Computational Materials Design of Castable SX Ni-Based Superalloys for IGT Blade Components

To enable advanced power plant technologies (e.g. Integrated Gasification Combined Cycle) and improve the thermal efficiency of the power plant, it is desired to raising the inlet temperature of gas turbines which demands blade and vane materials exhibiting superior high temperature properties, especially creep resistance. Ni-base single crystal (SX) superalloy blades have high creep strength and are widely used in aerospace engines, but their use in industrial gas turbines (IGT) is limited primarily due to castability issues and low yield. Current techniques for developing new SX alloys are empirical in nature and are inadequate in identifying unique alloy compositions that can satisfy both the processing and property objectives. QuesTek Innovations LLC, a leader in integrated computational materials engineering, is designing a SX Ni-based superalloy that can be cast effectively as large IGT blade components, provide superior high-T creep performance comparable to state-of-the-art aeroturbine blades, thereby allowing increased thermal efficiency. During the Phase I, QuesTek successfully developed, calibrated and validated critical computation models on the liquid density and buoyancy, phase stability, and precipitate coarsening etc. These models, together with QuesTeks existing proprietary Integrated Computational Materials Engineering tools and design platform, were utilized to design a new prototype single crystal alloy, QTSX. The preliminary casting and testing results of QTSX have demonstrated advantage over 2nd Generation SX alloy ReneN5. The technical objectives of the Phase II will be to further refine QuesTeks process-structure and structure- property models (including explicit creep rate model) and optimize the design in Phase I. This stage will include on property characterization including castability, creep-rupture life, hot corrosion, etc. QuesTek anticipates generating the alloy property data needed in order to initiate a Phase III component level fabrication and qualification program. Commercial Applications and OtherBenefits: The primary future application of a QuesTek-designed alloy includes large industrial gas turbines, with potential secondary application to aerospace turbines. A new alloy providing benefits to the public including: Secure and Reliable Energy Supplies by fully realizing the clean-energy potential of abundant domestic coal supplies through increased use of IGCC, as well as permitting diverse fuel input. Clean Power Generation by reducing CO2, NOx and other gas turbine emissions to near-zero levels, in part through significantly higher combustion temperatures. Toward a Hydrogen Economy by providing a hydrogen-fueled and fuel-flexible turbine.