Effect of carbon addition on hydrogen permeation in an Fe3Al-based intermetallic alloy

Hydrogen permeation was studied in Fe–16 wt.% Al and Fe–16 wt.% Al–1 wt.% C alloys using electrochemical permeation. Addition of 1 wt.% carbon to Fe–16 wt.% Al resulted in a significant precipitation of perovskite Fe3AlC0.5 carbide phase in the Fe3Al-based matrix. It also led to a decrease in hydrogen permeability and diffusivity by a factor of 2. However, the hydrogen solubility (trapment) did not change on carbon addition. The decrease in hydrogen permeability on carbon addition may explain the improved machinability of Fe3Al-based alloys containing carbon.