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Abstract

Using density functional theory (DFT), we studied the stability of a series of low-Σ symmetrical tilt grain boundaries (STGBs) in bcc-Fe. A systematic strategy was applied to seek the most stable configuration. All STGBs studied in this work possess a similar GB energy except for the more stable Σ3(112)-GB. We present the correlations between the GB energies and local atomic structures. Based on the results from DFT calculations, we modified the recently-developed othogonal tight-binding (TB) model for iron and we show that the modified TB model is able to predict the correct GB structure and give GB energies in good agreement with DFT. We validated the model for twist GBs and apply it to study the stability of realistic models of GBs in martenstic steels.