Microstructure Evolution of Fe-Al-Si and Ti-Al-Si Alloys during High-Temperature Oxidation

Abstract:

Alloys based on TiAl and FeAl aluminides are modern materials for high-temperature applications in automotive or aerospace industry due to low density combined with good high-temperature mechanical properties and oxidation resistance. Previous works proved that the addition of silicon to these alloys improves the oxidation resistance as well as the thermal stability. In this work, the mechanism of the silicon effect was investigated by observing the microstructure of the oxide layer and the near-surface area of the Ti-Al-Si and Fe-Al-Si alloys prepared by reactive sintering powder metallurgy. It was found that silicon improves the compactness of the oxide layers. The oxide layers on Fe-Al-Si alloys are formed by Al₂O₃ and small amount of iron oxide (Fe₂O₃) while Ti-Al-Si alloys cover by TiO₂ and Al₂O₃ during the oxidation. Due to aluminium depletion of the alloy, a layer of silicides is formed under the oxide layer, thus acting as the additional protection against high-temperature oxidation.

• Periodical: Materials Science Forum (Volume 782)
• Pages: 353-358
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.782.353
• Online since: April 2014
• Authors: Pavel Novák*, Jan Kříž, Alena Michalcová, Dalibor Vojtech
• Keywords: Aluminide, Oxidation, Powder metallurgy, Silicide

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