The effects of solutes on precipitated phase/matrix interface stability and their distribution tendencies between the two phases in Co-based superalloys

D0₁₉-Co₃X and μ-Co₇X₆ are two common detrimental phases in Co-based superalloys. In this work, the D0₁₉-Co₃X/γ and μ-Co₇X₆/γ interfaces were studied by density functional theory (DFT) calculation. On this basis, the influence of different solutes on the interfacial stability has been analyzed. For the D0₁₉/γ interface, Ti can lower its stability and reduce the driving force of D0₁₉’s nucleation, which is different from other elements. W, Re, and Ru can increase the interfacial stability, promoting the nucleation of D0₁₉. For μ/γ, these solutes all increase the work of separation of the interface, but compared with other solutes, Ti can hardly improve the work of separation and facilitate the nucleation of the μ phase. In addition, the solute distribution behaviors between D0₁₉ (or μ) and γ have been discussed. It is found that when solutes such as Ti are distributed in D0₁₉, the energies are all more stable than they are inside γ, and they all have the tendency to diffuse from γ to D0₁₉. For the μ and γ phases, Ti is different from other solutes since its energy to distribute in γ is more stable than that distributed in μ. During the growth of μ, the Ti inside γ has no tendency to diffuse toward μ. These results reveal the solutes’ effects on the precipitation of the D0₁₉ and μ phases at the atomic scale from the perspective of interfacial stability and atomic diffusion.