Vanadium-mediated lattice distortion engineering for strength–ductility synergy in Al–Nb–Ti–Zr–V refractory multi-principal element alloys

Refractory multi-principal element alloys (RMPEAs) exhibit significant potential for applications in aerospace, nuclear energy, and petrochemical industries due to their outstanding high-temperature strength, wear resistance, radiation resistance, and thermal stability. However, achieving an optimal balance between strength and ductility through compositional design remains a critical challenge for this class of materials. In this study, a series Al 2.5 Nb 17.5 Ti 50 Zr 30- x V x ( x =0, 10, 20, 30 at.%) alloys were designed and fabricated using a combination of experimental techniques and first-principles calculations. The effects of vanadium (V) substitution for zirconium (Zr) on microstructural evolution, mechanical properties, and electronic structure were systematically studied to uncover the microscopic mechanisms by which V alters the strength-ductility balance through lattice distortion. Experimental results showed that all alloys maintained a single-phase BCC solid solution structure, with cold rolling at room temperature achieving more than 80% deformation. Appropriate V substitution for Zr modulated lattice distortion and solid solution strengthening, leading to an increase in yield strength from 633 MPa to 719 MPa, while maintaining excellent room-temperature ductility (fracture elongation > 20%). First-principles calculations confirmed that V substitution for Zr reduces lattice distortion and improves the elastic modulus of the alloys. The V-regulation strategy proposed in this work provides a theoretical foundation for the synergistic optimization of strength and ductility in RMPEAs.