THERMOMECHANICAL PROCESSING AND MECHANICAL CHARACTERISTICS OF PARTICLE-STRENGTHENED IRON ALUMINIDE-BASED ALLOYS

By the introduction of a fine dispersion of stable particles, a new fa mily of chromium-containing iron aluminide-based alloys, has been deve loped. These alloys exhibited modified recrystallisation kinetics, cre ep and tensile strengths and welding characteristics. The existence of a second phase dispersion reduced the tendency for localised deformat ion. Uniform deformation was promoted and ductility improved dispersoi d additions improved microstructural stability and the recrystallisati on rate was retarded by more than a factor of two. The room temperatur e tensile ductility as well as the tensile strength of the particle-mo dified alloy were increased. Furthermore, the onset of micro void coal escence occurred at lower temperatures. At 700 degrees C both alloys e xhibited similar strain rate sensitivities. Charpy impact toughness te sts showed that the ductile to brittle transition temperature for the thermomechanically treated alloys was approximately 250 degrees C and about 50 degrees C higher for the particle-containing alloy. This appa rent decrease in impact toughness was attributed to large inclusions o bserved in the cast microstructure.