First principles study of interactions of oxygen–carbon–vacancy in bcc Fe

Behaviors of C or O in bcc Fe and interactions of C–O and oxygen–carbon–vacancy(O–C–□) are investigated by first principles calculations. Octahedral interstitial site is the most stable position for an O atom in bcc Fe. The migration energy of an O atom in bcc Fe is 0.46 eV. The strength of O–Fe(1 nn) bond(0.32) is slightly greater than that of Fe–Fe metallic bond(0.26). Repulsive interactions of C–C, O–O, and C–O exist in bcc Fe. When the concentration of FIA(FIA refers to C or O) is relatively high, a vacancy can attract four FIAs and form stable FIAs–□ complex.