Abstract
The addition of B can inhibit the precipitation of σ 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.
Highlights
Super austenitic stainless steel, possessing the austenitic microstructure with a face-centered cubic crystal structure, has been extensively applied in harsh service conditions such as seawater, oilfields, cooling water systems, flue gases, chemical applications, and nuclear reactions [1,2,3] due to its excellent corrosion resistance
The reason for this may be that the Mo atom in the oxide layer near the interface causes a larger distortion of its adjacent atoms and it is difficult to accommodate a larger atom under compression
We investigated the interaction between B and Mo at the Fe–Cr(111)/Cr2 O3 (0001) interface through first-principles calculations
Summary
Super austenitic stainless steel, possessing the austenitic microstructure with a face-centered cubic crystal structure, has been extensively applied in harsh service conditions such as seawater, oilfields, cooling water systems, flue gases, chemical applications, and nuclear reactions [1,2,3] due to its excellent corrosion resistance. Dong et al investigated the segregation behavior of different alloying additives of the Fe/Cr2 O3 interface and their effects on the interfacial adhesive strength [15], which can provide theoretical guidance for the chemical composition design of austenitic heat-resistant stainless steels. In our previous work [17], the effect of B on the segregation of Mo at grain boundaries was studied by first-principles calculations. The effects of B on the composition of the passive film and the interfacial adhesion play a significant role in corrosion resistance. In this work, first-principles calculations were adopted to study the segregation behavior and the interfacial adhesion of the Fe–Cr/Cr2 O3 interface and to explore the reason for this from the perspective of charge interaction
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