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.

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.

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.

In this work, we have performed extensive swarm-intelligence structures searching simulations on the RbBSi compounds within the pressure range from 0 to 100 GPa. We have proposed three different phases of RbBSi, of which the stability, the electronic structure and the potential superconductivity were calculated by first-principles calculations. All predicted phases are thermodynamically and dynamically stable within the studied pressure range. The bands of the three phases crossing the Fermi level indicate the structures are all metallic. In addition, P4/nmm-RbBSi is a superconductor with T_c of 14.4 K at ambient pressure. This work extends the understanding and potential application of alkali metal boron-silicide compounds in the field of superconductor.

The curved steel-concrete-steel composite structure is a sandwiched structural member, consisting of two curved steel plates and concrete core. Headed studs are used to connect the steel plates and concrete to achieve the composite effect. This type of structure is promising for improving earthquake resistance and anti-blast performance, and has been applied in super high-rise structures, offshore platforms, and nuclear power facilities. This paper conducts experimental and numerical analysis to investigate the damage mode and mechanism of the curved steel-concrete-steel composite slab. Additionally, a parametrically analysis is conducted to explore the impact of blast distance, steel plate thickness, arch heights, and stud spacing on its anti-blast performance. The results indicate that the curved steel-concrete-steel composite structure performs well globally and retains their structural load-bearing capacity without failure after subjecting to blast loading. Increasing the blast distance and steel plate thickness can effectively reduce the concrete damage and the span deflection of the composite slab. Reducing arch heights causes a switch in concrete damage from compression damage to tensile damage, which is more severe and results in larger span deflection of the slab. Although reducing stud spacing increases the concrete plastic damage, it reduces the span deflection of the composite slab. The research results can contribute to the design and applications of curved steel-concrete-steel composite structures.

Since the discovery of 4.2 K superconductivity in mercury, the search for room-temperature superconductivity has been a hot topic in the field of condensed matter physics. In recent years, scientists have discovered a series of high-temperature superconductivity, represented by covalent H₃S (superconducting transition temperature T_c=203 K) and ionic LaH₁₀ (T_c=250 K) and CaH₆ (T_c=215 K) under high pressures. These works have successively broken superconducting temperature records, opening a new era in search for room-temperature superconductivity in hydrogen-rich compounds. This paper focuses on the progress of theoretical prediction, experimental synthesis, and characterization in binary and ternary hydrogen-rich superconductors with high critical temperature under high pressure. Furthermore, it addresses the challenges and potential avenues in the quest for room-temperature superconductors in hydrogen-rich compounds.

In order to investigate the propagation characteristics and thermal shock dynamics of multiple explosive sources gas explosion in complex roadways, numerical simulations were conducted using the Fluent software under three types of dual explosive sources arrangements in the H-type tunnel, including the same side, opposite positions, and diagonal positions. It was found that, after the two explosive sources in the tunnel were ignited simultaneously, its prodromic shock wave propagated along the unburned area of the tunnel. When the two shock waves encountered, the pressure superimposed while the impulse canceled out, and the propagation of flame was blocked by the pressure superposition area, resulting in a slowdown or reversal of the speed. Compared to the single source explosion, the dual explosive sources led to a higher pressure in specific areas such as contact lane, center of bifurcation, and sidewalls. Extreme pressure zones occur at the closed end of the roadway under same-side and diagonal arrangement conditions and at the center of the bifurcation under the opposite arrangement condition.

Zr-based amorphous fragment is an emerging active and efficient destructive element, which will undergo a deflagration reaction and fragmentation when its impact velocity reaches its threshold. The deflagration reaction and fragmentation could greatly increase its behind-armor destructive capability. In order to study the penetration damage mechanism and behind-armor destructive capability of Zr-based amorphous fragments on carbon fiber reinforced composites, a ballistic gun was used to load the spherical fragments to impact 8 and 6 mm thick carbon fiber composite targets at velocities ranging from 496.4 m/s to 1085.8 m/s and 571.4 m/s to 1103.9 m/s, respectively. Then a 2 mm thick LY12 aluminum target plate was arranged behind the target to measure the damage capability under different working conditions. The test results showed that the mainly failure mode of strike face was a coupling failure mode of compression failure and shear failure, and the main failure mode of its back face was a coupling failure mode of tensile failure and the de-sticky splitting of the layer. With the increase of the impact velocity, the proportion of the compression and shear coupling damage of the carbon fiber composite target plate was gradually increased, and the phenomenon of tensile breakage and delamination was gradually decreased. The ballistic ultimate velocities of the fragment for 8 and 6 mm thick carbon fiber composite target were 351.9 and 264.6 m/s, respectively. Behind-armor damage area of the fragment impacted on the 8 mm thick carbon fiber composite target was larger than that of the 6 mm thick carbon fiber target under the same impact velocity. The difference of behind-armor damage area impacted on 8 and 6 mm thick carbon fiber composite targets decreased with the increase of the impact velocity. The behind-armor damage ability of the fragment impacting on the carbon fiber composite target increased with the increase of the impact velocity.

In order to study the effect of charge size on the cook-off characteristics of pressed charges, the calculation model of cook-off process was established for HMX-based pressed charges. The cook-off bombs with different charge sizes were simulated by Fluent software, the effect of charge size on the ignition position, response temperature and response time of pressed charges at different heating rates was calculated. It was found that, at the same heating rate, the response temperature of the charge center is the highest when the length-diameter ratio of HMX-based pressed explosive is 1.0, and the ignition temperature of the charge center decreases with the increase of the length-diameter ratio when the length-diameter ratio is greater than 1.0. When the length-diameter ratio increases to a certain extent, the response temperature of the charge center tends to be a constant. The ignition position of the charge is determined by both the heating rate and the size of the charge, and the ratio of heat transfer between the end face and the periphery face of the charge is inversely proportional to the square of the length-diameter ratio. When the heating rate is slow or the length-diameter ratio is small, the ignition position of the charge is located at the charge center; when the heating rate is fast and the length-diameter ratio is large, the ignition position of the charge is gradually away from the charge center.