Explosion mechanics originated from China’s “Two Bombs and One Satellite” project and was named by Hsue-Shen Tsien in 1963. It primarily studies the occurrence patterns of explosions, as well as the utilization, control, and protection of their mechanical effects. As an interdisciplinary subject, it involves fluid mechanics, solid mechanics, physics, and chemistry. The core of this discipline lies in understanding how high-power-density energy is transmitted through shock waves and other means within an extremely short time, leading to high-speed flow, large deformation, and even the failure of media. Since its inception, explosion mechanics has made a series of significant contributions to China’s national security and defense, aerospace, advanced manufacturing, and major engineering projects. Four distinguished scientists—Che-Min Cheng (2012), Kai-Jia Cheng (2013), Ze-Shan Wang (2017), and Qi-Hu Qian (2018)—have successively won the National Highest Science and Technology Award. In recent years, this field has continued to make breakthroughs following the “Four-Extreme” strategy, focusing on energetic materials, detonation technology, impact physics, and damage and protection. Moreover, the number of researchers engaged in explosion mechanics has grown rapidly. Nevertheless, the development of explosive mechanics still faces challenges, including the need for full-chain innovation from fundamental research to engineering applications, and the paradigm shift from Galileo’s “experiments-mathematics” approach to artificial-intelligence-empowered scientific research. In this Roadmap, we aim to provide a broad overview of recent and potential future activities in explosive mechanics and to present a development roadmap by gathering contributions from scientists with diverse backgrounds. We believe that these contributions will significantly stimulate the generation of original achievements and the advancement of state-of-the-art experimental, theoretical, and numerical tools. We also hope, this Roadmap will further establish the strategic importance of explosion mechanics as both a “shield” and a “spear” for safeguarding national security, and as a “masterful hand” in solving major engineering problems.

This study investigates the effect of prefabricated holes on adiabatic shear failure (ASF) in Ti6Al4V alloy under dynamic loading. Using time-resolved X-ray imaging and finite element simulations, the role of these defects in shear localization and microvoid evolution was analyzed. The results show that defects reduce the instability strain by 2 %, accelerating shear band formation. The localized shear strain reaches 1.2, slightly lower than the theoretical value. Dynamic recrystallization (DRX) is identified as the primary mechanism driving shear localization and shear band formation. Microvoids nucleate within the shear band, potentially influenced by tensile stresses and dislocation accumulation at the grain boundaries. These findings provide insights into the microscale mechanisms of adiabatic shear failure and have implications for material design under dynamic loading.

Combustion front structure and phase transition induced fracture are central to combustion dynamics in energetic materials, yet their direct observation under high pressures has remained elusive. Here, we report the first real-time visualization of HMX single crystal combustion using fourth-generation synchrotron X-ray phase-contrast imaging, capturing the transient interplay between melting, bubbling, and cracking at micron-scale resolution. Our observations reveal a sharp pressure-driven topological transition in the picture of the combustion front: at 0.1 MPa, the classical three-phase (solid-liquid-gas) structure prevails with a thick molten layer exhibiting intense bubble dynamics; at 7.0 MPa, the melt layer thins below 1 mu m and bubbling is completely suppressed. Concurrently, the beta ->delta phase transition induced cracks shift from catastrophic fragmentation at ambient pressure to markedly slower propagation at elevated pressure, where they serve as conduits for hot gas infiltration. These findings provide decisive experimental evidence for theoretical models and establish critical constraints for multiscale modelling of HMX combustion.

Deformation twinning constitutes a critical plasticity mechanism governing material response under high pressures and high strain rates. Despite decades of research, the evolution of deformation twinning under such extreme loading conditions and its influence on macroscopic mechanical response remain poorly understood. In the current work, we establish a phase-field twinning (PFT) model for high pressure and strain rate conditions. Through coupling the PFT model with a dislocation-based crystal plasticity model under a hydrodynamic-elastic-plastic framework, the model can concurrently capture the heterogeneous twinning features induced by the shock wave, including random nucleation, growth, and detwinning, and the experimentally measured wave structures of the shock wave. Furthermore, this model provides a mesoscopic physical picture of how shock wave propagation and reflection influence the evolution of twin substructures. Specifically, a single stress wave leads to twin nucleation, while subsequent multiple reflections of the stress wave cause the nucleated twins to undergo further growth or detwinning. Apart from that, the model successfully evaluates the effect of pre-existing twins on subsequent plastic deformation, demonstrating excellent agreement with recent post-shock characterization experiments.

The thermodynamic properties of molten iron under Earth's outer core conditions are fundamental to understanding the core's structure, composition, and dynamics. However, experimental constraints under such extreme conditions remain scarce. Shock compression experiments can provide a viable means of reproducing the relevant thermodynamic regime of the outer core. Here, we report precise shock temperature measurements of molten iron up to ~364 GPa, approaching pressures at the core's center. By integrating these results with existing measurements of density and sound velocity in shock-compressed iron, we determine the thermal equation of state and compressional wave velocity (VP) of molten iron throughout outer core conditions. Compared with pure molten iron, Earth's outer core exhibits a depth-increasing density deficit and a depth-decreasing VP excess, reaching ~9.0% and ~1.3% at the inner-core boundary, respectively. Notably, the density deficit flattens while the VP excess steepens within the lowermost ~280 km of the outer core. These trends reveal a heterogeneous basal outer core, comprising a partially crystallized F-layer overlain by a gradient in light-element concentration. Our findings provide direct experimental constraints on the thermodynamic behavior of molten iron under outer core conditions, offering insights into the compositional stratification, thermal evolution, and long-term sustainability of the geodynamo.

We present time-resolved Raman spectroscopy measurements to study the structural response of β-HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine) up to 20 GPa and over compression rates ranging from 0.03 to 1.07 GPa/s using a dynamic diamond anvil cell. Similar to previous static high pressure results, two phase transitions of β→ζ and ζ→ɛ were observed at approximately 5.7 and 9.5 GPa, respectively, regardless of the compression rate. This can be attributed to the fast transition kinetics of a displacive transition mechanism. Further, when decompressed to ambient pressure, all the phase transitions are reversible and there is no chemical reaction. Our results clearly indicate that little effect of the investigated compression rates on the structural response of β-HMX, suggesting the behavior of β-HMX during manufacture, transport or handling can be molded using the existing static high pressure data, which will contribute to the prediction of the safety of β-HMX based explosives and development of kinetic initiation models.

Metal hardening is a long-standing and challenging fundamental scientific problem in solid mechanics and material sciences. Under ultrahigh pressure and ultrahigh strain rates, the dynamic yield strength (flow stress) of metals exhibits unprecedented hardening. The severe lack of understanding of defect evolution under such conditions hinders deeper insights into this extreme phenomenon. In this study, we propose a theoretical framework for quantifying the collective evolution of dislocation assemblies applicable to a wide pressure range. Based on this framework, a universal constitutive model for FCC and BCC metals in dynamic high-pressure regimes, >= 10(5) s(-1) and >= 1 GPa, is established. This model requires only one physically meaningful parameter, being the Taylor hardening coefficient, to be determined whose value range aligns perfectly with multiscale simulations, enabling quantitative reproduction of dynamic strength-pressure relationships of six typical metals across 1-400 GPa. Moreover, this work reveals the underlying mechanisms of the linear relationship between the dynamic strength and loading pressure. These findings establish fundamental laws for describing nonequilibrium material behavior under shock loading.

Modeling ultrafast plasticity remains a fundamental challenge in solid-state physics and materials science, largely due to the limited deformation information that current dynamic in situ diagnostics can provide. Over the past two decades, research on dynamic constitutive models has predominantly focused on dislocation-mediated mechanisms, while deformation twinning has often been oversimplified or treated as a single empirical stress-shear-rate relation. In this study, we propose a dynamic crystal plasticity framework that concurrently captures the evolution of both dislocation and twinning substructures. In particular, the twin fraction is not evolved through a single empirical kinetic law but is resolved at the substructure level, with twin nucleation, propagation, growth, and detwinning governed by separate kinetic equations, each tied to a distinct physical mechanism. Twinning and dislocation mechanisms are coupled through a plastic-dissipation-based energy partitioning rather than through empirical cross-hardening coefficients. Plate-impact simulations on BCC metals (tantalum and vanadium) and the HCP metal magnesium show quantitative agreement with both macroscopic shock wave profiles and post-mortem microstructural characteristics. While the formulation retains phenomenological elements (for example, the power-law form of the nucleation rate and the mean-field representation of the twin fraction), resolving the individual twinning substructures and grounding the slip-twinning coupling in an energy-partitioning framework yields clearer mechanistic insights than purely phenomenological treatments, establishing a preliminary foundation for incorporating twinning physics into high-rate constitutive models.

The strength enhancement of materials under modest loading was first documented by Bridgman, nearly a century ago. However, specific materials present anomalous strength softening at high pressures, including copper, which is a prototype fcc metal. To reveal the underlying mechanism of this anomalous phenomenon, we employed a combined Modified Williamson-Hall and Modified Warren-Averbach analytical approach to conduct a systematic and comprehensive analysis on the macroscopic to microscopic scales. The in situ crystallite size evolution, dislocation density variation, and flow stress dependence on pressure in copper is reported for the first time. Our results demonstrate an unconventional strength softening regime in copper between 3.6 and 9.5 GPa. This anomalous weakening originates from the competition between the pressure-induced reduction in dislocation density and the decrease in grain size (Hall-Petch effect). This work elucidates universal mechanisms governing strength evolution in materials under extreme loading conditions, as well as offers a protocol to determine the crystallite size evolution, dislocation density variation, and flow stress of materials as a function of pressure. (c) 2025 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International (CC BY-NC-ND) license

Understanding structural phase transitions is crucial for predicting the macroscopic behaviors of materials under shock compression. In this study, we employed in situ x-ray diffraction to investigate the crystal structures of tin along the Hugoniot. Our results demonstrate that the bct-bcc phase boundary shifts to a higher pressure under shock compression compared to static compression. This shift addresses the observed discontinuity in the relationship between shear strength and shock pressure, anchoring the dynamic bct-bcc phase boundary at 34.7 +/- 2.5 GPa. To elucidate the mechanisms behind the shift, we propose a nucleation model that emphasizes the roles of surface free energy and chemical potential difference in determining the energy barrier for nucleation and the kinetics of phase transformation. This straightforward yet generalized model accounts for hysteresis effects during compression and decompression, particularly when the chemical potential differences approach zero. Additionally, it explains how phase boundaries shift under shock compression, considering competition among various phase transformation pathways. These results underscore the critical role of phase transformation kinetics in interpreting the dynamic properties of materials under shock compression, providing insights that go beyond traditional static phase diagrams.

Over the past several decades, much research effort has been dedicated to the study of optical windows, with two primary themes emerging as key focuses. The first of these centers on investigating the optical properties of typical transparent single crystals under shock or ramp compression, which helps in the selection of appropriate optical windows for high-pressure experiments. The second involves the exploration of novel optical windows, particularly transparent polycrystalline ceramics, which not only match the shock impedance of the samples, but also preserve transparency under dynamic compression. In this study, we first integrate existing research on the evolution of optical properties in transparent single crystals and polycrystalline ceramics subjected to shock or ramp loading, proposing a mechanism that links mesoscopic damage to macroscopic optical transparency. Subsequently, through a systematic integration of experiments and computational analyses on polycrystalline transparent ceramics, we demonstrate that shock transparency can be enhanced by optimizing grain size and that shock impedance can be designed via compositional tuning. Notably, our results reveal that nano-grained MgAl2O4 ceramics exhibit outstanding optical transparency under high shock pressures, highlighting a promising strategy for designing optical windows that retain transparency under extreme dynamic loading conditions.

Understanding the interplay between the thermodynamics and kinetics of phase transition under high pressure is a current challenge in material and physical sciences. Here, we present the structural response of anatase TiO2 up to 20 GPa and over compression rates ranging from 0.03 to 3.61 GPa/s, using a piezo-driven dynamic diamond anvil cell coupled with time-resolved Raman spectroscopy. It is found that the phase evolution of anatase TiO2 follows the expected thermodynamics path (i.e., anatase-* alpha-PbO2-* baddeleyite) regardless of the applied compression rate, however, the formation conditions of high pressure phases are kinetically controlled. Both phase boundaries increase approximately linearly with the logarithm of compression rate, that seems to resolve apparent contradictions between previous high pressure results. We ascribe these to the sluggish transition kinetics of a typical reconstructive transition mechanism, and highlight that the compression rate behaves as the third dimension within a high pressure phase diagram.

The manipulation of intense shock waves to either attenuate or enhance damage has long been a key goal in the domain of impact dynamics. Effective methods for such manipulation, however, remain elusive owing to the wide spectrum and irreversible destructive nature of intense shock waves. This work proposes a novel approach for actively controlling intense shock waves in solids, inspired by the principles of optical and explosive lenses. Specifically, by designing a shock wave convex lens composed of a low-shock-impedance material embedded in a high-shock-impedance matrix, we prove the feasibility of transforming a planar shock into a spherically converging shock. This is based on oblique shock theory, according to which shock waves pass through an oblique interface and then undergo deflection. Both experimental and simulation results demonstrate that, as expected, the obtained local spherical shock wave has a wavefront that is nearly perfectly spherical and uniform in pressure. Thus, this work proves the possibility of generating spherical shock waves using plate-impact experiments and highlights the potential of further exploration of the manipulation of shock waves in solids. It also contributes an innovative perspective for both armor penetration technologies and shock wave mitigation strategies.

The structural behavior of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) under high pressure is of interest in view of its well-known insensitivity to shock initiation. While the TATB has been extensively studied under static and dynamic compression regimes, little to no attention has been paid to studies at intermediate compression timescales between these two extreme conditions. Rapid compression experiments were performed to examine the structural response of TATB up to 10 GPa and over compression rates ranging from 0.01 to 2.82 GPa s-1, using a dynamic diamond anvil cell coupled with time-resolved Raman spectroscopy. We observe a remarkable consistency in the pressure-dependent Raman shift of TATB over the investigated compression rates. Meanwhile, the pressure corresponding to the abnormal Raman modes shows little indication of compression rate dependence. These data provide new evidence and continued support for the previous conclusion that a pressure-induced conformer modification instead of a structural transition occurs around 4 GPa. Insight into the high pressure structural properties of TATB at intermediate compression timescales contributes to understanding its explosive safety, effectiveness, and the mechanisms governing shock initiation, and may also help design and synthesize new energetic materials.

Rapid compression experiments were performed to examine the compression rate-dependence of the γ→α phase boundary in cerium (Ce), using a piezo-driven dynamic diamond anvil cell (dDAC) coupled with time-resolved ruby fluorescence (i.e., pressure profile) measurements. Accompanying the pressure-induced γ→α transition, large volume collapse in Ce leads to an obvious anomaly (i.e., plateau) in the pressure profile, which provides a unique opportunity for locating the phase boundary. Based on the pressure profile analysis, the transition pressures were determined over compression rates spanning three orders of magnitude (100--102 GPa/s). Unlike other metals that high compression rates can shift their phase boundaries to higher pressures, Ce shows little impact of the compression rate on its γ→α phase boundary. However, our observations are in good agreement with recent results obtained through dDAC combined with time-resolved synchrotron x-ray diffraction. This finding confirms the distinct compression rate-dependent phase transition behavior of Ce and highlights the possibility to capturing kinetic effects of phase transition up to hundreds of GPa/s in a home-built laboratory previously only accessible with large-scale x-ray source facilities.

Cerium is regarded as one of the few metals that exhibit a first-order liquid–liquid phase transition (LLPT). However, despite the theoretical attribution of the LLPT to the localized-itinerant transition of f-electrons, there is still a lack of compelling experimental evidence to support this important scientific inquiry. In this study, we investigate the evolution of sound velocity in molten cerium along the isothermal and isobaric paths under static compression. Drawing parallels with the extensively studied γ–α isostructural phase transition, the V-shaped trend of temperature-dependent sound velocity in liquid suggests the existence of LLPT and identifies an associated mechanism predominating liquids' compressibility.

Phase change materials (PCMs) hold significant promise for thermal energy storage and management. However, challenges such as low thermal conductivity, liquid leakage, solid rigidity, and poor recyclability hinder their practical applications. Herein, a facile yet effective strategy for fabricating highly conductive, flexible, and recyclable polymer-based phase change composites (PCCs) is proposed. The physically crosslinked dual polymer networks endow the PCC film with excellent latent heat (158.6 J g-1), tunable mechanical stress (3.95-8.59 MPa), thermal-regenerating capability, and recyclability utilization. By utilizing the shear-induced alignment of graphite nanoplatelets (GNPs), the proposed PCC films demonstrate a remarkable thermal conductivity of 6.24 W m-1 K-1 at a GNP loading of 10 wt.%, achieving a thermal conductivity enhancement efficiency of 302%. Moreover, the flexible PCCs-based energy device demonstrates effective thermal regulation in electronic devices and wearable thermal management. This work provides a cost-effective avenue for the scalable fabrication of thermally conductive, flexible, and recyclable PCCs toward various thermal management applications.

In single-crystal aluminum (Al), partial dislocations are believed to play a crucial role in plasticity under extreme loading conditions; however, their activation has seldom been observed in experiments. In this work, dynamic dislocation activation of laser-shocked single-crystal Al is investigated by a combined effort of time-resolved x-ray diffraction (XRD) experiments and nonequilibrium molecular dynamics (MD) simulations. In situ XRD images of deformed single-crystal Al were captured during shock loading along the [100] and [110] orientations. MD simulations, along with calculations of slip-induced crystal plane rotation, were performed to interpret diffraction patterns. Our findings reveal that, along the [100] orientation, plastic flow is dominated by partial dislocations, whereas for the [110] orientation, flow involves both partial and full dislocations. This work thus offers unprecedented insights into the plastic mechanisms of single-crystal Al under high strain rate loading, which has never been observed in postmortem analysis or quasi-static loading.

Aluminum has been extensively studied under high-pressure and high-temperature conditions due to its role as a standard material in shock-wave experiments and its nearly free-electron s/p structure. In this study, we investigate the Hugoniot temperature and melting behavior of polycrystalline Al using a two-stage light-gas gun with time-resolved in situ shock temperature measurements, up to a pressure of 155.8(1.7) GPa and a temperature of 5394(543) K. Our measured Hugoniot temperature in the solid phase aligns with previous theoretical simulations. Shock-induced melting of Al is observed at 125 GPa, corresponding to a melting temperature of 4576(235) K. This value is broadly consistent with hydrostatic high-pressure experimental results when reasonably extrapolated. By integrating both static and dynamic experimental data, we derive the melting curve of Al up to 180 GPa using the Simon melting equation. Our results indicate that both dynamic and static experiments are actually consistent on the melting line of Al, if the thermal pressure is corrected in the latter.