Enhancing the fragmentation with retaining a high ultimate dynamic tensile strength in the Ti-Zr-Hf-Nb-Ta energetic high-entropy alloys via interfacial precipitation

Energetic high-entropy alloys (E-HEAs) with excellent strength-ductility synergies and high energy densities have the potential to serve as structural materials in the military field. However, their energy release efficiency during the interaction with the target depends on the fracture process under impact loading, which means the service performance of E-HEAs is strongly related to their dynamic mechanical properties. In this study, we found that the dynamic tensile fragmentation behavior of the body-centered-cubic (BCC) Ti-Zr-Hf-Nb-Ta alloy can be significantly enhanced by introducing the interphase precipitates. By using this strategy, the dynamic tensile mechanical properties show a ductile-to-brittle transition as the introduction of interphase precipitates, while maintaining a high ultimate strength of about 1732 MPa. The introduced interphase precipitates can induce multiple crack initiations along grain boundaries, improving the dynamic fragmentation. Interfacial precipitates diminish intragranular local chemical order (LCO), resulting in enhanced dislocation entanglement, while simultaneously facilitating multiple intergranular crack nucleation along grain boundaries to enable efficient fragmentation. The findings offer a novel approach to enhancing the energy release efficiency of E-HEAs.