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 $$\gamma ''$$ γ ′ ′ -phase particles with a large lattice distortion in the $$\gamma $$ γ matrix. These $$\gamma ''$$ γ ′ ′ -phase particles, however, may transform to the more thermodynamically stable $$\delta $$ δ -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 $$\gamma ''/\gamma $$ γ ′ ′ / γ coherent interfaces. By replacing an atom either in the $$\gamma ''$$ γ ′ ′ -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 $$\gamma ''$$ γ ′ ′ -phase growth are also discussed.