Microstructural Stability and Properties of New Nickel-Base Superalloys with Varying Aluminium: Niobium Ratio

New nickel-base superalloys with higher temperature capability are required for future, more efficient gas turbine engines. In designing such alloys, careful consideration is required of the elemental concentrations to ensure a suitable balance of properties is obtained. Herein, the phase equilibria and microstructural stability of new nickel-base superalloys with varying Al:Nb ratio are assessed via long-term thermal exposures at 700 degrees C. The alloys are analyzed using scanning and transmission electron microscopy, X-ray diffraction, differential scanning calorimetry, and Vickers hardness testing, with the results rationalized through mechanical property predictions based on strong- and weak-pair dislocation coupling mechanisms. The alloys are shown to have greater thermal stability than Inconel 718 and exhibit a pronounced hardening effect after thermal exposure. Herein, their ability for controlled age hardening and potential ease of processing is highlighted in the results.