Effects of B on the segregation of Mo at the Fe-Cr-NiΣ5(210) grain boundary

The precipitation of the σ phase at the grain boundary (GB) has an important effect on the properties of super austenitic stainless steel. This study used density functional theory (DFT) calculations to assess the segregation of Mo and B atoms at the GB and their effects on GB strength. The results demonstrated that Mo and B atoms tend to converge to grain boundary positions and B atoms are easier to segregate than Mo atoms. In addition, B can restrain the segregation of Mo to grain boundary positions, making it difficult for the positions to form an σ phase. An analysis of the inhibitory effect of different contents of B on Mo indicated that higher B content is better for restraining Mo segregation to grain boundary sites. These results are beneficial for improving the shortcomings of super austenitic stainless steel. B can also increase the GB strength while inhibiting the segregation of Mo to grain boundary sites and a charge density analysis demonstrated the results.