Effects of Alloying on the Interface Energy of the gamma ''-Phase in Nickel-Based Superalloys

Abstract

Nickel-based superalloys of the 718 type have been extensively used in the production of engine parts which operate at high temperatures. The alloy is strengthened by the precipitation of small gamma ''-phase particles with a large lattice distortion in the gamma matrix. These gamma ''-phase particles, however, may transform to the more thermodynamically stable delta -phase. Such transformation might be mitigated by adding other alloying elements. In this work, we used density functional theory calculations at 0 K to study the influence of relevant alloying elements on the interface energy of the gamma ''/gamma coherent interfaces. By replacing an atom either in the gamma ''-phase or at the interface and calculating the corresponding interface segregation energy, we assessed the favorable replacement position of each alloying element. Implications of our results on the gamma ''-phase growth are also discussed.