Permeation was studied in Fe-16wt%Al and Fe-16Al-1wt%C alloys by using electrochemical permeation techniques. The addition of 1wt%C to Fe-16wt%Al resulted in the significant precipitation of perovskite Fe3AlC0.5 carbide phase in the Fe3Al-based matrix. It also led to a decrease in the H permeability, and diffusivity, by a factor of 2. However, the H solubility (entrapment) did not change due to C additions. The decrease in H permeability upon adding C was suggested to explain the improved machinability of Fe3Al-based alloys which contained C.

Effect of Carbon Additions on Hydrogen Permeation in an Fe3Al-Based Intermetallic Alloy. N.Parvathavarthini, U.Prakash, R.K.Dayal: Intermetallics, 2002, 10[4], 329-32