As a novel reactive damage material, high-entropy alloys (HEAs) have garnered widespread attention in the field of reactive damage in recent years due to their excellent mechanical properties and favorable energy release characteristics. Not only do HEAs possess high strength, high hardness, outstanding plasticity, and energy release capabilities, but their material compositions and performance parameters are also tailorable, enabling them to meet the material requirements of various application scenarios. Furthermore, HEAs have demonstrated potential application advantages in several aspects, such as processing and forming, mechanical strength, and impact-induced energy release. In particular, Ti-Zr-based systems have become a research hotspot due to their penetration-energy release coupling effect, and a growing body of experimental results has confirmed the application potential of HEAs in the field of reactive damage. Currently, reactive high-entropy alloys hold broad application prospects in areas such as projectile casings, reactive fragments, shaped charge liners, and armor-piercing projectiles. This paper introduces the definition and characteristics of reactive high-entropy alloys, summarizes existing reactive HEA systems, and reviews the current research status regarding the dynamic mechanical behavior and impact-induced energy release characteristics of reactive HEAs. It also outlines the potential application fields of HEAs and provides a preliminary outlook on the future directions of high-entropy alloys in the reactive damage domain.

With the increasing demand for enhanced mechanical properties and energy release capabilities in energetic structural materials, traditional materials struggle to concurrently achieve both high mechanical properties and energy release properties. In this study, a novel Ti_1.5ZrNbMo_0.5W_0.5 high-entropy alloy was developed by powder metallurgy process, and its microstructure, mechanical properties, damage effectiveness and energy release mechanisms were comprehensively investigated. The results indicate that the sintered Ti_1.5ZrNbMo_0.5W_0.5 alloy, characterized by high density and fine grain size, demonstrates superior quasi-static and dynamic compression properties. During the ballistic gun experiments, the Ti_1.5ZrNbMo_0.5W_0.5 alloy fragment can penetrate the Q235 steel plate with thickness of 6, 8, and 10 mm at speeds of 637, 861, and 1126 m/s, respectively. Meanwhile, after penetrating through the target, the fragment was broken into small-sized fragments and caused the severe energy release reaction. This energy release reaction is primarily driven by the substantial oxidation of Zr-rich regions, releasing significant thermal energy and successfully igniting the cotton and gasoline placed behind the steel target. This research provides a thorough characterization of the microstructure and mechanical properties of Ti_1.5ZrNbMo_0.5W_0.5 alloy. Furthermore, it evaluates its overall performance in practical armor-piercing application and reveals its energy release mechanisms. The research results provide a theoretical foundation and experimental data for the further study and application of TiZrNbMoW system high-entropy alloy.

Aluminum (Al), a commonly used reactive metals, is widely applied in reactive material systems. However, its relatively low reactivity restricts the energy release of systems. To improve the reactivity of aluminum, we introduced aluminum-cerium Al-Ce alloy containing the highly reactive rare earth element cerium into the system. The present study investigated the mechanical properties and ignition performance of four reactive material systems involving Al₂Ce/PTFE, Al/PTFE, Al₂Ce/ammonium perchlorate (AP), and Al/AP were investigated under shock overload. A split Hopkinson pressure bar (SHPB) system was used to reveal the dynamic stress-strain behavior, ignition delay, and combustion duration of the prepared samples. Thermal analysis was conducted to assess the influence of the reactive metal content on the thermal decomposition of AP. The results showed there are three distinct shock-induced ignition modes: non-ignition, combustion, and combustion (deflagration). Both Al₂Ce/PTFE and Al/PTFE exhibited substandard ignition performance. The Al₂Ce/AP system demonstrates higher ultimate strength and critical failure strain, achieving deflagration upon impact with significantly shorter ignition delay and combustion duration compared to Al/AP. The incorporation of the cerium accelerates AP decomposition and substantially increased the enthalpy of the Al₂Ce/AP system, resulting in more concentrated energy release. Ce effectively enhances the reactivity of aluminum, and its high reactivity accelerates the reaction kinetics of the reactive system. Furthermore, it significantly intensifies energy release under impact loading. In conclusion, the rare earth aluminum alloy materials exhibit a high reactivity, which demonstrates significant potential for the development of aluminum-based impact reaction materials.

Molecular dynamics simulations are used to study the dynamics of a single Al nanosphere (singlet) colliding with an aggregate of two Al nanospheres (doublet) with initial Ⅰ-shaped configuration. Depending on the initial impact velocity, there are four collision outcomes, namely bounce, adhesion, aggregation and melting. At a very low velocity, the repulsive force between the nanospheres leads the nanospheres to rebound without contact, and the critical velocity of bounce decreases with the increase of the diameter of the nanosphere. As the velocity increases, the nanospheres are sintered together due to adhesion between them and the formation of new bonds. The phase transformation and atomic diffusion during singlet-doublet collisions are quantitatively characterized by common neighbor analysis, dislocation analysis and mean square displacement to explore the underlying sintering mechanism. The critical impact velocity of singlet melting is obtained by monitoring the temperature of singlet with different diameters.

Powder compaction is the most widely used technology to fabricate polymer bonded explosives (PBX), and its parameters significantly influence the structures and mechanical properties of the final products. By conducting characterizations and experiments, this work performs a systematical study on the effects of compaction parameters. Cylindrical PBX samples are prepared with distinct fabrication parameters, including pressing rate, porosity factor, temperature and granular composition. Their initial micro-structures are obtained by scanning electron microscopy (SEM) and computer tomography (CT). The samples are tested with uniaxial compression experiments under strain rates varying from 0.0003 s⁻¹ to 7000 s⁻¹ to obtain the stress-strain responses. A rate-dependent nonlinear constitutive response model is established based on ZWT constitutive model, describing the mechanical response of the PBX samples. The recycled samples subjected to quasi-static compression are examined via SEM, and the deformation/damage mechanisms are revealed (intra-granular/inter-granular fractures and interfacial debonding). This work reveals the relations between the preparation parameters, material micro-structures and compressive properties. It provides abundant data of micro-structural characteristics and mechanical properties and proposes an efficient non-linear constitutive model for the PBX. The investigation is valuable for fabrication optimization and mechanical performance assessment of PBX.

To investigate the influence of cracks and gaps on the reaction evolution characteristics of aluminum-containing DNAN-based explosives after the formation of mechanical induced hotspots, explosive charge samples with different initial cracks were fabricated. An explosive impact ignition device based on gun propellant combustion loading was designed. The evolution process following the ignition of explosives was simulated. Pressure changes and post-test morphological features of the explosives were recorded. Numerical simulations were conducted to analyze the stress field and reaction distribution of explosive charges with different initial cracks under the same loading conditions. The results indicate that the crack-free and single-line crack explosive charge with no gap debris remained intact, and pressure dropped rapidly after the peak with no reaction occurred, and the hot spot region was located at the bottom. While for the single-line crack explosive charge with 1 mm gap, the explosive charge fractured and exhibited local low-order reactions, with a slow pressure decay process. Among these, the hot spot region of the single-line crack explosive shifted to the side surface, while the cross-line crack explosive formed dual hot spot regions on both the side surface and bottom, further enhancing the reaction intensity. This demonstrates that pre-cracks significantly influence the explosive reaction process by altering stress distribution and expanding hot spot regions.

This study focuses on the detonation performance and equation of state (EOS) of a low-density composite explosive mixed in a certain proportion of PBX-9502 powder and 502 glue. The theoretical analysis method was used based on the BKW program. The main work includes calculating the heat of formation of Kel-F (PBX-9502 binder) and ethyl cyanoacrylate (main component of 502 glue) using the group contribution method, determining the standard entropy temperature coefficient and excess volume of 18 product gases containing F and Cl elements. Within the BKW program framework, the CJ detonation velocity and pressure were determined for five mixing ratios and four density states. The corresponding JWL equation of state parameters are fitted based on the calculated CJ isentropic line. The results show that the detonation velocity and pressure are positively correlated with initial density, but negatively correlated with the content of 502 glue. The relevant results provide a theoretical basis for the selection of 502 glue ratio and mixed charge density in practical applications. The obtained JWL EOS parameters can also be used by general detonation calculation software to evaluate the detonation performance of devices. The relevant method can also be directly extended to the study of detonation parameters of other formulated explosives (sulfur, aluminum), which has important engineering application value.

To investigate the effect of boron nitride (BN) content on the explosion performance of on-site mixed emulsion explosives, the microstructure of BN-containing on-site mixed emulsion explosives were characterized by transmission electron microscopy and optical microscopy, and the thermal sensitivity, shock wave parameters, detonation velocity, and brisance of explosives were measured through steel plate tests, air explosion tests, the probe method, and lead cylinder compression tests. Combined with theoretical calculations, the influence of BN content on the microstructure, thermal sensitivity, and explosion performance of explosives was systematically studied. The test results indicate that the addition of BN does not significantly affect the stability of the internal phase droplets. At 240 ℃, the explosion delay time of the explosive samples increased from 114.28 s (blank sample) to 173.95 s (1.2% h-BN). As the mass fraction of BN increased from 0 to 1.6%, the detonation velocity, brisance, peak overpressure and specific impulse exhibited a trend of increase followed by decrease. The detonation velocity increased from 3850.45 m/s to 4724.89 m/s, and then decreased to 3903.20 m/s, with a maximum increase of 22.71%; the brisance first increased from 13.86 mm to 19.87 mm, and then decreased to 17.18 mm, with a maximum increase of 43.36%; the peak overpressure increased from 136.44 kPa to 318.33 kPa, and then decreased to 285.41 kPa, with a maximum increase of 133.31%; the specific impulse increased from 9.23 Pa·s to 33.98 Pa·s, and then decreased to 31.99 Pa·s, with a maximum increase of 268.15%. The study demonstrates that the incorporation of an appropriate amount of BN can significantly enhance the explosion performance of site-mixed emulsion explosives.

Porous ammonium nitrate is frequently used for specific applications due to its porous structure when compared with conventional ammonium nitrate, however, its higher transportation costs increase overall operational expenses. This study investigated the preparation of porous granular modified ammonium nitrate using ionic surfactant PST as an additive via spray granulation. The effects of varying PST concentrations (0−0.4%) on the pore structure, oil absorption capacity, thermal stability, and explosive properties of ammonium nitrate were examined. The research results indicate that increasing PST content gradually transforms dense ammonium nitrate particles into a porous structure with distinct interconnected pores. Thermal stability remains essentially unchanged, and the matrix chemical composition undergoes no fundamental alteration, though its adsorbed water content decreases. The modified samples exhibit enhanced binding capacity with the oil phase. The detonation velocity of the assembled charge increases from “failed to detonate normally” in the unmodified state to 2831.85 m/s. Trace amounts of PST can induce the formation of a porous structure in ammonium nitrate without significantly compromising thermal safety, while markedly improving detonation velocity performance, demonstrating potential for engineering applications.

To enhance the total output energy and power of energetic materials, plasma that generated by electrically exploded metal wires was employed to initiate the detonation of energetic materials, thereby achieving the coupled release of electrical and chemical energy. The voltage and current curves of electro-chemical coupling explosion were measured using a self-built experimental system under ambient temperature and pressure in air during the explosion process. The electro-chemical coupling explosion was divided into four typical phases: metal wire phase transition, current pause, plasma discharge, and oscillatory discharge. The research results indicate that the primary energy deposition of different metal materials occurs at different stages. Nickel and copper wires with medium boiling points and temperature coefficients of high resistance achieve efficient phase change energy deposition during the wire phase transition and current pause stages. During the plasma discharge stage, aluminum undergoes explosive vaporization due to fracture of the oxide layer. This process forms a highly conductive plasma owing to its low ionization energy, which leads to a significant leap in energy deposition. The resistance of tungsten increases sharply due to latent heat accumulation in the liquid phase, accounting for over 80% of its energy deposition during the plasma discharge stage. The study also reveals that the unique current pause phenomenon in electro-chemical coupling explosions is influenced by metal properties (such as temperature coefficient of resistance, boiling point, and latent heat of vaporization). Copper wires exhibit the longest current pause duration, while tungsten wires show no such phenomenon. This paper systematically investigates the power and energy deposition characteristics during electro-chemical coupling explosions, elucidates the influence mechanisms of metal materials on the energy release process, and provides experimental evidence and technical support for enhancing the total output energy and power of energetic materials.

To address the short comings of the Lee-Tarver ignition and growth reaction rate equation, which comprises numerous parameters (15) and is difficult to calibrate, semi-periodic trigonometric functions were introduced to optimize the model. The new reaction rate equation enhances the continuity of the ignition term, restricts the maximum value of the shape factors for the growth and completion terms to 1, mitigates the parameter compensation between the proportional coefficients and the shape factors, eliminates the reaction degree limit of the trinomial structure, reduces the number of parameters in the reaction rate equation to 10, thereby improving parameter calibration efficiency. Based on LS-DYNA, a secondary development was conducted for the improved ignition and growth model. Comparative calculations were performed to assess the shock initiation simulation results from the Lee-Tarver model and the optimized model, revealing highly consistent results for the internal pressure and reaction degree of the explosive, validating the correctness of the model development. Utilizing test data from explosive-driven metal plates, the parameters of the optimized ignition and growth model were calibrated with LS-OPT, and the sensitivity of the rate equation parameters was statistically analyzed to identify key parameters, providing a reference for further improving parameter calibration efficiency. Comparisons between test and simulated results of explosive-driven metal plates showed a simulation error of less than 3%, confirming the engineering validity of the calibrated parameters. Applying the improved ignition and growth model with safety experiments, the impact initiation response characteristics of ammunition under bullet/fragment impact were investigated. Within 66 μs after bullet impact, the peak internal pressure of the explosive reached 14.5 GPa (48.3% of the detonation pressure), indicating no detonation reaction occurred. Under fragment impact conditions, the peak internal pressure of the explosive was only 0.79 GPa, with the reaction degree near the impact point being higher than in other regions, but the maximum reaction degree was merely 0.01, confirming no detonation. The simulation results of the optimized model exhibited good consistency with test results, validating the engineering applicability of the optimized and developed ignition and growth model.