Achieving prominent strength-ductility trade-off and ultrahigh specific strength in novel Ti-V-Al-Zr-Nb LRCCA via inducing HCP precipitates

Abstract

Balancing lightweight, high strength, and good ductility is a major challenge for structural metals. In this study, we applied a series of mechanical-thermal treatments to a new Ti-V-Al-Zr-Nb lightweight refractory complex concentrated alloy (LRCCA) and systematically examined its microstructure and mechanical properties. The introduction of the precipitates effectively blocks dislocation movement, causing dislocations to pile up at phase interfaces, and thus increasing alloy's strength. Meanwhile, the spacing between precipitates allows some dislocations to keep moving, which reduces stress concentration and helps maintain good ductility. By introducing these precipitates, the alloy achieves a high yield strength of 1100 MPa while still reaching ∼15 % fracture strain. This balance between strength and ductility outperforms many reported RCCAs. The precipitates also enhance work hardening and promote more uniform deformation. Our findings offer a practical way to develop lightweight, strong, and ductile alloys for advanced applications.