Impact initiated chemical energy release of TiZr-based reactive high-entropy alloy

Abstract

Reactive structural materials, combining the outstanding mechanical properties and significant chemical energy-release characteristic, have a wide range of critical applications in the defense and energy fields. However, it remains challenging to achieve a synergy between high mechanical strength over 1 GPa and outstanding chemical energy release of reactive structural materials upon impact. Here, a novel TiZrHfNbAl reactive high-entropy alloy (R-HEA) possessing a monolithically body-centered cubic structure was synthesized with remarkable dynamic strength (∼1120 MPa) and superior energy-release performance [∼0.33 MPa assessed via vented chamber calorimetry in direct ballistic tests]. Utilizing high-speed photography, we developed a new method based on image processing to ascertain the characteristic time of energy release. After ballistic tests, the reaction products were collected and scrutinized. It was found that an increase in impact velocity resulted in a greater fraction of smaller fragments, signifying a thoroughly complete reaction. Utilization of x-ray diffractometers, along with energy-dispersive analysis, we facilitated the detection of fragments of varied sizes at differing velocities. The outcomes suggested that the energy-release pathway of TiZrHfNbAl R-HEA primarily revolved around redox reaction and intermetallic reactions, particularly, with a unique mechanism of micro-explosion.