Atomic diffusion in the Fe [0 0 1] ∑ = 5 (3 1 0) and (2 1 0) symmetric tilt grain boundary

Both the formation and diffusion activation energies of single vacancy migrating intra-layer and inter-layer near the Fe [0 0 1] Σ = 5 (3 1 0) and (2 1 0) symmetric tilt grain boundaries have been calculated by using the MAEAM and a MD method. From energy minimization, the vacancy concentration in the second layer is higher than the one in the other layers for both (3 1 0) and (2 1 0) STGBs. By the diffusion activation energies of the vacancies migrating intra-layer and inter-layer, the vacancies located from the first to the eighth layers of (3 1 0) STGB as well as the ones located from the first to the tenth layers of (2 1 0) STGB are favorably migrated to the second layer. Thus there is a vacancy aggregation tendency to the second layer near the grain boundary. For the vacancy migrating intra-layer and inter-layer, the influences of the grain boundary are respectively as far as to the fifth and eighth layers for (3 1 0) STGB as well as to the sixth and tenth layers for (2 1 0) STGB.

Research highlights
► Formation of the vacancy is preferred on 2L in Fe [0 0 1] Σ=5 (3 1 0) and (2 1 0) STGBs.
► For intra-layer migration, the diffusion activation energy in the 2L is the lowest.
► Vacancy in 1L-8L of (3 1 0) STGB and 1L-10L of (2 1 0) STGB is favorably migrated to 2L.
► Effects of the GB on vacancy migrating intra- and inter-layers are limited to 10L.