ROOM AND HIGH-TEMPERATURE MECHANICAL-BEHAVIOR OF A FE3AL-BASED ALLOY WITH ALPHA-ALPHA'' MICROSTRUCTURE

Fe-Al alloys containing slightly less than 25% Al have a two-phase mix ture of disordered and DO3-ordered phases at temperatures somewhat bel ow 550 degrees C. The microstructure of such alloys is similar to that of Ni-base gamma-gamma' superalloys, well known for their good high t emperature strength and creep resistance. Analysis of the high tempera ture strength of the two-phase Fe-Al alloys suggests that their high t emperature strength is good under conditions of slow strain rate or cr eep. Their deformation behaviour differs from that of the gamma-gamma' superalloys, however, since it is relatively easier to shear the orde red particles than to bow dislocations down channels between the parti cles. The relatively low ductility of these materials seems to be rela ted to the localization of shear by the cutting of particles rather th an to environmental sensitivity, as suggested for Fe3Al alloys. Copyri ght (C) 1997 Acta Metallurgica Inc.