Development of iron aluminides containing carbon

Abstract

In the last decade iron aluminide composites containing carbon have been developed through ingot metallurgy routes. Work on Fe-Al alloys containing 15 to 50 atom% Al and up to 16 atom% carbon is reviewed here. 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. Carbide formation in the iron aluminide matrix results in significant improvements in strength and creep resistance. The work so far has concentrated on alloys with low (<35 atom%) Al-contents based on disordered α-phase and on Fe3Al because at Al-contents of ∼37 atom% or above graphite formation may occur in Fe-Al-C alloys. Alloys containing carbide as the major phase were found to be very brittle. The presence of carbon may limit the role of substitution alloying elements such as Cr, Mo or Ti. It may also affect hydrogen mobility in these alloys which are susceptible to hydrogen induced cracking. These factors are analysed. An assessment of the progress made in development of carbon containing iron aluminides is presented along with possible directions for future work.