Since the successful synthesis of bulk sp³ amorphous carbon in 2021, this material has attracted considerable attention owing to its ultrahigh hardness, mechanical isotropy, potential for shaping and machining, and distinctive electronic structure. These features make it a promising candidate for applications in ultra-precision machining and optoelectronic detection. Recent studies have mainly focused on the formation mechanism, thermodynamic stability, structural and property regulation, and synthesis process optimization of sp³ amorphous carbon materials derived from fullerenes under high-pressure and high-temperature conditions. These studies have not only deepened the understanding of the formation mechanism of sp³ amorphous carbon, but also promoted the further development of its functional applications. This review systematically summarizes the relevant research progress and discusses future key directions, including the large-size and high-quality synthesis, precision shaping, and functional application expansion of sp³ amorphous carbon.

Fullerenes, represented by C₆₀ and C₇₀, are typical molecular-crystal carbon allotropes. Under high-temperature and high-pressure (HTHP) conditions, they can undergo a continuous sequence of structural evolution, including orientational ordering, initial intermolecular bonding, low-dimensional polymerization, multidimensional cross-linking, cage collapse, and amorphization. Therefore, fullerenes serve as an important bridge between molecular-crystal carbon and high-density covalent carbon networks. This review focuses on the phase transitions and polymerization behavior of fullerenes under combined pressure-temperature control. The structural features and formation mechanisms of the fcc to sc orientational transition, dimerization, typically through [2+2] cycloaddition, one-dimensional chain polymerization, two-dimensional layered polymerization, including tetragonal and rhombohedral phases, and possible three-dimensional structures are systematically summarized. The effects of different loading paths and kinetic factors on phase boundaries and product ordering are also discussed. In addition, the multi-pathway competition and disordering tendency of C₇₀ driven by molecular anisotropy are comparatively reviewed. The regulatory roles of guest species in metallofullerenes and solvated fullerenes on the polymerization pathways and physical properties of fullerenes under HTHP conditions are further discussed. Finally, based on recent progress in fullerene-derived sp³-rich superhard amorphous carbon and related novel carbon structures, potential research directions for the controllable synthesis of high-pressure carbon materials through precursor engineering and multidimensional regulation strategies are proposed.

Aluminum nitride (AlN) ceramics are important heat-dissipation materials for high-power electronic devices. However, the high sintering temperature required by conventional processing routes limits practical application of AlN ceramics and increases fabrication costs. Therefore, it is necessary to develop preparation method that is capable of achieving densification at relatively low temperature. To address the difficulty of simultaneously obtaining high densification and high thermal conductivity in polycrystalline AlN ceramics under reduced-temperature sintering conditions, this work adopts a stepwise research strategy. First, the densification behavior and thermal conductivity of pure AlN under high-pressure assistance were investigated to identify the optimal sintering conditions. Under additive-free conditions, pure-phase AlN ceramics with clean grain boundaries and high densification were prepared at 5.0 GPa and 1400 ℃, achieving a thermal conductivity of 101.6 W/(m·K). Based on these optimized conditions, the AlN/diamond composite system was further studied, and the effects of diamond volume fraction on the structure and properties of the composites were systematically examined. The results show that the thermal conductivity of the composites first decreases and then increases with increasing diamond volume fraction, reaching 112.4 W/(m·K) at 33.3%. Mechanistic analysis indicates that interfacial thermal resistance dominates at low diamond contents, whereas at high diamond contents the enhancement of heat transport by thermally conductive diamond pathways becomes more significant. By taking full advantage of the processing benefits of high-temperature and high-pressure technology, this work achieves substantial improvement of AlN-based materials at temperatures lower than those required in conventional sintering, thereby providing a new route for the low-temperature fabrication of high-performance thermally conductive ceramics.

Metastable high-entropy alloys can exhibit coupled phase transformation, strain localization and damage evolution under shock loading, and their spall responses are governed by both the loading intensity and the duration of the stress pulse. To clarify the distinct roles of impact velocity and pulse duration in spallation behavior and void evolution, plate-impact experiments were conducted on a Si₄V₅Mn₅Cr₁₀Co₃₀Fe₄₆ metastable high-entropy alloy using a single-stage light-gas gun. The free-surface velocity response, spall parameters, local microstructural evolution and three-dimensional void morphology under different loading conditions were systematically investigated. The results show that, at a fixed specimen thickness, increasing the impact velocity from 282 m/s to 553 m/s markedly raises the peak free-surface response and the peak compressive stress, whereas the spall strength only slightly changes. Meanwhile, internal voids evolve from dispersed nucleation to localized clustering, accompanied by increased fractions of HCP/BCC (hexagonal close-packed/body-centered cubic) phases and a pronounced rise in high-KAM (kernel average misorientation) regions near the voids, suggesting that higher impact velocity promotes local phase transformation, lattice distortion and concentrated damage development. Micro-X-ray computed tomography further reveals that increasing impact velocity drives the voids towards larger volumes, stronger spatial concentration and more complex morphologies. In contrast, under nearly constant impact velocity, as the specimen thickness increases from 1.0 mm to 2.0 mm, the pulse duration is prolonged from 0.075 μs to 0.250 μs, and the spall strength correspondingly increases from 1.40 GPa to 1.83 GPa. The spatial distribution of voids gradually changes from dispersed to centrally concentrated, with an enhanced tendency for interconnection, indicating that longer pulse duration demonstrates greater favorability towards damage accumulation and localized coalescence. By combining free-surface velocity histories, two-dimensional microstructural characterization and three-dimensional void statistics, it is shown that the impact velocity mainly controls the instantaneous driving force for the damage during spallation, whereas the pulse duration primarily governs the time window for the damage accumulation and the extent of localization. Together, these two factors determine the nucleation sites, growth paths and final failure mode of spall damage in this metastable high-entropy alloy.

Obtaining the mechanical response of CuCrZr alloy under coupled electro-magnetic-thermal-mechanical loading is significant for the engineering application of CuCrZr alloy, which is one of the candidate materials for electromagnetic railgun rails. This paper proposes an external-magnetic-field-assisted electromagnetic expanding ring technique, which stably achieves high strain rate loading exceeding 10⁴ s^–1 without the significant increase in the induced current and Joule heating temperature rise in the metal sample ring. Based on this technique, a study on the dynamic tensile properties of CuCrZr alloy under coupled electro-magnetic-thermal-mechanical loading was conducted. The stress-strain curves and fracture strain of CuCrZr alloy under conditions of high current density, high strain rate, high temperature rise rate, and strong magnetic field were obtained. The results provide important references for the application of CuCrZr alloy under multi-physics field coupling conditions.

High-entropy carbides (HECs), which are characterized by pronounced chemical disorder and lattice distortion, exhibit exceptional strength-toughness synergy and are promising candidates for impact protection and high-temperature structural applications. However, their microstructural evolution and stress response under extreme conditions, such as high stress and strain rates, remains poorly understood. In this work, a high-accuracy machine-learning interatomic potential is employed to investigate the representative multi-principal carbide (Zr_0.2Hf_0.2Ti_0.2Nb_0.2Ta_0.2)C (HEC) through large-scale molecular dynamics (MD) simulations. To elucidate how multiple “high-entropy” effects govern atomic-scale plasticity in HECs, large-scale MD simulations are carried out to explore their response under quasi-isentropic compression and ramp-wave loading along three principal crystallographic orientations: [001], $ [01\overline{1}] $, and [111]. The results demonstrate that the high-entropy effects profoundly reshape the initiation of plasticity, the competition among slip systems, and the localized deformation modes in HEC. Local stress fluctuations and lattice distortions enhance transient Bain-type stacking rearrangements within the sublattice and promote the synergistic activation of multiple slip systems. This leads to a transformation of shear band formation from isolated nucleation to a network-like propagation. Complementary first-principles calculations reveal that the carbon vacancy formation energy in high-entropy ceramics is significantly reduced compared to their single-component carbides. This reduction of vacancy formation energy facilitates preferential displacement of carbon atoms and their participation in shear band nucleation during compression. Furthermore, the comparison between different loading paths highlights the complexity of the high-entropy effects’ response. The quasi-isentropic loading path helps to unveil the intrinsic deformation mechanisms governed by the high-entropy effect itself, whereas the stress gradients inherent in ramp-wave loading couple with the high-entropy effect, leading to a premature triggering and intensification of plastic localization.

This work integrates stochastic theory with a phase-field model for spallation in ductile metals. By assigning four distinct random distributions to the initial yield strength to characterize the random distribution of material defects and employing an explicit dynamic solver, the entire process of spall damage—from gradual evolution to instability and coalescence—was successfully simulated. The simulation results were validated through plate impact experiments and triangular wave loading experiments. These validations revealed the relationship between the heterogeneity of material yield strength and both the spall strength and the number/area of damaged zones. The results indicate a negative correlation between the standard deviation of the initial yield strength and the spall strength, which holds for both single and multiple spall scenarios in ductile metals. For single spallation, regardless of the initial distribution of yield strength, the resulting spall strength follows a normal distribution. For multiple spallation, the number of initially nucleated damaged zones increases linearly with the standard deviation, while the size of these zones follows a Weibull distribution. Under the same initial random distribution, the number of damaged zones evolves over time, showing a trend of initial slow growth, subsequent acceleration until saturation, and a final decline after saturation. This trend corresponds to the typical process of damage evolution involving nucleation and coalescence during spallation.

This study systematically investigated the effects of temperature on the spall behavior of Invar36 alloy through plate impact experiments and microstructural characterization techniques. Utilizing a single-stage light gas gun loading platform combined with a high-temperature heating device, the experiments measured free surface velocity profiles and spall strength variations in samples with different segregation orientations within the temperature range of 20 ℃ to 300 ℃. Results demonstrate that the spall strength of Invar36 alloy exhibits a linear decrease with increasing temperature, with elevated temperatures significantly weakening its dynamic tensile resistance. Microstructural damage analysis reveals that at room temperature, voids nucleate and propagate along element segregation bands, while high-temperature damage concentrates at grain boundaries. Elevated temperatures reduce the constraining effect of segregation and facilitate material softening through thermally activated dislocation motion. The research elucidates the central role of temperature in governing spall strength and damage mechanisms, providing a theoretical foundation for failure-resistant design of Invar36 alloys under high-temperature impact conditions.

The space debris problem has become one of the most pressing challenges in the field of space environment protection. Currently, most spacecraft shielding systems adopt Whipple-type structures, in which aluminum alloys are commonly used as bumper materials. In this study, the smoothed particle hydrodynamics (SPH) method implemented in the AUTODYN software was employed to numerically investigate the hypervelocity impact of spherical projectiles on high-entropy alloy (HEA) protective structures. The characteristics of the resulting debris clouds, including fragment number, mass distribution, and momentum, were systematically analyzed under various impact conditions. In addition, the effects of impact velocity and the ratio of bumper thickness to projectile diameter (t/D) on the hypervelocity impact response of HEA shielding structures were examined. The results show that, under identical impact conditions, the debris cloud characteristics generated by HEA protective structures differ significantly from those of aluminum alloy structures, namely: the total number of fragments increases by approximately 51.86%; the number of small-mass fragments increases by about 79.56%, while the number of large-mass fragments decreases; and the maximum debris cloud momentum along the impact direction (z-direction) is less than 75% of that associated with aluminum alloy structures across multiple projectile diameters. Parametric analyses indicate that the expansion of the debris cloud is primarily governed by impact velocity, with higher velocities leading to faster expansion, while the influence of the t/D is relatively minor. In contrast, the mass and kinetic energy of hazardous fragments (large-mass/high-energy fragments) are mainly affected by t/D, with higher values resulting in greater impact severity. These findings provide theoretical support and reference for the application of high-entropy alloys in next-generation spacecraft shielding structures.

Micro-jetting and micro-spallation at metal interfaces under intense shock loading play pivotal roles in applications such as inertial confinement fusion (ICF). These phenomena exhibit inherent complexity due to their multi-scale dynamics, strong nonlinearity, and coupled multi-field interactions. Under extreme irradiation conditions, the formation of high-pressure nanoscale helium bubbles significantly alters interface failure mechanisms. Using molecular dynamics methods, we investigate micro-jet growth and damage evolution in helium-containing copper subjected to double supported shock loadings. Helium bubbles demonstrate lower critical activation stress thresholds for expansion compared to void nucleation, with these thresholds being dependent on bubble distribution and number density. Under low-pressure primary shocks, helium-containing metals produce more pronounced micro-jets than pure metals. During secondary shocks, helium bubbles promote jet fragmentation, resulting in higher maximum velocities at micro-jet tips while maintaining comparable velocity distributions in micro-jet bodies. Secondary shocks show negligible effects on bulk helium bubbles that were previously compressed by initial shocks and partially rebounded due to rarefaction waves without complete recovery. Near-surface ruptured bubble walls may reattach to bubble bases after secondary shocks, temporarily re-trapping helium atoms that are subsequently released during unloading-induced re-expansion and rupture. The collapse mechanism of helium bubbles under secondary shock is closely related to the helium bubbles size and the strength of secondary shock. This study establishes fundamental physical understanding and provides a theoretical foundation for future cross-scale investigations of coupled micro-jetting and micro-spallation evolution in irradiated helium-containing metals.