High-Temperature Structural Material Process for Oxidation

ABSTRACT: Isothermal and cyclic oxidation at elevated temperatures could severely limit performance of high temperature materials and components for aerospace application. With ever increasing engine operating temperatures for better fuel efficiency, oxidation and its interaction with fracture & fatigue failure is becoming an important consideration for engine designer. Under this SBIR Phase I program, QuesTek Innovations LLC, a leader in the field of computational materials design, with the support from Pratt & Whitney and NASA, proposes to determine the optimal processes and suitable surface microstructure to enhance the oxidation resistance of high temperature materials, utilizing mechanistic and microstructure-based models. The primary focus is advanced aero-engine disk materials. Mechanistic oxidation models (structure-property) combined with disk alloy process models (process-structure) will be utilized to predict the surface oxidation behavior for several surface treatment procedures and their resulting microstructure, including grain size and precipitate dispersions in Ni-base disk material. The ideal microstructure and optimal surface treatment processes will be designed based on model predictions for improved oxidation resistance at relevant operating conditions defined by our project partners. Phase II efforts will experimentally validate the model predictions and further optimize surface treatment processing conditions to achieve optimal oxidation resistance. BENEFIT: By incorporating mechanistic and microstructure-based models, a key benefit of QuesTek"s approach is to reduce empirical experimentation, resulting in significant cost and time savings over a conventional empirical approach. With further development in Phase II, optimized processing and improved oxidation resistance in Ni-base aeroturbine disk alloys will be demonstrated and verified experimentally. As stated in the support letter from Pratt & Whitney, an increase in oxidation capability benefits the F135 JSF engine by improving performance and durability. In the long term, the mechanistic nature of the models will allow the interaction of oxidation with other mechanical properties, such as fatigue crack initiation and growth, to be directly incorporated into design, enabling a broader microstructure and processing optimization to achieve a balanced performance of disk components. Furthermore, the established capabilities can be used in the future to computationally design innovative disk alloy compositions, and their corresponding surface treatments, to further improve oxidation resistance, enabling higher operating temperatures and better fuel efficiency in future aeroturbine engines.