Computational Modeling of High Yttrium Refractory High Entropy Alloy Microstructures

Refractory high entropy alloys (RHEAs) are advanced metals made up of five or more principal elements in roughly equal amounts. The microstructural effects of alloying with yttrium as a principal element for RHEAs are currently not well understood. This project compared RHEA microstructures from literature with simulations using the High Entropy Alloy Predicting Software (HEAPS), which computes 10 screening criteria to predict the microstructure of a RHEA composition. The accuracy of HEAPS predictions was assessed by comparing them with experimentally validated microstructures found in literature. A combination of criteria was found to have a 95.8% accuracy rate, and a new criteria was developed with a 96.2% accuracy. These criteria were then used to compile a list of RHEAs with high concentrations of yttrium that form a solid solution, aiming to improve oxidation resistance at high temperatures. The list was narrowed down to ten alloys that showed promising properties for further research, which could include synthesis of these alloys and experimentally validating their structure and material properties.