A novel reactive high-entropy alloy with ultra-strong strain-rate effect

Abstract

Reactive structural materials are crucial for energy exploitation and defense applications due to their outstanding energy release characteristics. However, traditional reactive structural materials often struggle to meet the required mechanical properties. In contrast, reactive high-entropy alloys that balance mechanical performance and energy release characteristics show great potential in this field. Here, we designed the active high-entropy alloy Ti₅₀Zr₂₅Hf_12.5Nb_12.5, at% using a metastable high-entropy alloy design strategy (“d-electron alloy” strategy). The alloy exhibits a single-phase BCC structure both before and after quasi-static tension, but undergoes an impact-induced ω phase transition during dynamic tension, resulting in an unprecedented increase in yield strength from 751 MPa to 1577 MPa (an increase of 110 %). Microstructural characterization revealed that the high-density dislocation walls resulting from the ω phase transition contribute to the significant strain-rate effect of the alloy. Furthermore, direct ballistic tests demonstrated that this novel active high-entropy alloy possesses excellent energy release characteristics (∼0.27 MPa assessed via Vented Chamber Calorimetry in 996 m/s direct ballistic test). This work sheds new light on designing reactive high entropy alloy with high dynamic strength may provide a mean to develop a wide range of advanced reactive structural materials.