Innovative Design of Advanced Nb alloys for Extreme High-Temperature Applications
Dr. Jiadong Gong, Dr. James Male, Dr. Zhi Liang and Dr. Greg Olson
The aspiration to deploy Nb-based alloys as viable upgrade for Ni-based superalloys is rooted in their potential for superior performance in high-temperature applications, such as rocket nozzles and next-generation turbines. However, realizing this goal requires overcoming formidable design hurdles, including achieving high specific strength, creep resistance, fatigue and oxidation resistance at elevated temperatures, while preserving ductility at lower temperatures. Additionally, the requisite for alloy bond-coatings, to ensure compatibility with coating materials, further complicates the design process.
QuesTek Innovations has its Integrated Computational Materials Engineering (ICME) technologies to address these challenges. One of the key tasks was to delineate a strengthening strategy for the new alloy. Beyond the conventional solid solution strengthening from alloying elements in the Nb matrix, two other potent mechanisms were explored: precipitation strengthening and grain refinement through dispersion. Additionally, utilizing a statistical learning method from very limited available data, QuesTek engineers were able to identify effective materials descriptors from correlated feature spaces, enabling an accurate DBTT prediction for multicomponent Nb alloys. With the proven Materials by Design® methodology under the ICME framework, QuesTek successfully designed a novel Nb alloy that met the stringent design requirements using its advanced ICMD® materials modeling and design platform. The design process and related finding will be presented and discussed in details.