Room and high temperature mechanical behaviour of a Fe3Al-based alloy with α-α″ microstructure

Abstract

FeAl alloys containing slightly less than 25% Al have a two-phase mixture of disordered and DO3-ordered phases at temperatures somewhat below 550°C. The microstructure of such alloys is similar to that of Ni-base γ-γ′ superalloys, well known for their good high temperature strength and creep resistance. Analysis of the high temperature strength of the two-phase FeAl alloys suggests that their high temperature strength is good under conditions of slow strain rate or creep. Their deformation behaviour differs from that of the γ-γ′ superalloys, however, since it is relatively easier to shear the ordered particles than to bow dislocations down channels between the particles. The relatively low ductility of these materials seems to be related to the localization of shear by the cutting of particles rather than to environmental sensitivity, as suggested for Fe3Al alloys.