In recent years, the development of rapid loading techniques (such as dynamic diamond anvil cell, dDAC) and time-resolved detection technologies based on diamond anvil presses has opened up new research directions in high-pressure science. This involves exploring the evolution of material structures and physical properties under pressure (or over time) in high-pressure non-equilibrium physical processes that lie between static high-pressure and shock-wave experiments in terms of time scale and loading rate. By reviewing and summarizing the rapid loading and time-resolved probe techniques that have emerged in recent years, this paper attempts to think about and generalize high-pressure science issues and technical challenges on the microsecond to second time scale. It starts from aspects such as structure phase transition dynamics that depend on loading rate, phase transition pathways, the formation of metastable phases, microstructures, and mechanoluminescence, aiming to provide some inspiration and reference for researchers in this field.

High pressure phase transition is one of the core concerns in the field of condensed matter physics, Earth and planetary science and material science. And the loading strain rate is an important influencing factor for the kinetics of phase transition. Due to the lack of in situ diagnostics of crystal structure under dynamic loading, and the limited experimental research on the phase transition behavior over a wide range of strain rates, there is no unified physical model to describe how the phase transition dynamics evolve from static compression to high strain rate shock compression. Since the high-pressure phase diagram of silicon is extremely rich and possesses a large number of substable phases, and at the same time, the kinetic factors play a crucial role in the high-pressure phase transition process of silicon, silicon is an ideal material for studying the high-pressure phase transition kinetics, which is of great significance for the theoretical modeling of universal phase-transition kinetic processes. Here, we take silicon as an example and present its phase transition behavior under quasi-static, medium strain rate and high strain rate loading in turn, highlighting the effect of loading strain rate on its high-pressure phase transition behavior.

Exploring the influence of size effect on the physical properties of materials under high pressure is helpful for the development of new materials with novel or improved properties. The static compression behaviors of polycrystalline tungsten powder with average grain sizes of 30 and 65 nm under high pressure were studied by using diamond anvil cell (DAC) combined with synchrotron radiation X-ray diffraction respectively. By analyzing the peak position and the half-height width of the X-ray diffraction spectrum at each pressure, the unit cell volume, grain size, and microscopic strain of nano-tungsten metal under high pressure were obtained. By fitting the third Birch-Murnaghan equation, the bulk moduli of 30 and 65 nm tungsten are obtained to be 257(7) GPa and 343(8) GPa, respectively. Combined with the results of previous studies, it is found that when the gain size decreases from micron to 10 nm, the yield strength of tungsten at 10 nm increases by 3.5 times compared with that of microcrystal samples; the bulk modulus shows a tendency of increasing firstly and then decreasing, and the bulk elastic modulus of tungsten at 30 nm decreases by 25% compared with that of tungsten at 65 nm.

High-strength steels are widely employed due to their excellent combination of high strength, good ductility, and corrosion resistance. However, they often exhibit significant strain rate sensitivity. In this study, two types of high-strength steels, Ultrafort 401 and Ferrium S53 steels, were investigated. Tensile tests were conducted at varying strain rates (10⁻⁴−10³ s⁻¹), to obtain the yield strength, the tensile strength, the uniform elongation, the hardening index and other performance parameters. The variations of these parameters with strain rate were thoroughly analyzed. It was observed that under different strain rates, Ferrium S53 steel consistently outperformed Ultrafort 401 steel in terms of tensile properties, while they exhibited different trends. As the strain rate increased, both of the yield strength and the tensile strength of Ultrafort 401 steels increased, while for Ferrium S53 steels the yield strength of increased, and the tensile strength decreased and then increased. Combined with the microstructure analysis, it is found that the higher yield strength of Ferrium S53 steel was related to the smaller grain sizes, while the different tensile strength trends of the two high-strength steels with the increase of strain rate were associated with differences in strain hardening response. With the increase of strain rate, the dimple size of Ultrafort 401 steels increases, whereas it decreases and then increases for Ferrium S53 steels. This indicates a different pattern of change in the strain hardening level of the two high-strength steels with increasing strain rate. The findings in this work provide a scientific basis for assessing the mechanical performance of high-strength steels under various loading conditions and hold significant implications for their engineering applications.

Magnesium is widely used for materials science, aerospace, and military equipment. It is found that the mechanical property of magnesium under deformation loading is closely related to discontinuous dynamic recrystallization. In this work, we construct a dynamic recrystallization phenomenological model of magnesium alloy via phase-field methods. We choose AZ31B magnesium alloy as the research object and simulate grains and grain boundaries evolutions during dynamic recrystallization under 0.01–1.00 s⁻¹ and 250–400 ℃. Iterative solving methods of stress-strain curves and recrystallization evolutions are improved by introducing plastic deformation energy to phase-field model. The simulation results show the volume fraction of recrystallization grains and the average grain size of samples increase with the rise of temperature and decrease of strain rates.

In this study, molecular dynamics method was used to simulate the deformation and spallation behavior of [100] single crystal aluminum under the action of equivalent ramp waves and square waves. Accordingly, the correlation between loading waveform and spallation behavior was analyzed. The results showed that the synergistic effect of the pulse shape transition and the thermodynamic path affected the material spallation. The nucleation of non-uniform holes dominated by defects was not the decisive factor affecting the spallation strength of materials. The difference of spallation characteristics of materials under different loading waveforms was mainly determined by the difference of temperature rise under different thermodynamic paths, which led to uniform spallation at maximum velocity of 3.00 km/s, but the spall strength of ramp wave group was 56.6% higher than that of square wave group. Due to the gradual compression and slight temperature softening effect, the ramp wave loading made the material presented milder damage than the impact loading, which became more significant with the increase of loading speed.

The energy caused by atomic level shear in a crystal is called generalized fault energy (GSFE), This is an important material property for describing nanoscale plastic phenomena in crystalline materials, such as dislocation decomposition, nucleation, and twinning. During the shock loading process, the elastoplastic transition occurs after one-dimensional elastic strain, so the generalized stacking fault energy is of great significance in understanding the occurrence of plastic flow. Here, we calculate the generalized GSFE surface of glide (111) surface of silicon and diamond under uniaxial strain in [111] direction by using the first principles of density functional theory. Based on the translation symmetry of GSFE surface, we fit the GSFE surface expression obtained by Fourier series expansion and the generalized stacking fault energy curves for the $ [{\overline{1}10}] $ (111) and $ [ 11\overline{2}]$ (111) directions are given. With the increase of strain, the intrinsic fault energy (γ_I) and the unstable fault energy (γ_us) have obvious changes, and the ratio of the unstable stacking fault energy to the intrinsic stacking fault energy (γ_us/γ_I) decreases indicating that dislocations in crystals are not easily decomposed under uniaxial strain in the $ \left\langle{111}\right\rangle $ direction. This result explains the results of dynamic experiments of dislocation evolution at four generations of light sources that the speed and strength of fault signals loaded along $ \left\langle{111}\right\rangle $ direction are much lower than those loaded along $ \left\langle{110}\right\rangle $ direction and $ \left\langle{100}\right\rangle $ direction.

Using statistical physical model, the equation of state of UH₃ crystal and its chemical decomposition products were constructed in this paper. The phase diagram of UH₃ at high temperature and high pressure was obtained by Gibbs free energy comparison, and the shock compression properties of UH₃ with different initial densities were investigated. The results show that the chemical decomposition of UH₃ crystals occurs at about 74.0 GPa under isothermal compression. Increasing the temperature promotes the chemical decomposition, but the influence of pressure on the chemical decomposition of UH₃ is non-monotonic. Solid UH₃ decomposes at 35–50 GPa under shock compression, and the chemical decomposition process is accompanied by obvious volume collapse, therefore, the Hugoniot of UH₃ decomposition products lies below the isotherm, which is an abnormal phenomenon in comparison with ordinary metals or compounds. Moreover, the decomposition pressure of UH₃ decreases with the increase of initial porosity. When the initial porosity is about 1.5, the decomposition products of UH₃ are more difficult to compress than UH₃ in crystal phase, thus showing a phenomenon similar to the abnormal expansion of large porosity materials under shock compression. These results enrich our understanding of dynamical compression behavior of UH₃, and can serve as theoretical basis for further research on physical and chemical properties of actinide metal hydrides at high temperature and high pressure.

Polymers are widely used in various fields of national defense and national economy. They are inevitably exposed to extreme conditions of high temperature and high pressure during applying. Thus, it is necessary to study their physical properties and “phase transition” under impact loading. Because of their characteristic molecular chain structure, polymers show different properties from most materials such as metals. The intercept extrapolated from Hugoniot curve at low pressure is obviously higher than their body sound velocity at atmospheric pressure. The wave profile at low pressure presents a structure with an arc shape. At 20–30 GPa, the Hugoniot line turns obviously, indicating that the material has undergone a “phase transition” under impact loading. The “phase transition” is explained as chemical decomposition or lattice structure transformation, and the kinetics of “phase transition” is studied. In addition, the modeling method of equation of state based on chemical decomposition is briefly introduced. Finally, the prospect is put forward according to the doubtful points in the study of physical properties and “phase transition” of polymers under impact loading.

For energetic materials, the lattice vibration modes in the 6 THz (200 cm⁻¹) range are very sensitive to structural changes caused by external temperature and pressure changes. Therefore, mid- and far-infrared vibrational spectroscopy can be used as a powerful tool to study high-pressure phase transitions in these materials. We have obtained high-pressure vibrational spectra of hydrazine nitrate, using mid- and far-infrared ultra-broadband spectroscopy, whose broadband was generated by air plasma, combined with a diamond anvil cell (DAC). The crystal structure of hydrazine nitrate, as well as the infrared spectrum, were calculated by using the first principle method. Based on the calculation, the intermolecular interactions were analyzed. Combined with the experimental results, it was revealed that the structural changes under pressure alter the strength of intermolecular hydrogen bonds and van der Waals interactions, which in turn affects the low-frequency vibrational modes. And by analyzing the vibrational spectra, we observed the phase transition process of hydrazine nitrate.

High pressure neutron diffractometer (HPND), also known as FENGHUANG, at China Mianyang Research Reactor’s (CMRR) neutron science platform, which include neutron focusing system, detector system, high-pressure devices and integrated system, can be constructed to in situ neutron diffraction experiments under ambient, high/low temperature, and high-pressure conditions. For in situ high-pressure neutron diffraction experiments, the pressure can reach to over 30 GPa at room temperature, and 10 GPa at 2000 K. FENGHUANG diffractometer has been widely applied in the field of materials researches, to provide precise information on atomic occupation, magnetic structure, crystalline structure and phase transitions, such as transition-metal nitrides, Li-containing materials, magnetic materials, energetic materials, ferroelectric ceramics.

In the large-volume press (LVP), the pressure calibration for the sample chamber is generally carried out by using phase transitions of specific materials with resistance changes. But there are no suitable materials for pressure calibration in the range of 22.5−34.5 GPa. As we know, the mineral 50 mol%MgSiO₃-50 mol%Al₂O₃ (En₅₀Cor₅₀) systems in deep earth undergo structural transition to perovskite phase under high pressure and high temperature (HPHT) conditions. Moreover, the content of Al₂O₃ dissolved in perovskite MgSiO₃ increases gradually with raised pressure above 27 GPa. Therefore, En₅₀Cor₅₀ was selected as the pressure calibration material for further calibrating 28 GPa in the LVP in this study, and this is an indirect pressure calibration method. First, the low-pressure calibration curve (6.0−22.5 GPa) of system oil pressure versus chamber pressure was obtained by using the phase transitions of different pressure calibration materials. Then, based on the low-pressure calibration curve and previous research results En₅₀Cor₅₀, the estimated system oil pressure corresponding to the 28 GPa of chamber pressure is 65 MPa. At the estimated oil pressure, the En₅₀Cor₅₀ samples were heated to 2000 K and maintained for 3−7 h. The results of X-ray diffraction, Raman, and electron probe measurements indicate that bridgmanite has been successfully synthesized, and the dissolved Al₂O₃ molar fraction is greater than 13.7%. According to the previous research results, the corresponding sample chamber pressure is about 29 GPa. This method successfully calibrated the sample chamber pressure around 28 GPa in the LVP, which fill in the blanks for calibrating this pressure range.

Under the conditions of high temperature and high pressure, a series of materials transform into superionic states, which fall between the solid and liquid states and are widely believed to exist in the interior of Earth and exoplanets. Computational research has found that under the temperature and pressure of the Earth’s inner core, iron-hydrogen, iron-carbon, and iron-oxygen alloys transform to superionic states, manifested as elements such as hydrogen, carbon, and oxygen flowing rapidly like liquids in solid iron alloys. The flowing light elements cause softening of Fe alloys and a decrease in seismic wave velocities, explaining the characteristics of core density deficient and low shear wave velocity observed in geophysics. The superionic iron-hydrogen alloy in the core can interact with the geomagnetic field, forming a lattice preferred orientation fiber driven by a dipole geomagnetic field, explaining the origin of the anisotropic structure in the inner core. The discovery of superionic iron-light-element alloys in the inner core has updated our understanding of the state of the inner core, and is of great significance for understanding the structure, composition, and evolution of Earth’s inner core, as well as the relationship between the inner core structure and the Earth’s magnetic field.

An electrochemical accelerated corrosion test was conducted on the Q245R steel sample to simulate the actual corrosion conditions of the carbonization kettle. It was found that corrosion not only causes changes in geometric dimensions, but also causes degradation of the material’s mechanical properties. Tensile tests were conducted on Q235R steel materials at different temperatures, corrosion rates, and strain rates (low strain rate of 10⁻³−1 s⁻¹, medium strain rate of 10−10² s⁻¹, and high strain rate of 10³ s⁻¹). A fitting method was carried out based on the modified Johnson-Cook constitutive equation and MATLAB software, which provides the relationship between its characteristic strength, heat treatment temperature and corrosion rate. According to the results, it can be seen that the fitting curve is in good agreement with the experimental curve.

The 3D printing manufacturing process and mechanical behaviors of “carbon fiber-graphene” (CF-G) reinforced thermoplastic polyurethane (TPU) composites were investigated. The CF-G reinforced TPU composite filaments were prepared by the screw extrusion process, then the G+CF/TPU composites were manufactured by the fused deposition modeling (FDM) technology and microwave post-treatment process. It shows that the CF-G heterostructure can synergistically enhance the mechanical properties of TPU composites. Especially, by adopting the novel microwave post-treatment process, the G+CF/TPU specimens exhibited the further improved tensile strength and toughness, which may be attributed to the promoted interface bonding between the reinforcing phase and matrix, and the reduced internal defects between points, layers, and channels induced by the synergistic effect between the CF-G heterostructure and microwave. This study has positive significance for exploring the mechanical reinforcement and post-treatment processes of 3D printed materials.

Based on the LS-DYNA three-dimensional numerical modeling method and the modified Kong-Fang concrete material model, the numerical investigation on damage and failure of ultra-high performance concrete (UHPC) targets subjected to dislocation multi-attacks was carried considering the two-dimensional normal distribution of strike points. The numerical model and material models along with the corresponding parameters were firstly validated by comparing the numerical simulation results of the UHPC targets subjected to projectile penetration followed by explosion to the corresponding test data. Then numerical simulation of the damage and failure in UHPC targets under the multi-attacks by a typical warhead were conducted with 10 groups different circular error probable (CEP) to discuss the effects of the CEP and strike times on the damage and penetration depth. The numerical results demonstrate that the damage evolution caused by the subsequent projectile penetration and explosion continues to develop along the damage area caused by the first projectile penetration. The penetration depth gradually increases as the number of strike increases. The penetration depth calculated with explosion is larger than that calculated without explosion when the CEP is same during multi-attacks. When CEP is equal to 3 m and 1 m, the relative penetration depth is about 1.2 and 1.7, respectively. In other words, the relative penetration depth increased with decreasing of the CEP. The research conclusion shows that the design method of shielding layer thickness in the existing protective design code is dangerous subjected to multi-attacks.

In order to investigate the effect of HMX content on the impact sensitivity and non-shock initiation reaction characteristics of PBT based propellants, BAM impact sensitivity tests, friability tests and Susan tests were carried out. The experimental results show that with the increase of HMX content, the characteristic drop height of PBT based propellants at 50% explosion probability (H₅₀) decreases, indicating that the impact sensitivity increases with higher HMX content. In friability tests, the critical non-shock initiation velocities for the PBT based propellants with the HMX mass fraction of 0, 5%, 10%, and 15% are 168, 147, 136, and 131 m/s, respectively, showing a decline in the critical non-shock initiation velocity as HMX content rises. In Susan tests, four different kinds of PBT based propellants react as explosion or partial detonation at velocities range of 120 m/s to 300 m/s. The PBT based propellant with the HMX mass fraction of 10% exhibits more intense reactions compared to the other three PBT based propellants at the same velocity.

As highly efficient absorbing and dissipating materials, porous materials were widely used in the study of detonation wave attenuation. In order to further explore the mechanism of explosion suppression by porous materials, the effects of typical flexible (sponge) and rigid (wire mesh) porous materials on the detonation cellular structure for hydrogen and oxygen mixture were investigated systematically. The effects of thickness and porosity of sponge and wire mesh on the structure and size of detonation cell were discussed in detail. The cellular pattern of detonation wave was recorded by using smoke plate technology, and the cell size was calculated. The pressure sensors were used to record the arrival time of the detonation wave, and the average propagation velocity of detonation wave was obtained. The results show that the detonation cellular structure closely depends on the thickness and porosity of sponge and wire mesh, and three phases of the propagation can be observed in the tube, including detonation failure, acceleration and re-initiation. In addition, size of the detonation cell is also closely related to the thickness and porosity of sponge and wire mesh. Increasing the thickness of porous materials and decreasing the porosity both can increase the size of the detonation cell. By comparing the effects of sponge and wire mesh on the detonation cellular structure, it can be found that at the same initial condition, the rigid porous material has a stronger inhibition effect on detonation. But the difference will be gradually decreased with the increase of the thickness of the porous materials. Finally, the limit of the detonation propagation is analyzed quantitatively by introducing the dimensionless parameter D_H/λ. For flexible and rigid porous materials, the detonation limit can be nearly quantified as D_H/λ≈3.0 and D_H/λ≈3.1.

To effectively predict slope stability and prevent slope instability occurrence, a hybrid model WOA-RF, combining whale optimization algorithm (WOA) and random forest (RF) was proposed. Based on the collected slope cases, the classification and generalization performance of the model was evaluated according to the classification performance indicators given by the confusion matrix and the area under the receiver operating characteristic curve. Additionally, WOA was used to optimize four widely used machine learning models, and the optimized machine learning models were compared with WOA-RF. The results demonstrate that WOA is effective in optimizing hyperparameters and improving model performance. The optimal WOA-RF model achieves an accuracy of 0.99 on training set and of 0.94 on test set. After optimization, the accuracy, the precision, the recall, and the hamonic mean of the precision and recall are increased by 11.9%, 19.0%, 4.8%, and 11.9%, respectively. Comparative analysis reveals that the WOA-RF model is superior to the others in all indicators. Furthermore, the feature importance ranking was determined. Analysis of the feature importance indicates that unit weight is the most sensitive feature affecting slope stability. The established WOA-RF model is proved effective in predicting slope stability and facilitating the development of appropriate protective measures based on the predicted results.