Thediffusionmechanismofboroninbcc-Fehasbeenstudiedbyfirst-principlescalculations.Thediffusioncoefficientsoftheinterstitialmechanism,theB–monovacancycomplexmechanism,andtheB–pacancycomplexmechanismhavebeencalculated.ThecalculateddiffusioncoefficientoftheinterstitialmechanismisD0=1.05×10-7exp（-0.75eV/kT）m2·s-1,whilethediffusioncoefficientsoftheB–monovacancyandtheB–pacancycomplexmechanismsareD1=1.22×10-6f1exp（-2.27eV/kT）m2·s-1andD2≈8.36×10-6exp（-4.81eV/kT）m2·s-1,respectively.Theresultsindicatethatthedominantdiffusionmechanisminbcc-Feistheinterstitialmechanismthroughanoctahedralinterstitialsiteinsteadofthecomplexmechanism.ThecalculateddiffusioncoefficientisinaccordancewiththereportedexperimentresultsmeasuredinFe–3%Si–Balloy（bccstructure）.Sincethenon-equilibriumsegregationofboronisbasedonthediffusionofthecomplexesassuggestedbythetheory,ourcalculationreasonablyexplainswhythenon-equilibriumsegregationofboronisnotobservedinbcc-Feinexperiments.
