Materials Modeling Tool for Alloy Design to Streamline the Development of High Temperature, High-Entropy Alloys for Advanced Propulsion Systems

The performance of gas turbine engines is greatly improved as engine operation temperatures are increased. This has dictated that the hot structural components, made of nickel-based superalloys, often operate at temperatures approaching their melting point. Alternate materials with higher temperature performance are desired for use in the hot section of gas turbine engines. Higher temperature capable metallic systems also exist with alloys based on Mo and Nb of high interest due to their high melting points, good creep properties and acceptable high temperature (>1200°C) oxidation performance in air. However, their high density and propensity to fail in a brittle manner at low temperatures is limiting as is the poor oxidation performance of Mo-based alloys at moderate temperatures (~800°C) due to the vaporization of MoO3. High entropy alloys are alloys with five or more principal elements leading to significantly higher mixing entropies than conventional alloys. This promotes the formation of solid solution phases with simple crystal structures and can result in enhanced alloy properties including enhanced high temperature strength, good structural stability, low diffusion coefficients, good creep resistance and good oxidation resistance. In this work, we explore the development of Mo-based, and optionally Nb-based, HEAs as potential high temperature structural alloys.