The Bureau of Mines is conducting research on substitute materials having greater resistance to high-temperature corrosive atmospheres above 600 deg. C compared to austenitic stainless steels such as aisi 304, 316, and 310, with the goal of conserving critical metals such as cr and ni. The substitute materials are based on fe-cr-ni- al compositions. Aluminum additions to fe-cr-ni alloys significantly improve high-temperature corrosion resistance, particularly sulfidation resistance. In the alloy, devised by Bureau researchers, aluminum additions are held in the form of a second-phase precipitate, b-nial. Minor additions of ti, mn, and si improve workability. Sulfidation resistance of a 12cr-5ni-4al alloy with minor additions of ti, mn, and si alloy is four to five times greater than that of aisi 304 (18cr-8ni) and 316 (18cr-12ni) stainless steel and three times greater than that of aisi 310 (25cr- 20ni) stainless steel. Oxidation resistance is superior to that of types 304 and 316 and equivalent to that of type 310 stainless steel. Mechanical properties approach those of type 310 stainless steel.