No abstract

The effects of impurities of H, He, C, and N in α-Fe are investigated in terms of electronic structures using the density functional theory. Calculations reveal that H and He are stable at the T-site while C and N are stable at the O-site within α-Fe. The local strain field by H, He, C, and N in α-Fe cause structural elongation. Furthermore, the decrease of magnetic moment of Fe upon the introduction of C and N are found where the charge transfer is responsible. H, He, C, and N affect the electronic structure of α-Fe and change the fundamental physical properties of α-Fe.

The diffusion mechanism of point defects within α-Fe with a single vacancy is investigated using the density functional theory. Calculation reveals that H has a slight effect towards Fe diffusion to a vacancy. He has a strong binding with a vacancy; therefore, Fe diffusion is unlikely to happen. The diffusion of C and N from a vacancy has a high barrier. However, Fe diffusion to a vacancy decreases if the C and N diffuse from a vacancy. Thus, the effect of interstitial atoms within α-Fe with a single vacancy towards diffusion and a possible diffusion pathway is discussed.