outer part of the scale (O-2+H2O). A proposed explanation for the impact of Si-addition on the Crand Al-content was given by thermodynamic calculations which showed that the presence of Si increases the activity of Al in the alloy while reducing the activity of Cr.