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Abstract:Reactive multi-principal element alloys （RMPEAs）， combining superior mechanical properties with high heat of oxidation， possess significant application potential in the field of energetic structural materials. Currently， research on the mechanical properties of these materials focuses predominantly on quasi-static compression. Data regarding tensile yield strength， which governs the structural load-bearing limit and impact-induced fragmentation and energy release characteristics， remain relatively scarce. Furthermore， due to the limited dataset size and strong non-linearity， traditional trial-and-error methods struggle to achieve precise prediction and targeted design of tensile yield strength within the vast compositional space. This study proposes a machine learning-driven design strategy to address the challenges of predicting and optimizing the tensile yield strength of RMPEAs under small-sample conditions. Based on a collected dataset of 88 as-cast RMPEAs and incorporating 33 domain-knowledge-integrated physical descriptors， prediction models were constructed using five machine learning algorithms， with a genetic algorithm employed for feature dimensionality reduction. The results demonstrate that the optimal Support Vector Regression （SVR） model achieves a coefficient of determination （R²） of 0.928 on the test set. SHapley Additive explanation （SHAP） interpretability analysis reveals that the difference in melting points of the constituent elements is the most critical factor influencing yield strength， while differences in atomic radius and electronegativity also play significant positive roles. Inverse design of the compositional space based on the model predicts that within the Ti-Zr-Nb-Ta system， increasing Ta content while reducing Nb content can significantly enhance tensile yield strength. The experimentally fabricated TiZrNbTa_x series alloys validated this trend， confirming the effectiveness and accuracy of this data-driven paradigm for the design of high-performance reactive multi-principal element energetic structural materials.

Abstract:High-entropy alloys break the design limitations of traditional metal material component systems， greatly expand the application space of metal material component lineage and performance design and engineering， and the generative model design method provides a new technical means for the design and performance prediction of high-entropy alloy systems. In this paper， a structured generative adversarial model composed of Maximum Mean Difference Variational Autoencoder（MMD-VAE） and Wasserstein Generative Adversarial Network with Gradient Penalty （WGAN-GP） is established， and three new energetic high-entropy alloy systems are generated by learning the performance parameters of three types of NbTaW energetic high-entropy alloys， and the energy density of the material system under the constraint of copper-like density is taken as the core index， and their energy density characteristics are predicted and analyzed. The results show that the accuracy of the structured generative adversarial model for the design and performance prediction of energetic high-entropy alloy systems is significantly better than that of the single MMD-VAE model algorithm， with an overall coefficient of determination of 0.7326 and a root mean square error of 0.0540， the accuracy of the generated data is balanced. This paper provides an efficient and reliable model method for the design and performance prediction of energetic high-entropy alloys of the new system.

Abstract:Slow cook-off （SCO） response assessment and formulation optimization of melt-cast explosives are challenged by the high cost of experiments and the resulting limited sample size. To address this problem， a data-driven model linking formulation composition to SCO response level was developed. Twenty-two formulations were prepared using a fixed casting process and subsequently evaluated by SCO tests under fixed conditions. The mass fractions of 12 components were used as input features， and the SCO response level was used as the class label. To alleviate minority-class scarcity and class imbalance， SMOTE-based oversampling was applied to construct a class-balanced dataset containing 32 samples for model training and evaluation. Using stratified sampling and three-fold cross-validation， ordinal logistic regression， multinomial logistic regression， random forest， and support vector machine were comparatively evaluated. Component contributions were then analyzed to improve model interpretability. Results show that non-ordinal models outperform ordinal models， and the random forest model achieves the best performance （accuracy 0.79， precision 0.78， and F₁ score 0.75）. Misclassifications occur mainly between deflagration and explosion. The feature-importance ranking is broadly consistent with engineering experience， with component IDs C， I， and K identified as dominant， followed by G， A， and H. Based on these findings， a forward formulation design framework termed “profile scanning，small-step validation， and model updating” is proposed. By visualizing the variation in predicted SCO response probabilities with component mass fraction， the framework provides decision support for candidate formulation screening and iterative validation through experiments.

Abstract:Existing numerical simulation methods cannot describe the weak-impact ignition behavior of reactive materials. Al/PTFE reactive material was selected as the research object. A model for the interface temperature rise between aluminum particles and polytetrafluoroethylene under impact loading was obtained by combining theoretical analysis and numerical simulation. This interface temperature rise model was embedded into the material point method （MPM） program framework. A numerical simulation method for the weak impact ignition characteristics of reactive materials was thus established， which is dominated by interface temperature rise. To validate the effectiveness of this method， impact ignition experiments on the reactive material were conducted using a split Hopkinson pressure bar （SHPB） apparatus. Compared with the MPM-SICR numerical simulation method that assumes a uniform temperature of the matrix and metal particles as the dominant factor for the reaction， the interface temperature rise of the reactive material under a shock wave pressure of 4 GPa is 750 ℃， which is significantly higher than the uniform temperature rise of 432 ℃. Under weak-impact conditions， the uniform temperature rise is insufficient to reach the ignition condition of the reactive material. In contrast， the interface-temperature-rise-based method can effectively simulate the deformation， fragmentation， and ignition phenomena of the reactive material. The relative error of the ignition delay time between the simulation and the experiment is 9.09%. This result demonstrates that the proposed method has high simulation accuracy for weak-impact ignition of reactive materials.

Abstract:Metal-metal energetic structural materials （ESMs） possess unique thermal reaction characteristics combined with mechanical strength， making them promising candidates for reactive fragment applications. Among them， Al-based ESMs have been extensively investigated due to their high energy-release potential. However， achieving a balance among strength， plasticity， and impact-induced energy release remains challenging， which limits their further development. In this study， Al/Zr/Bi₂O₃ ESMs with an Al/Zr molar ratio of 1.3∶1 and varying Bi₂O₃ contents were fabricated using a ball milling-spin forging process. Structural characterization， thermal analysis， quasi-static compression tests， and ballistic penetration experiments were systematically conducted. The results demonstrate that introducing an appropriate amount of Bi₂O₃ significantly enhances impact-induced chemical energy release while maintaining sufficient load-bearing capacity. Specifically， with Bi₂O₃ additions of 3% and 5%， the energy release at an impact velocity of 0.8 km·s^-1 reached 6.26 kJ·g^-1 and 7.07 kJ·g^-1， respectively， which are approximately 2.8-3.15 times higher than that of the oxidant-free Al/Zr system （2.24 kJ·g^-1）. The velocity threshold for triggering a pronounced chemical reaction in this system was approximately 0.357 km·s^-1. However， when the Bi₂O₃ content reached or exceeded 7%， severe oxidant agglomeration induced interfacial defects and material embrittlement， leading to premature fracture during impact and consequently suppressing the chemical reaction. Furthermore， the mechanisms by which Bi₂O₃ promotes Al/Zr interfacial reactions and enhances energy release were systematically analyzed. This work provides both experimental evidence and theoretical insight for the development of high-efficiency energetic structural materials through optimized oxidant content.

Abstract:To enhance the reactivity and energy release efficiency of aluminum powder fuel， ammonium perchlorate （AP）-coated micro/nano composite aluminum powder was prepared via a liquid-phase deposition-spray drying method. Scanning electron microscopy （SEM）， calorific value measurements， Hartmann tube flame propagation tests， and high-speed infrared imaging were employed to systematically investigate the effects of the AP-coated micro/nano structure on combustion performance. The results indicate that， in the uncoated system， the sample with 18% nano-aluminum exhibited the most uniform particle surface distribution， achieving a calorific value of 31.3 MJ·kg^-1. In the AP-coated system， high reactivity was maintained even at elevated nano-aluminum contents， with the 24% nano-aluminum sample exhibiting a calorific value of 27.5 MJ·kg^-1. AP coating significantly increased the flame propagation velocity and advanced the peak occurrence time； for the 18% nano-aluminum sample， the maximum flame propagation velocity increased from 62.81 to 67.50 m·s^-1. Infrared imaging results indicate that AP coating reduces the peak flame temperature and shifts the high-temperature zone from edge-enhanced to centrally concentrated.

Abstract:B@Mo composite powders with different Mo contents were prepared via mechanical alloying， thereby effectively addressing the poor processability of boron in composite solid propellants. The morphology， composition， thermal oxidation behavior， and combustion performance of the composite powders were characterized by SEM， XRD， TG-DSC and calorific value measurement. The combustion-promoting effect of Mo on boron particles and the combustion performance of NEPE propellants incorporated with B10Mo were systematically investigated. The results demonstrate that Mo exhibits a superior combustion-promoting effect on boron compared to Fe， Bi， Cr， and Ni. The B@Mo composite powders have an iron impurity content of no more than 0.6% and a median particle size （D50） ranging from 0.80 to 0.87 μm. In terms of thermal oxidation， the introduction of Mo reduces the initial oxidation temperature of boron from approximately 500 ℃ to 450 ℃， accompanied by a forward shift of the exothermic peak. The combustion heat of B10Mo is 41.02 MJ·kg^-1， corresponding to a combustion efficiency of 80.6%， which are significantly higher than that of raw boron powder （15.35 MJ·kg^-1， 27.4%）. During the combustion of B@Mo composite powders， Mo is preferentially oxidized to MoO₃， which can inhibit the formation of a dense B₂O₃ layer on the boron surface and act as an oxygen carrier to accelerate boron oxidation. The incorporation of B10Mo into the NEPE propellant formulation causes the pressure exponent to decreases from 0.76 to 0.59 within the pressure range of 10~16 MPa， and the burning rate is significantly enhanced. The findings highlight the practical application potential of boron-based fuels in regulating the combustion performance of NEPE propellants.

Abstract:To address the issue that the resin matrix of carbon fiber composites cannot participate in explosive energy release when used in warhead casings， a new type of epoxy resin curing compound with both high mechanical properties and high energy release characteristics was developed by introducing more thermally decomposable polyether segments and more easily combustible fluoropolymer-coated nano-aluminum powder into a high-rigidity epoxy resin. The curing compound was characterized by methods such as infrared spectroscopy， quasi-static mechanical testing， TG-DSC coupled testing， laser ignition testing， and closed vessel burst tests to investigate its crosslinked network structure， mechanical properties， thermal decomposition characteristics， ignition and combustion properties， and energy release characteristics. Results show that the modified epoxy exhibits a well-developed crosslinked network， with a tensile strength of 72.41 MPa and an initial decomposition temperature of approximately 273 ℃. The minimum ignition energy is reduced to 1.77 J. In addition， closed bomb tests reveal a maximum pressurization rate of 0.407 MPa·ms^-1 and a peak pressure of 5.935 MPa， indicating significantly enhanced energy-release performance.

Abstract:As a reactive alloy， the TiZrNbTa refractory high-entropy alloy exhibits excellent mechanical properties and energy release characteristics， However， due to the high melting points and significant differences among its constituent elements， the liquid–solid two-phase region is relatively wide， making it difficult to achieve large-scale forming via traditional casting processes. Powder metallurgy technology， as an effective means for preparing large-sized alloy components， offers a feasible approach to overcome this bottleneck. For this purpose， this study systematically investigates the hydrogenation and dehydrogenation processes of TiZrNbTa refractory high-entropy alloy powders. The results indicate that after hydrogenation at 550 ℃ under 0.25 MPa hydrogen pressure for 2 hs， the TiZrNbTa alloy ingot undergoes hydrogen-induced embrittlement， transforming from a Body-centered cubic （BCC） solid solution structure into metal hydrides such as ZrH₂， TiH₂， and （Nb， Ta）H. The irregular hydrogenated powder obtained via mechanical crushing has a median particle size （D₅₀） of 11.13 μm， with hydrogen and oxygen contents of 1.823% and 0.111%， respectively. Subsequently， dehydrogenation at 450 ℃ under vacuum for 1.5 hours yields TiZrNbTa refractory reactive alloy powder with a single-phase BCC solid solution structure. Its hydrogen and oxygen contents are 0.028 % and 0.121%， respectively， with a significantly narrowed particle size distribution and a reduced median particle size （D₅₀） of 5.67 μm， indicating that the hydrogenation-dehydrogenation process is an effective method for preparing TiZrNbTa refractory high-entropy alloy powder with low oxygen-contaminated and suitable particle sizes.

Abstract:To investigate the influence mechanism of particle size of Al-Li-Mg alloy on its ignition and combustion behavior， Al-Li-Mg alloys with median particle sizes of 9， 13， 16， and 24 μm was selected and tested by using of the laser particle size analyzer， scanning electron microscopy， X-ray diffractometry， simultaneous thermal analyzer， oxygen bomb calorimeter， and a laser ignition experimental setup combined with high-speed photography and fiber optic spectrometry. Results show that with the increase in particle size of the Al-Li-Mg alloy， the ignition delay time sharply decreases and then stabilizes， dropping from 135 ms to 51 ms， and further to 15 ms and 18 ms. The combustion intensity decreases from 7300.4 to 1721.6， while the combustion duration slightly prolongs and then remains largely stable from 857 ms to 928 ms，until to approximately 920 ms. A comprehensive comparison indicates that the Al-Li-Mg alloy with a particle size of 13 μm achieves a balance among ignition delay （51 ms）， combustion duration （928 ms）， and combustion intensity （6041.8）. The study reveals that particle size affects the reaction pathway of the Al-Li-Mg alloy by regulating the competitive mechanism between heat conduction efficiency and elemental diffusion. An increase in particle size limits heat conduction and promotes the migration and enrichment of Li and Mg toward the surface，which forms a temperature gradient and induces a “micro-explosion” effect， shortens the ignition delay， but reduces combustion completeness and combustion intensity.

Abstract:To investigate the reaction path evolution and energy-release mechanism of Ni/Al reactive materials under impact loading， impact-induced energy-release experiments were conducted under argon and air atmospheres. The reaction path evolution of Ni/Al reactive materials under impact loading was obtained， and the energy-release characteristics and dominant mechanisms under different paths were clarified. The results show that the energy release of Ni/Al reactive materials in air is a multi-stage process： initially triggered by the intermetallic reaction， and progressively enhanced towards oxidation with increasing velocity. Under argon atmosphere， as the velocity increases from 1005 m/s to 1617 m·s^-1， the specific chemical energy of Ni/Al reactive materials increases from 0.138 kJ·g^-1 to 0.209 kJ·g^-1， showing a linear growth trend. In contrast， under the same velocity range in air， the specific chemical energy increases significantly from 0.285 kJ·g^-1 to 1.731 kJ·g^-1， exhibiting a clear exponential growth， and is approximately 2.07 to 8.28 times higher than that in the argon atmosphere. A velocity of 1001 m·s^-1 can be regarded as the characteristic velocity at which the dominant energy-release mechanism transitions under air conditions： below this velocity， the intermetallic reaction dominates， and above this velocity， the contribution of oxidation reaction continues to increase and gradually becomes dominant. When the Ni-Al intermetallic reaction dominates， the energy-release process exhibits a transient characteristic of “rapid initiation-rapid decay”； when both the intermetallic and oxidation reactions act together， the energy-release process presents a composite characteristic of “rapid initiation-sustained combustion-slow decay.” The reaction products corresponding to different reaction paths show significant differences. Under the intermetallic reaction， Ni/Al materials undergo particle mixing， interface diffusion， and alloying processes under impact loading， forming a multiphase structure composed of NiAl intermetallic compounds， residual Ni/Al， and composition transition layers. Under the combined effect of intermetallic and oxidation reactions， the main reaction products are NiAl， Ni₃Al， NiO， and Al₂O₃. These findings reveal the reaction path evolution from the intermetallic reaction to the oxidation reaction during the impact-induced energy release of Ni/Al reactive materials， as well as its velocity dependence， providing a reference for energy-release regulation and engineering applications.

Abstract:Reactive tungsten alloys represent a class of metallic energetic structural materials featuring tungsten as a high-density framework reinforced with reactive elements such as Zr and Ti， thereby offering synergistic potential for high-strength load-bearing， kinetic penetration， and shock-induced energy release. This review systematically addresses the compositional design and fabrication methods of reactive tungsten alloys， surveys their typical microstructural characteristics and structure-property relationships， and summarizes penetration behavior and energy release characterization techniques under high-velocity impact conditions. Finally， integrating the need for composition-microstructure-property correlation， future research priorities encompass machine learning-enabled intelligent multi-objective design， development of large-scale component forming technologies with scale-up processing， and in-depth elucidation of multiscale constitutive modeling and penetration-energy release mechanisms， aiming to provide theoretical guidance for the development and engineering implementation of high-performance reactive tungsten alloys.

Abstract:Reactive damage elements integrate kinetic penetration and chemical energy release mechanisms. In order to investigate the current status and development trends of energy release characteristics of reactive damage elements under explosive loading and impact， and to comprehensively analyze research progress in reaction mechanisms， penetration-reaction coupled damage models， numerical simulation methods and dynamic loading experiments， this study elaborates on the two-stage reaction mechanisms of shock-induced and shock-assisted reactions， the thermo-mechanical-chemical coupling theory and the regulation of reaction thresholds， summarizes penetration depth and crater expansion models， after-effect overpressure and ignition/detonation models， as well as fragment cloud distribution and damage radius models. Additionally， this study outlines equations of state for reactive materials， SPH-ALE multi-physics coupling algorithms， multi-scale modeling methods， multi-physics synchronous diagnostic techniques， and the damage effect evaluation system for typical targets. On this basis， future research directions are discussed： establishing precise control methods for reactivity based on cross-scale coupling models； constructing universal damage assessment models applicable to extreme environments； and developing rapid field testing methods based on characteristic spectra and electromagnetic pulse.

Abstract:Polytetrafluoroethylene （PTFE）-based reactive materials have emerged as pivotal candidates for enhancing warhead lethality due to their high reactivity and strong post-detonation effects， garnering significant attention in the field of high-efficiency lethality. Component modification serves as a critical technique for optimizing the performance of such materials， where the introduction of various additive components can effectively regulate the mechanical strength and energy release characteristics of PTFE-based composites. This review systematically summarizes and compares research progress and functional features of modification systems， including reactive components， inert components， and metal hydrides. It focuses on elucidating the mechanisms by which metal hydrides modification systems synergistically enhance the dynamic mechanical properties and impact-induced energy release characteristics through the “decomposition-hydrogen release- in-situ reinforcement- multi-path reaction coupling”mechanism. Building upon this foundation， the review analyzes current challenges in hydride stability， process compatibility， and cost reduction， while also outlining future research directions such as the development of novel coating materials and and innovations in advanced forming technologies.