Segregation of Ni and Si to coherent bcc Fe-Cu interfaces from density functional theory

摘要: The formation of Cu rich precipitates (CRPs) is known to substantially contribute to the embrittlement of reactor pressure vessel steels with high Cu contents. CRPs are commonly observed to possess a Cu core surrounded by a shell of other segregating solute species like Mn, Ni and Si. Here we calculate the segregation energies of substitutional Ni and Si to {100}, {110} and {111} orientated coherent Fe-Cu interfaces. We find Ni is strongly attracted to all orientations of coherent bcc Fe-Cu interfaces whilst Si interacts in a more complex manner, with strong attraction only to the {100} orientation. In calculating these segregation energies we also explore different methods, concluding that for this system using an external reference bulk (ERB) is optimal. By performing additional calculations we were able to decouple the elastic and chemical contributions to segregation energy finding that for Ni the chemical …