2 - Intermetallic matrix composites based on iron aluminides

Abstract

Iron aluminide composites have a cost advantage over competing intermetallic matrix composites based on Nickel aluminides or Titanium aluminides. Further, both intermetallics of interest in Fe-Al system namely FeAl and Fe3Al exist over a wide range of compositions. Their creep resistance, modulus, strength, as well as wear resistance may be significantly enhanced by the presence of hard ceramic phase in the aluminide matrix. Oxides, borides, and carbide reinforcements have been tried to strengthen the iron aluminides. Types of reinforcements (particulate/fiber) as well as methods used for their addition are discussed. Of these carbides have shown the maximum potential. Best results have been obtained on addition of carbon rather than directly adding a carbide. Presence of carbon in the alloy may lead to savings in the processing and material costs. It also improves the machinability in ordered iron aluminides. This has been related to a reduced susceptibility of carbon containing iron aluminides to environmental embrittlement. These factors are analyzed. An assessment of progress on development of iron aluminide-based composites is presented.