Void formation during cyclic oxidation of oxide dispersion strengthened FeCrAl alloys

ABSTRACT

Oxide dispersion strengthened FeCrAl alloys are considered for various high-temperature applications due to their excellent mechanical properties and oxidation resistance, but void formation is a concern for component durability. Cyclic oxidation testing was conducted on alloy MA956 and PM2000 at 1100–1200ºC for durations of up to 10,000 h and the void content was determined from optical cross-sections by image analysis. At 1100ºC, 100 h cycle, the low void concentrations measured were consistent with two competing mechanisms proposed in the literature: coalescence of process-induced nano-voids and alloy sintering. At 1200ºC using 1 h cycles, the void concentration was much higher, reaching ~3% to 6% for specimens tested to breakaway oxidation. The void growth was attributed to the high oxidation rates and the annihilation of oxidation-induced vacancies at the surface of the process-induced voids.

KEYWORDS:

• Void formation
• ODS FeCrAl
• cyclic Oxidation
• H₂O
• CO₂
• image analysis

Acknowledgments

The authors would like to thank G. Garner, M Stephens, T. Lowe and T. Jordan for their help with the experimental work. They also would like to acknowledge M. Brady, J. Keiser and B.A. Pint for reviewing the manuscript. This research was sponsored by the U.S. Department of Energy, Fossil Energy Crosscutting Research Program.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Office of Fossil Energy [Crosscutting Research program].