Atomistic Simulations of Carbon Diffusion and Segregation in α-Iron Grain Boundaries

Polycrystalline materials’ mechanical properties and failure modes depend on many factors that include segregation of different alloying elements as well as its grain boundaries (GBs) structure. Understanding the parameters affecting the diffusion and binding of alloying elements within GBs will allow enhancing the mechanical properties of the commercial engineering materials and developing interface dominant materials. In practice, the coincidence site lattice (CSL) GBs are experiencing deviations from their ideal configurations. Consequently, this will change the atomic structural integrity by superposition of sub-boundary dislocation networks on the ideal CSL interfaces. For this study, ideal ∑3 GB structures and their angular deviations in BCC iron within the range of Brandon criterion will be studied comprehensively using molecular statics (MS) simulations. GB segregation energy and free surface segregation energies are calculated for carbon atoms. Rice-Wang model will be used to assess the embrittlement impact variation over the deviation angles.