Optimizing Creep Resistance in Wrought Superalloys: Effect of Small Variations in Ti and Al Content on γ′ and σ-Phase Precipitation Kinetics

Abstract The wrought CrCoNi-base C-264 superalloy exhibits a relatively low γ ′-phase volume percentage of 12.5 pct. Consequently, this alloy is malleable in the solution-treated state and can be hot and cold-rolled to obtain semi-finished products with good weldability. Subsequent precipitation-hardening establishes excellent mechanical properties, including good creep and thermomechanical fatigue resistance. Due to this combination of properties, together with good oxidation resistance and long-term phase stability, this superalloy is suitable for high-temperature applications up to 950 °C in stationary components for the aviation, automotive, and power generation sectors. To face the ever-increasing operating temperatures and more severe loading conditions, the composition of wrought superalloys has been incrementally modified, becoming relatively complex with about ten alloying elements. Each of these elements affects various properties that are challenging to predict. To further optimize these materials, it is necessary to systematically investigate the influence of small chemical changes on as many aspects as possible. This work will serve this purpose by investigating the influence of small variations in Ti and Al content ( γ ′-formers) on phase stability, precipitation kinetics of beneficial and detrimental phases, microstructure, and creep properties between 880 °C and 1000 °C using several experimental and simulation approaches. Graphical Abstract