The influence of Si on the primary protection of lean FeCrAl model alloys in O2 and O2+H2O at 600 °C—A microstructural investigation

Abstract

The present study investigates the influence of Si on the high-temperature corrosion behavior of lean FeCrAl model alloys in O2 and O2+H2O at 600 °C. The addition of Si prevented breakaway oxidation in O2+H2O which may be explained by the increased Al-content and reduced Cr-content in the oxide (O2) as well as the Si-enrichment in the outer part of the scale (O2+H2O). A proposed explanation for the impact of Si-addition on the Cr- and 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.

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