A novel lightweight single-phase refractory high-entropy alloy with superior yield strength and hardness developed through data-driven design

Refractory high-entropy alloys are emerging materials currently undergoing extensive investigation for engineering applications due to their high mechanical properties and microstructural stability. Efforts have increasingly concentrated on reducing their density to get high performance with low weight; however, exploring the extensive compositional space while satisfying these criteria remains a significant challenge. In this study, a novel lightweight refractory high-entropy alloy was computationally designed through the application of artificial intelligence–based strategies in conjunction with thermodynamic calculations, followed by fabrication and experimental characterization. A non-dominated sorting genetic algorithm II (NSGA-II) was utilized, incorporating thermodynamic descriptors as constraints, with three targets—two designated as objectives and one as a constraint. The resultant design space, including the Pareto front, encompassed over 2500 compositions. These candidates were further analyzed using Calphad calculations to assess phase constitution. Subsequently, a design-of-experiments approach based on conditioned Latin hypercube sampling was employed to select representative compositions for training supervised machine learning models, including least-squares boosting, k-nearest neighbors, random forest, support vector regression, and artificial neural networks. The highest-performing model (R 2 > 0.9972) was utilized as a surrogate to predict phase constitution in solutions generated by NSGA-II, thereby guiding alloy selection. The selected composition (Ti 30 V 20 Al 30 Nb 10 Ta 10 , ρ approximately 6 g/cm 3 ) was fabricated via vacuum arc melting and microstructurally and mechanically characterized. The mechanical testing results showed a hardness of 520 HV, an elastic modulus of approximately 145 GPa, a compressive yield strength of 1630 MPa, and an ultimate compressive strength of 1831 MPa, demonstrating an exceptional ratio of density to strength. These results confirm the validity of the proposed alloy design strategy.