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

Abstract

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 °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.