# Influence of Increased TaNbV on the Microstructure, Mechanical Properties, and Energy Release Characteristics of High-Entropy Alloy HfZrTi(TaNbV)x

## TL;DR

This study introduces a new high-entropy alloy that combines strong mechanical properties with energy release under impact, offering potential for advanced energetic systems.

## Contribution

The paper proposes a novel energetic structural material by modifying a high-entropy alloy with reactive elements for energy release.

## Key findings

- Increasing TaNbV content transforms the alloy from HCP to BCC phase, improving ductility and toughness.
- The alloy releases significant chemical energy through rapid oxidation of Hf and Zr under high-rate loading.
- Adiabatic shear bands enhance energy release by inducing local thermal softening.

## Abstract

In this study, we propose a novel energetic structural material, HfZrTi(TaNbV)x (x = 0.1, 0.3, 0.5, 0.7, 0.9, Ta:Nb: V = 1:1:1), to improve the ductility and toughness of the HfZrTi high-entropy alloy (HEAs). The transformation of the single-phase Hexagonal Close-Packed (HCP) HfZrTi-based alloy into a Body-Centered Cubic (BCC) phase HfZrTiTaNbV alloy can be achieved by tuning the concentration of Group VB β-stabilizing elements. The proposed alloy combines the insensitivity and excellent mechanical strength of conventional inert alloys with the ability to react with air under high-velocity impact for energy release. The mechanical properties and energy release characteristics of HZTXx (H = Hf, Z = Zr, T = Ti, X = TaNbV) at various strain rates are systematically investigated, and comprehensive microstructural characterization is performed, establishing a clear structure–property relationship. Under high-rate loading, the rapid oxidation of reactive elements, such as Hf and Zr, with atmospheric oxygen releases substantial chemical energy, which can be further enhanced by an adiabatic temperature rise, inducing local thermal softening through adiabatic shear bands. This study elucidates the connection between the deformation response mechanism of HZTXx under dynamic loading and the microstructure, providing crucial insights for advancing the application of high-entropy alloys in energetic systems.