Local chemical ordering enhances simultaneously strength and ductility of Ti-V-Zr-Nb-Al lightweight multi-component alloys

Abstract

Refractory multi-component alloys display superior mechanical properties at elevated temperatures. However, their brittleness at ambient temperatures, combined with challenging processability, high density, and cost-effectiveness, has hindered their widespread application in engineering. In this work, two types of Ti60(V2Zr3Nb2)40(A0) and Ti60(V2Zr3Nb2)34Al6(A6) multi-component alloys with a single Body-Centered Cubic (BCC) structure, were designed based on phase formation principles. These alloys were then manufactured using a combination of vacuum arc melting, cold rolling, and heat treatment processes. It is noteworthy that the A6 alloy present excellent processibility, achieving a 409 % elongation with a 90 % reduction in thickness, and its theoretical density decreased from 5.50 g/cm3 to 5.24 g/cm3 compared to the A0 alloy. Meanwhile, tensile tests revealed that the A6 alloy exhibited a simultaneous increase in yield strength and ductility by 10.3 % and 17.5 %, respectively, when compared to the A0 alloy. The enhanced mechanical properties were mainly attributed to the presence of Local Chemical Ordering (LCO), which was clearly observed in the undeformed sample via transmission electron microscope. Notably, the LCO was significantly influenced by deformation, and no obvious LCO was observed in the deformed alloy. The underline mechanism between LCO and dislocation was also explored. This work provides a strategy for developing novel lightweight refractory multi-component alloys with high-strength-ductility, good processibility and cost-effective.

Keywords

• Multi-component alloy
• Mechanical properties
• Deformation mechanism
• Processibility
• Local chemical ordering