Environmental embrittlement of intermetallic compounds in Fe-Al alloys

摘要

First, it is proposed that hydrogen atoms occupy the interstitial sites in Fe_3Al and FeAl. Then the environmental embrittlement of intermetallic compounds in Fe-Al alloys is studied in the light of calculated valence electron structures and bond energy of Fe_3Al and FeAl containing hydrogen atoms. From the analyses it is found that the states of metal atoms will change, in which more lattice electrons will become covalent electrons to bond with hydrogen atoms when the atomic hydrogen diffuses into the intermetallic compounds in Fe-Al alloys, which will result in the decrease of local metallicity in Fe_3Al and FeAl. Meanwhile, it is found that the crystal will easily cleave since solute hydrogen bonds with metal atoms and severely anisotropic bonds form. As a conclusion, these factors result in the environmental embrittlement of Fe_3Al and FeAl.