The importance of controlling grain boundary (GB) segregation is increasing, especially with the strengthening of steel nowadays. In this study, a theoretical prediction method for the amount of GB segregation for a solute element in polycrystals is established. This prediction method entails the development of a nano-polycrystalline GB model for simulating GBs in polycrystals, and the segregation energy of a solute element is comprehensively calculated for all atomic sites constituting the GB model by using an interatomic potential. From the obtained segregation energies, the segregation amount of the solute element at each atomic site is determined. Subsequently, each atomic site is classified based on its distance from the GB center and averaged to determine the segregation profile of the solute element for that distance from the GB center. By applying this method to the GB segregation of P in bcc-Fe and comparing the results with experimental findings, it is determined that this prediction method can deliver excellent prediction accuracies.

This Paper was Originally Published in Japanese in J. Japan Inst. Met. Mater. 84 (2020) 237–243.