NASA KY EPSCoR RIDG-25-006: Thermodynamic Modeling of Nanoscale Multi-Principal Element Alloys for High-Temperature Applications

Abstract The objective of this one-year Research Infrastructure Development Grant (RIDG) project is to unravel the energetic characteristics contributing to the free energy of nanoscale multi-principal element alloys (MPEAs) at elevated temperatures. In the aerospace industry, jet engines and turbine components operate at combustion temperatures exceeding 1,500°C, requiring materials that can endure high mechanical loads while exhibiting long-term creep resistance to maintain performance and reliability. MPEAs, with their unique microstructural characteristics and exceptional mechanical resilience, are promising candidates for the next generation of high- temperature aerospace materials. Their significant configurational entropy provides unparalleled freedom in atomic-level design, offering a vast array of possible alloy combinations. However, the development of MPEAs is constrained by slow data generation across the vast alloy composition and local concentration space. Optimizing MPEAs for high-temperature applications also presents a complex challenge due to the intricate interplay of thermodynamic factors. To address these challenges, we will develop an equilibrium thermodynamic model to efficiently characterize the contributions of vibrational entropy, configurational entropy, and thermalized interatomic potentials to the free energy across various compositions and temperatures. This model will be based on the Maximum-Entropy principle, which enables the relaxation of the crystal structure under different atomic configurations and finite temperatures. Our focus will be on CrCoNi-based alloys, which have demonstrated exceptional potential for high-temperature jet engine applications. The model will further incorporate the effects of local chemical concentration fluctuations and short-range ordering, both of which play a critical role in determining the strength and plastic deformation behavior of MPEAs under extreme conditions. The results of this project will demonstrate how leveraging equilibrium thermodynamic models can accelerate the discovery and design of revolutionary materials for high-temperature environments. 1