Discovering a Strong and Ductile Mo-Nb-Ta-V-W Refractory Multi-principal Element Alloy using Surrogate-Based Optimization with Computational Data

Refractory multi-principal-element alloys (RMPEAs) are promising structural materials for advanced nuclear energy systems, yet their insufficient ambient ductility remains a major barrier to their deployment. The vast compositional space of RMPEAs offers opportunities to synergistically enhance both strength and ductility, yet simultaneously creates the demands for efficient design strategies. In this work, a surrogate-based optimization strategy was developed to discover candidate alloys in the Mo-Nb-Ta-V-W system that maximize the strength and ductility indicators from molecular statics computation. Guided by the strategy, a V-enriched and Mo/W-deficient Mo 7 Nb 15 Ta 26 V 45 W 7 RMPEA was selected from the Pareto front and fabricated. The presented RMPEA exhibited an excellent yield strength of 1.72±0.03 GPa, along with a high compressive strain of 41.7±2.1 % until catastrophic failure, surpassing most of the reported as-cast BCC RMPEAs. The remarkable strength-ductility synergy can be attributed to compositional design and the deformation compatibility of the dendritic microstructure during large compressive deformation. The proposed strategy can serve as a valuable guideline for the development of high-performance alloys with tailored mechanical properties.