Cyclic-oxidation of Al2O3-forming heat-resistant alloys with small amounts of sulfur and yttrium at 1373K

The cyclic-oxidation of Fe-20Cr-4Al alloys with 0.1 mass% sulfur and 0.05, 0.1 and 0.5 mass% yttrium was studied up to 5cycles (1cycle=18.0ks) in oxygen at 1373K by mass change measurements, observation of surface appearance of the alloys, X-ray diffraction, scanning electron microscopy and electron probe X-my microanalysis. Mass changes of all the alloys mostly increased with increasing number of cycles. The surface oxide of 0.1 S, 0.05 and 0.1Y alloys spalled, and that of 0.5Y alloy showed good adherence after 5cycles.