PROCESSING IRON-ALUMINIDE COMPOSITES CONTAINING CARBIDES OR BORIDES

Iron-aluminide composites containing 30-90 vol.% carbides or borides c an be processed to near full density (greater than 97% theoretical den sity). This wide range of ceramic contents enables the tailoring of th e composite properties to a variety of applications requiring a combin ation of the corrosion and oxidation resistance of iron aluminides and the hardness and wear resistance of the ceramic phases. The composite s are processed by conventional liquid-phase sintering of mixed powder s as well as pressureless melt infiltration. Typical mechanical proper ties such as hardness, flexure strength, and fracture toughness were e valuated for composites containing different volume fractions of carbi de or boride particulates. Furthermore, evaluations of the wear resist ance, oxidation resistance, and thermal expansion of the iron-aluminid e composites suggest many potential applications for these new materia ls.