Sustainability-Based Selection of Materials for Refractory High Entropy Alloys

Refractory high entropy alloys (RHEAs) are considered candidate materials for high-temperature applications beyond nickel superalloys. In addition to good mechanical behavior, sustainability-related materials selection and design should be considered at an early stage of development, which will allow the application of RHEAs to expand. In this work, we present an alloy design framework for RHEAs from three different perspectives. We evaluate resource availability based on geographic concentration for refractory elements and generate a supply risk index for each element. We then evaluate material prices and price volatility for each element. We also estimated an aggregate price of select alloys and compared them to their yield strength at room and high temperatures. A proper balance of improved performance and economics is considered. Finally, we evaluated environmental, physical, and human health hazards for refractory elements and used the Green Screen^® for Safer Chemicals methodology to assign benchmark scores to each element.