Nickel- and cobalt-based superalloys are commonly used as turbine materials for high-temperature applications. However, their maximum operating temperature is limited to about 1100 °C. Therefore, to improve turbine efficiency, current research is focused on designing materials that can withstand higher temperatures. Niobium-based alloys can be considered as promising candidates because of their exceptional properties at elevated temperatures. The conventional approach to alloy design relies on phase diagrams and structure–property data of limited alloys and extrapolates this information into unexplored compositional space. In this work, we harness machine learning and provide an efficient design strategy for finding promising niobium-based alloy compositions with high yield and ultimate tensile strength. Unlike standard composition-based features, we use domain knowledge-based custom features and achieve higher prediction accuracy. We apply Bayesian optimization to screen out novel Nb-based quaternary and quinary alloy compositions and find these compositions have superior predicted strength over a range of temperatures. We develop a detailed design flow and include Python programming code, which could be helpful for accelerating alloy design in a limited alloy data regime.

Nickel and Cobalt based superalloys are commonly used as turbine materials for high-temperature applications. However, their maximum operating temperature is limited to about 1100oC. Therefore, to improve turbine efficiency, current research is focused on designing materials that can withstand higher temperatures. Niobium-based alloys can be considered as promising candidates because of their exceptional properties at elevated temperatures. The conventional approach to alloy design relies on phase diagrams and structure-property data of limited alloys and extrapolates this information into the unexplored compositional space. In the present work, we harness machine learning and provide a design strategy for finding an Nb-based alloy composition with optimized yield strength and ultimate tensile strength at high temperatures. We use a Bayesian optimization algorithm combined with domain knowledge-based material descriptors to find an optimal Nb-based quaternary and quinary alloy composition for the targeted value of mechanical strengths. Furthermore, we extend our study to multi-objective optimization to suggest an optimal alloy candidate by integrating yield strength and ultimate tensile strength into a single composite property. We developed a detailed design flow and python programming code, which could be helpful for accelerating alloy design in a limited alloy data regime.