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.