Effects of B on the Segregation Behavior of Mo at the Fe-Cr(111)/Cr2O3(0001) Interface: A First-Principles Study

The addition of B can inhibit the precipitation of sigma phases at the grain boundary to improve the hot workability and corrosion resistance for super austenitic stainless steel with high Cr and Mo content. This study focused on the interaction between B and Mo at the Fe-Cr(111)/Cr2O3(0001) interface and its effect on interfacial adhesion by employing the first-principles method, especially the effect of B on the segregation behavior of Mo. The most stable O-terminated Fe/Cr2O3 interface was chosen as the basic configuration. The segregation energy and the work of separation were calculated for the metal/chromia interface with Fe-Cr as the substrate. It has been demonstrated that B can promote the diffusion of Mo atoms into the oxide layer to increase the content of Mo in the passive film. In addition, the interfacial adhesion is higher at the most segregated sites. However, it is more difficult for two or more Mo atoms than a single Mo atom to diffuse into the oxide part with the effect of B, indicating that B can only improve the Mo content of the passive film to a small extent. The electronic properties were also further discussed to analyze the interactions and the binding characters between doped atoms and their surrounding atoms and to explain the underlying reasons for the variation of interfacial adhesion.