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Super-gravity field was reported to strongly intensify the buoyancy-driven flow of liquid during solidification, affecting the solute convection and morphology of eutectic structure in binary alloys. In ternary eutectic alloys, certain two-phase regions with a coarse structure can usually be detected concurrently along with three-phase eutectics, leading to the formation of heterogeneous structure with limited ductility. Currently, Al–Ce–Ni ternary eutectic alloy was chosen as a modal system, which was reported for the first time to be solidified under super-gravity field with high volume fraction of three-phase eutectics. Meanwhile, the formation of ultrafine-fibrous interconnected Al11Ce3–Al3Ni eutectic clusters with more “chains” and higher spatial connectivity was detected mainly due to the relatively higher nucleation rate. The high volume fraction and refinement of interconnected Al11Ce3–Al3Ni eutectic clusters with excellent thermal stability could contribute to enhancement of ductility and tensile strength at elevated-temperature. Interestingly, the strength retention at 300 °C and 400 °C were able to reach up to ∼68.1 % and ∼33.2 %, respectively.

Areal density gradient flyers (ADGFs) have important applications in quasi-isentropic compression and high strain rate loading. The wave impedance gradient distribution of the reported ADGFs is single, and the effects of different wave impedance gradient distributions and spikes number density on the loading results are unknown. In this study, the resin-based ADGFs with different spike areal density distribution and spikes number density were designed and prepared using projection micro stereolithography technology (PμSL). The printing accuracy of ADGFs was evaluated using three-dimensional optical profiler, optical microscope, Scanning Electron Microscopy (SEM) and ultra depth of field microscope. The loading process of the ADGF on the target was studied by experiment and simulation. The simulation result was consistent with the experimental result. Augmenting the wave impedance distribution index (P) of spikes and spikes number density increases the loading strain rate. Due to the high printing accuracy of PμSL, the fine ADGF structures with large spikes number density can be prepared, thereby promoting the formation of quasi-isentropic compression plane waves. This work realizes the regulation of loading strain rate under shockless quasi-isentropic compression, which is significant for understanding the mechanical response of materials under high strain rate loads.

Abstract Background The selenomethionine cycle (SeMTC) is a crucial pathway for the metabolism of selenium. The basic bioinformatics and functions of four enzymes involved in the cycle including S-adenosyl-methionine synthase (MAT), SAM-dependent methyltransferase (MTase), S-adenosyl-homocysteine hydrolase (SAHH) and methionine synthase (MTR), have been extensively reported in many eukaryotes. The identification and functional analyses of SeMTC genes/proteins in Cardamine hupingshanensis and their response to selenium stress have not yet been reported. Results In this study, 45 genes involved in SeMTC were identified in the C. hupingshanensis genome. Phylogenetic analysis showed that seven genes from ChMAT were clustered into four branches, twenty-seven genes from ChCOMT were clustered into two branches, four genes from ChSAHH were clustered into two branches, and seven genes from ChMTR were clustered into three branches. These genes were resided on 16 chromosomes. Gene structure and homologous protein modeling analysis illustrated that proteins in the same family are relatively conserved and have similar functions. Molecular docking showed that the affinity of SeMTC enzymes for selenium metabolites was higher than that for sulfur metabolites. The key active site residues identified for ChMAT were Ala269 and Lys273, while Leu221/231 and Gly207/249 were determined as the crucial residues for ChCOMT. For ChSAHH, the essential active site residues were found to be Asn87, Asp139 and Thr206/207/208/325. Ile204, Ser111/329/377, Asp70/206/254, and His329/332/380 were identified as the critical active site residues for ChMTR. In addition, the results of the expression levels of four enzymes under selenium stress revealed that ChMAT3-1 genes were upregulated approximately 18-fold, ChCOMT9-1 was upregulated approximately 38.7-fold, ChSAHH1-2 was upregulated approximately 11.6-fold, and ChMTR3-2 genes were upregulated approximately 28-fold. These verified that SeMTC enzymes were involved in response to selenium stress to varying degrees. Conclusions The results of this research are instrumental for further functional investigation of SeMTC in C. hupingshanensis. This also lays a solid foundation for deeper investigations into the physiological and biochemical mechanisms underlying selenium metabolism in plants.

Abstract Despite numerous reports indicating the significant impact of RNA modification on malignant glioblastoma (GBM) cell behaviors such as proliferation, invasion and therapy efficacy, its specific involvement in glioblastoma (GBM) angiogenesis is remains unclear and is currently under investigation. In this study, we aimed to investigate the relevance between RNA modification regulators and GBM angiogenesis. Our study employed bioinformatic analyses, including Gene Set Enrichment Analysis (GSEA), differential expression analysis, and Kaplan–Meier survival analysis, to identify regulators of angiogenesis-associated RNA modification (RM). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were applied to identify the enrichment of angiogenesis associated signatures in ALKBH5-high expression GBMs. We also utilized Western blot to verify the upregulation of ALKBH5 in clinical GBM samples. By a series of in vitro and in vivo assays, including plasmid transfection, wound healing, transwell invasion test, tube formation, RT-qPCR, ELISA assays and xenograft mice model, we validated the angiogenesis regulation ability of ALKBH5 in GBM. The N6-methyladenosine (m6A) modification “erase” ALKBH5 emerged as a candidate regulator associated with angiogenesis, demonstrating elevated expression and robust prognostic predictive ability in GBM patients. We also revealed enrichment of vasculature development biological process in GBMs with high ALKBH5 expression. Subsequently, we validated the elevated the expression of ALKBH5 in clinical GBM and paired adjacent tissues through western blot. Additionally, we knocked down the expression of ALKBH5 using sh-RNAs in U87 GBM cells to access the angiogenesis induction ability in U87 cells. In vitro experiments, Human Umbilical Vein Endothelial Cells (HUVECs) were used to perform wound healing, transwell migration and tube formation analysis, results indicated that ALKBH5 knock-down of U87 cells could decrease the pro-angiogenesis ability of U87 GBM cells. Further validation of our bioinformatic findings confirmed that ALKBH5 knockdown impaired VEGFA secretion in both in vitro and in vivo settings in U87 cells. These results comprehensively affirm the crucial role of ALKBH5 in regulating GBM-induced angiogenesis, both in vitro and in vivo. ALKBH5 not only emerges as a promising prognostic factor for GBM patients, but also plays a pivotal role in sustaining GBM progression by promoting angiogenesis.

TaC enhancement particles and Re alloy were used to improve the strength and ductility of the tungsten alloy. The synergetic effect of TaC addition and Re alloying on relative density, microstructure, and mechanical properties of tungsten alloy were investigated. The results indicated that a W-based composite with 2.5 wt% TaC addition and 25 wt% Re alloying exhibited yield stress of 1.23 GPa, the ultimate compressive stress of 2.86 GPa, bending strength of 1.30 GPa and strain capacity of 42 %, which was increased by 114 %, 140 %, 226 %, and 133 % than those of pure W. Further analysis revealed that the grain boundary purification, grain refinement, and kinematic strain gradient contribution because of the addition of TaC, lattice distortion, and the generation of dislocations because of the addition of Re alloying are the main strengthening mechanisms in W–TaC-Re composite.

In this paper, finite element models of ultrasonic wave propagation in Cu–PMMA composites are established. The effects of second-phase particles, ultrasonic properties, and graded interfaces on the ultrasonic propagation behavior are investigated, and the contributions of particle-independent scattering, particle interactions, and matrix viscoelasticity to the ultrasonic attenuation are quantitatively evaluated. The results show that there is no obvious coupling between particle scattering and matrix viscoelasticity in Cu–PMMA composites, and the longitudinal wave speed has little effect with the variation of particle size, ultrasonic frequency, and graded interface, while the variation of the acoustic attenuation coefficient is related to the disorder of ultrasonic energy propagation direction. In the intra-layer uniform model, with the increase in Cu particle size and ultrasonic frequency, the scattering effect of Cu particles on the ultrasonic waves is enhanced, resulting in a significant increase in the acoustic attenuation coefficient. In the inter-layer graded multilayer model, there is a strong reverse energy propagation between the layers, causing the acoustic attenuation coefficient to increase significantly.

We reported a novel method to prepare Al–Si/SiC composites infiltrated under super-gravity field without Mg addition. Noted that centrifugal force acted as the main driving force to overcome the penetration resistance, making it feasible to obtain the Al–Si/SiC composite with high relative density (≥99.3 %). The interfacial reaction between Al and SiC was retarded by Si addition under super-gravity field. Interestingly, the rod-like eutectic Si was detected at Al–SiC interface with semi-continuous distribution, leading to the excellent bending strength (342.6 ± 1.0 MPa), enhanced thermal conductivity (173 W/m K at 373 K), and relatively low coefficient of thermal expansion (8.90 × 10−6 K−1 ranged from 323 to 373 K). The interfacial regulation and fracture mechanism were discussed in details.

Sandwich structure has been designed to reduce the impact damage of the stress waves. However, the existing work focuses on the optimization of sandwich cores while the face-sheet structure is seldom improved. Here, we used the impedance matching theory to design a negative gradient face-sheet sandwich structure with excellent stress wave attenuation performance. Owing to stress wave attenuation form a high impedance to a low one, the negative gradient face-sheet sandwich structure shows a low peak stress of 5.51 MPa, and the average transmission peak stress is 2.69 MPa. The gradient face-sheet structure changes the compressive deformation behavior; thus, the energy absorption performance of the negative gradient face-sheet sandwich structure increases to be 1311.8 kJ/m3 and the specific energy absorption reaches 1072 J/kg. Finite-element methods further demonstrate the overall sandwich structures can be enhanced through alleviating the failure of sandwich core by a gradient face-sheet structure. This work provides a paradigm for the design of sandwich structures with high energy absorption performance.

Metal/polymer bi-layered composites have been widely applied in vehicles and digital products. However, the metal/polymer joints usually suffer from fracture failure during dynamic load. This work optimizes the surface porosity to obtain good dynamic shear bonding performances of the 5052 aluminum alloy (Al5052)/polymethyl methacrylate (PMMA) interface during the dynamic test. The nominal bonding performance reaches maximum with the Al5052 surface porosity of about 30%/dm2. Simulation with an equivalent macro complementary interfacial model is applied to verify qualitative bonding performance tendencies in the experiment. The experimental data plots are fitted by a piecewise function which includes a power function to represent the fundamental factor and an exponential function to represent the attenuation factor to help propose a method to estimate the porosity range which would achieve better bonding, and to compared with the ideal fitted simulation curves to evaluate the extent of other factors which decrease the dynamic bonding performance. The optimization of the nominal bonding performances obtained by the experiment-led and simulation-supported investigation has given prominence to the significance of the porosity control.

The distribution of second phase particles in the microstructure of composite ceramics affects the mechanical properties, and the intragranular structures often result in better properties compared to the intergranular structures. However, it is difficult to obtain composite ceramics with intragranular structure by conventional route. To produce composite ceramics with an intragranular structure in a simpler route. In this work, starting powders with different phase compositions were obtained by the co-precipitation method, and zirconia toughened alumina (ZTA) composite ceramics were prepared with these starting powders by spark plasma sintering (SPS). The results show that it is easier to fabricate ZTA composite ceramics with an intragranular structure by using composite powders containing amorphous or transition phase Al2O3 as starting materials. The phase composition of the powder prepared by the co-precipitation method after calcination at 1100 °C is θ-Al2O3 and t-ZrO2, and the average grain size after sintering at 1500 °C is 1.04 ± 0.28 µm, and the maximum Vickers hardness and fracture toughness of the specimens reach 19.37 ± 0.43 GPa and 6.18 ± 0.06 MPa·m1/2, respectively. The ZrO2 particles were the core of crystallization and grow together with the Al2O3 matrix, forming the intragranular structure of ZTA ceramics. This work may provide a new idea for preparing composite ceramics with intragranular structure.

Owing to the challenge of capturing the dynamic behaviour of metal experimentally, high-precision numerical simulations have become essential for analysing dynamic characteristics. In this study, calculation accuracy was improved by analysing the impact of constitutive models using the finite element (FE) model, and the deep learning (DL) model was employed for result analysis. The results showed that FE simulations with these models effectively capture the elastic-plastic response, and the ZA model exhibits the highest accuracy, with a 26.0% accuracy improvement compared with other models at 502 m/s for Hugoniot elastic limit (HEL) stress. The different constitutive models offer diverse descriptions of stress during the elastic-plastic response because of temperature effects. Concurrently, the parameters related to the yield strength at quasi-static influence the propagation speed of elastic waves. Calculation show that the yield strength at quasi-static of 6061 Al adheres to y = ax + b for HEL stress. The R-squared (R2) and mean absolute error (MAE) values of the DL model for HEL stress predictions are 0.998 and 0.0062, respectively. This research provides a reference for selecting constitutive models for simulation under the same conditions.

Good impedance matching and attenuation ability of electromagnetic wave absorbing (EMA) materials are required to broaden the effective absorbing bandwidth (EAB) and reduce minimum reflection loss (RLmin), achieving high EMA performance. Here we report a polymethylmethacrylate (PMMA)-based composites foam with alternating and directional (AD) microporous structure that possessing broadened EAB value of 3.53 GHz (8.49–12.02 GHz) and lowered RLmin value of −19.35 dB, was manufactured via the one-step physical constraint foaming technology. Structural studies reveal that the AD microporous structure can induce the carbon nanotubes (CNTs) oriented distribution to improve effective concentration of CNTs, achieving excellent impedance matching. Meanwhile, a large number of parallel-plate capacitors at the multilayer layer interfaces were generated to promote interfacial polarization, including enhancement of multiple reflection and scattering of electromagnetic wave at the layer interfaces. Thereby, the composites foams exhibited high attenuation ability. This study lays the foundation for rational design and synthesis of EMA materials for wideband EMA performance.

In this work, the Hugoniot equation of state for aluminum and copper under low-impact loading was measured by using the plane impact technique and laser Doppler velocimetry. The linear relationship between shock wave velocity and particle velocity was fitted by a least squares method, with D=5.28114+1.306(17)us for an Al pressure range from 2.5 to 13.9 GPa and D=3.9386+1.484(14)us for Cu at 5.7–47.5 GPa. The linear fitting correlation coefficient was greater than 0.99, which was better than the previous experimental data. The results demonstrate that the Doppler pin system has great advantages for measuring the Hugoniot EoS at low shock pressure compared with the electric pin technique The experimental data obtained in this work extend to a lower pressure range. This can provide more accurate Mie–Grüneisen EoS of Al and Cu under low shock pressure.

Hypervelocity impact in the universe can be generated by a three-stage gas gun. Achieving the desirable planarity of the flyer enlarges the experimentally effective area of the flyer under the hypervelocity condition. The multidimensional graded density impactor (MDGDI) enhances the planarity of the flyer. In this investigation, a one-dimensional Lagrange elastoplastic hydrodynamic method and a Euler grid finite difference method were used to examine the relationship between the structure of graded density impactors (GDIs) and the planarity of flyers. MDGDIs lead to a deviation of the stress wave produced by the one-dimensional graded density impactor (1DGDI), which offsets the stress disturbance effect, changes the velocity at each particle, and enhances the planarity of flyers. The proportion of flat areas of the flyer increases from 52.70% to 95.71% by adopting MDGDIs. The proportion of flat areas is linear with the wave impedance of the high-impedance layer for 1DGDIs and the wave impedance near the barrel of the high-impedance layer for MDGDIs. This investigation guides the design of GDIs and expands the application of gas gun technology in the field of hypervelocity impact.

Energetic metastable intermixed composites (MICs) consisting of polyvinylidene fluoride (PVDF) and fuels aluminum (Al) have the potential to be used as propellants and explosives. Our study introduced SPEEK-modified graphene (SPG) prepared by non-covalent modification of sulfonated poly(ether-ether-ketone) (SPEEK) into PVDF/Al to improve its energy release. The optimized interface generated by the interaction between SO3H groups of SPG layer and CF2 dipoles of PVDF layer integrates graphene onto the surface of PVDF/Al particles. Due to the effect of graphene on the interfacial thermal resistance, the enthalpy of SPG coated PVDF/Al particles is about 1.5 times higher than that of uncoated particles. The existence of SPG improves the heat transfer efficiency of MICs. For comparison, reduced graphene oxide (RGO) has also been introduced as an additive. Graphene is introduced to linearly affect(R2 = 0.9865) the main oxidation enthalpy by lifting the surface oxidation heat release of the Al core. Therefore, graphene is a new strategy for increasing the energy release rate while improving the energy output.

In this study, W-Ag matrix composites were fabricated by a relatively low temperature (750 °C) via designing dual-metal-layer (Cu and Ag) coated W powders. The effects of Cu and Ag coated W powders on the densification, microstructure and properties of the composites were investigated. The results indicated that the Cu-Ag coating promotes the sintering process and favors the low-temperature densification of W-Ag matrix composites. Moreover, the Cu-Ag coating benefited the formation of Cu-Ag solution and improved the interfacial bonding. The hardness of W-Ag matrix composites was increased to 260.0 HV by adjusting the composition of the material, and compressive strength can reach 799 MPa. The electrical conductivity can reach 45.0% IACS.

W-Si-C composites with high relative densities and good mechanical and wear properties were successfully prepared by spark plasma sintering. The influence of SiC content on the relative density, microstructure, mechanical properties and wear characteristics was investigated. The results indicated that the reaction between SiC and W at their interface produced W2C and W5Si3. SiC also reacted with oxygen impurities at the W grain boundary to form SiO2. The purification of the grain boundaries of W was carried out by SiO2 synthesis. Reactive sintering reduces the free energy of the system and facilitates the densification process of W-Si-C composites. This results in a significant increase in the relative density of W-Si-C composites, which reaches a maximum of 98.12%, higher than the 94.32% of pure tungsten. The hardness significantly increases from 4.33 GPa to 8.40 GPa when the SiC content is 2 wt% compared to pure tungsten due to the generation of the hard ceramic phase and the increase in relative density. The wear resistance of the W-Si-C composites was significantly improved with little SiC addition. The wear rate significantly decreased from 313.27 × 10−3 mm3/N·m of pure tungsten to 5.71 × 10−3 mm3/N·m of W-0.5 wt% SiC. SEM analyses revealed that the dominant wear mechanism of pure tungsten was attributed to fatigue wear, while that of W-Si-C composites was due to abrasive wear.

Spallation is a typical dynamic fracture mode under shock loading and has attracted the attention of most researchers. However, due to the difficulty in measuring temperature in dynamic experiments, the effect of initial temperature on spalling response has been rarely investigated. Molecular dynamics simulation perfectly corresponds to the short duration and high strain rate of the spalling process. Therefore, in this work, molecular dynamics simulations are used to study the spalling reaction of single-crystal aluminum at different initial temperatures. The research has shown that the evolution of spallation is related to dislocation and hole nucleation. First, the spall strength of the material decreases as initial temperature increases, while the dislocation density gradually increases. However, when the initial temperature increases to 750 K, the dislocation density decreases. Then, the number of holes and the degree of damage change as initial temperature increases. However, at the low impact strength (v < 2.0 km/s), the changes in the number of holes and the degree of damage are highly dependent on the initial temperature. In the case of high impact strength, the opposite is true. Finally, the thermodynamic path of the material during impact compression is studied. It is found that melting may occur during compression, release or tension, and damage stages, depending on the initial temperature and impact strength. The discovery and research of these systems have laid a solid foundation for subsequent studies.

Dense and homogeneous W–Cu composites with high strength were successfully prepared from Cu-coated W powders by hot pressure sintering (800 °C) with Sn as activated additives. The relative density, microstructure and properties of W–Cu composites with Sn additives were studied. The results have indicated that the addition of Sn additives could significantly promote the densification of W–Cu composites. When Sn was added as additives, the sintering process is mainly the sintering between Cu–Cu and Cu–Sn, and the better mobility of Cu–Sn solid solution is help to eliminate pores and promote low-temperature densification. The relative density of sintered composites has reached 99.2% with 2 wt.% Sn additives. Stacking faults and Twin structure can be distinctly observed in the Cu matrix when 2 wt.% Sn was added as additives. With adding of Sn additives，the Vickers hardness has increased to 263.5 HV. The addition of Sn can lead to the strengthening of interface bonding of sintered composites, and the fracture microstructure with the ductile fracture of Cu matrix and the trans-granular fracture of W phase has been observed in the sintered composites with Sn additives. The bending strength of sintered composites has increased to 993.1 MPa due to the transform of fracture mechanism of sintered composites. The coefficient of thermal expansion of sintered composites has reduced to the minimum value of 7.56 × 10−6/K with the 1.5 wt.% Sn additives.

To develop materials with a promising utilization future in the extreme environments of aerospace, the MoNbTa(WC)x composites were prepared by vacuum arc melting, of which the crystal structure, microstructure, and compression properties at elevated temperature were investigated. The MoNbTa(WC)x composites had eutectic structures that consisted of body-centered cubic (BCC) phase and eutectoid structures. The lamellar fine eutectoid structures were composed of BCC-structured high entropy alloy (HEA) Mo-Nb-Ta-W and FCC-structured carbide Mo-Nb-Ta-W-C. It was demonstrated that the ductility and elevated temperature strength was enhanced simultaneously combined with the effect of eutectic structures and WC addition. The optimal true yield strength and true fracture strain reached 1205 MPa and 29.2% in MoNbTa(WC)0.9 at 1200 °C, meanwhile, the fracture strain at ambient temperature was 13.96%. Distinct strain hardening was observed at the initial deformation stage of MoNbTa(WC)0.9 at 1200 °C. The compression performances of MoNbTa(WC)x were superior in comparison with most refractory high entropy alloys.

Particulate polymer composites (PPCs) are widely applied under different elastic wave loading conditions in the automobile, aviation, and armor protection industries. This study investigates the elastic wave propagation behavior of a typical PPC, specifically a Cu/poly (methyl methacrylate) (PMMA) composite, with a wide range of particle contents (30–65 vol. %) and particle sizes (1–100 μm). The results demonstrate an inflection phenomenon in both the elastic wave velocity and attenuation coefficient with increasing volume content. In addition, the inflection point moves to the direction of low content with the increase in particle size. Notably, the elastic wave velocity, attenuation, and wavefront width significantly increased with the particle size. The inflection phenomenon of elastic wave propagation behavior in PPCs is demonstrated to have resulted from particle interaction using the classical scattering theory and finite element analysis. The particle interaction initially intensified and then reduced with increasing particle content. This study elucidates the underlying mechanism governing the elastic wave propagation behavior of high particle content PPCs and provides guidelines for the design and application of wave-absorbing composites.

Thin multi-layered materials are widely used in key structures of many high technology industries. To ensure the quality and safety of structures, layer thickness measurement by non-destructive testing (NDT) techniques is essential. In this paper, a novel approach for the measurement of each layer’s thickness in thin multi-layered material is proposed by using ring-shaped laser generated focused ultrasonic bulk waves. The proposed method uses a ring-shaped laser with a variable radius to generate shear waves with variable focus inside the structure. By analyzing the signal characteristics at the ring center when the laser radius varies from zero to maximum, the direct measurement of layer thickness can be realized, considering that only when the focal depth and the layer thickness satisfy the specific relationship, the reflected shear waves converge and form a peak at the ring center. This straightforward approach can increase the pulse-echo SNR and prevent the processing of aliasing signals, and therefore provides higher efficiency and accuracy for the layer thickness measurement. In order to investigate the feasibility of this method, finite element simulations were conducted to simulate the ring-shaped laser generated ultrasonic waves in multi-layered structure in detail. Following the principle of the proposed method, the layer thickness of a bi-layer and 3-layer structure were respectively measured using simulation data. The results confirm that the proposed method can accurately and efficiently measure the layer thickness of thin multi-layered material.

There is a growing trend towards securitization of the maritime commons, which seriously impacts sustainable fisheries governance cooperation. This impact is mainly reflected in the fact that it undermines the effectiveness of the international legal framework for sustainable fisheries governance, which is fragmented and runs based on countries’ willingness. It makes the international legal basis for sustainable fisheries governance cooperation more fragile. As a result, countries are more inclined to take the issues of sustainable fisheries governance and its sub-issues as security-related issues or tools for achieving maritime security strategies. Ultimately, it will lead to confrontation rather than cooperation in sustainable fisheries governance. Evidence that can support this theory is from combating IUU fishing, a sub-issue of sustainable fisheries governance, in the Northeast Asia Pacific and the South China Sea. From securitization theory and international law theory perspectives, desecuritization is the core of the solutions, including the desecuritization of the maritime commons and the desecuritization of its sub-issues. In practice, desecuritization includes improving the effectiveness of the international legal framework for sustainable fisheries governance and establishing regional cooperative governance mechanisms. The result will certainly help to promote sustainable fisheries governance cooperation on a regional and global scale.

With the need of developing new materials, exploring new phenomenon, and discovering new mechanisms under extreme conditions, the response of materials to high-pressure compression attract more attention. However, the high-pressure state deviating from the Hugoniot line is difficult to realize by conventional experiments. Gas gun launching graded materials could reach the state. In our work, the corresponding Al-Cu composites and graded materials are prepared by tape casting and hot-pressing sintering. The microstructure and the acoustic impedance of the corresponding Al-Cu composites are analyzed to explain the impact behavior of Al-Cu graded materials. Computed tomographic testing and three-dimension surface profilometry machine results demonstrated well-graded structure and parallelism of the graded material. Al-Cu GMs with good parallelism are used to impact the Al-LiF target at 2.3 km/s using a two-stage light-gas gun, with an initial shock impact of 20.6 GPa and ramping until 27.2 GPa, deviating from the Hugoniot line.

An easy direct bonding method to join polymers and metals without using complex equipment was developed in this paper. The results showed that microcraters and nanopores were obtained after chemical treatment, the interface in cross-section fit well and formed interlocks at the microscale, and the polymer resin had friction interaction at the nanoscale with the metal during de-bonding. The bonding strength and failure work values reached 6.45 MPa and 316 mJ/cm2, respectively. The images of the de-bonded polymer surfaces indicated that the interlocks were established by the polymer which diffused into the pores after the vaporing of the bonding solvent and underwent different degrees of deformation when the metal surface was filled with different scales of complex nanopores network structure, which is a determinant of obtaining bonding strength, while on the other hand, negative factors to the bonding performance were also discussed. The processing procedures were investigated to obtain the effective parameters which could process the Al5052 surface full of nanopores network.

Micron-sized aluminum (Al) powders are extensively added to energy-containing materials to enhance the overall reactivity of the materials. However, low oxidation efficiency and energy release limit the practical application of Al powders. Polyvinylidene fluoride (PVDF), the most common fluoropolymer, can easily react with Al to form aluminum fluoride (AlF3), thus promoting the oxidation of Al powders. In this paper, core-shell structured Al@PVDF powders were synthesized by solvent/non-solvent method. Thermal analysis results show that the weight and exothermic enthalpy of Al@PVDF powders are 166.10% and 11,976 J/g, which are superior to pure Al powders (140.06%, 6560 J/g). A detailed description of the oxidation mechanisms involved is provided. Furthermore, constant volume pressure results indicate that Al@PVDF powders have outstanding pressure output ability in the environment of 3 MPa oxygen. The study provides a valuable reference for the application of Al powders in energetic materials.

With their excellent mechanical properties, Cu/Ta metallic nanolayered composites (MNCs) are extensively applied in aerospace and nuclear industry facilities. However, shear localization severely disrupts the ability of these materials to deform uniformly, attracting many researchers. The necessary time and length conditions of experiments limit the investigation of shear localization; thus, relevant studies are insufficient. The molecular dynamics simulation perfectly corresponds to the short duration and high strain rate of the deformation process. Therefore, in this study, we used molecular dynamics simulations to explore the effect of layer thickness on the shear localization of Cu/Ta MNCs with Kurdjumov–Sachs (KS) orientation–related interfaces. Our research demonstrates that shear localization occurs in samples with layer thicknesses below 2.5 nm, resulting in an inverse size effect on the flow strength. The quantitative analysis indicates that the asymmetry of dislocations in the slip transmission across the interface causes interface rotation. This activates dislocations parallel to the interface to glide beyond the distance of individual layer thicknesses, eventually forming shear bands. Both interface rotation and sliding dominate the plastic deformation in the shear band region. In addition, the dislocation density and amorphous phase increase with decreasing layer thickness.

As a representative type of superalloy, Inconel 718 is widely employed in aerospace, marine and nuclear industries. The significant work hardening behavior of Inconel 718 can improve the service performance of components; nevertheless, it cause extreme difficulty in machining. This paper aims to investigate the influence of chamfered edge parameters on work hardening in orthogonal cutting of Inconel 718 based on a novel hybrid method, which integrates Coupled Eulerian-Lagrangian (CEL) method and grain-size-based functions considering the influence of grain size on microhardness. Orthogonal cutting experiments and nanoindentation tests are conducted to validate the effectiveness of the proposed method. The predicted results are highly consistent with the experimental results. The depth of work hardening layer increases with increasing chamfer angle and chamfer width, also with increasing feed rate (the uncut chip thickness). However, the maximum microhardness on the machined surface does not exhibit a significant difference. The proposed method can provide theoretical guidance for the optimization of cutting parameters and improvement of the work hardening.

Cellular media materials are used for automobiles, aircrafts, energy-efficient buildings, transportation, and other fields due to their light weight, designability, and good impact resistance. To devise a buffer structure reasonably and avoid resource and economic loss, it is necessary to completely comprehend the constitutive relationship of the buffer structure. This paper introduces the progress on research of the mechanical properties characterization, constitutive equations, and numerical simulation of porous structures. Currently, various methods can be used to construct cellular media mechanical models including simplified phenomenological constitutive models, homogenization algorithm models, single cell models, and multi-cell models. This paper reviews current key mechanical models for cellular media, attempting to track their evolution from their inception to their latest development. These models are categorized in terms of their mechanical modeling methods. This paper focuses on the importance of constitutive relationships and microstructure models in studying mechanical properties and optimizing structural design. The key issues concerning this topic and future directions for research are also discussed.

In order to study the conductive and microwave absorption performance of multi-dimensional multiphase filler conductive foam composites, carbon nanotubes (CNTs)/carbon black (CB)/polymethyl methacrylate (PMMA) nanocomposites with different porosity were fabricated via supercritical carbon dioxide (ScCO _2 ) one-step physical constraint foaming technology. The effects of filler component and porosity on the conductivity and absorbing properties of CNTs/PMMA/CB composite foam were studied. The Monte-Carlo method was used to study the percolation of composites and the effect of introduced microcells on the conductive network of multi-dimensional fillers. The results revealed that the volume conductivity of CNTs(3 vol%)/PMMA composites increased from 0.88 S m ^−1 to 3.31 S m ^−1 after the addition of 1 vol% CB. CNTs and CB had obvious synergistic effect on improving the conductivity of the composites, and the microwave absorption efficiency rose from 12.6 dB to 17.2 dB. With the increase of porosity, the electromagnetic wave absorption peak of CNTs/CB/PMMA composite foam moved to low frequency, while the conductivity showed a first rise and then a decline. The simulated percolation probability obtained by representative volume element (RVE) with different porosity also showed a similar trend, which turned out that with the increase of porosity, the effect of microcells on the convertion of conductive network construction from promoting to inhibiting.

A colloidal stability study of a nonaqueous silicon carbide suspension is of great significance for preparing special silicon carbide ceramics by colloidal processing. In this paper, three different chemical dispersants, which are amphiphilic, acidophilic, and alkaliphilic, are selected to compare their ability to stabilize nonaqueous slurries of silicon carbide. The analysis of the flow index factor is first used to estimate the colloidal stability of the suspensions. The results show that the addition of only 5 wt.% polyvinylpyrrolidone (PVP) forms a silicon carbide slurry with a low viscosity value of 17 mPas at 25 s−1. In addition, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS)measurements indicate that the PVP molecule is successfully adsorbed on the surface of silicon carbide. The different adsorption models are fitted, and the adsorption of PVP molecules on the surface of silicon carbide belongs to the Langmuir single-layer adsorption model. At the optimal PVP amount, the volume content of the suspension is as high as 22.27 vol.%, a Newtonian-like fluid still appears, and no agglomerate structure is formed in the system. After the volume content exceeds 22.27 vol.%, the flow index factor of the slurry begins to plummet, indicating that the slurry begins to transform from a Newtonian-like fluid to a shear-thinning fluid. The particles undergo inevitable agglomeration accompanied by the emergence of yield stress. Finally, a maximum solid loading of the system is predicted to be 46 vol.%, using the Krieger-Dougherty model.

In this study, we fabricated poly (methyl methacrylate) (PMMA) microcellular foams featuring tunable cellular structures and porosity, through adjusting the supercritical CO2 foaming conditions. Experimental testing and finite element model (FEM) simulations were conducted to systematically elucidate the influence of the foaming parameters and structure on compressive properties of the foam. The correlation between the cellular structure and mechanical properties was acquired by separating the effects of the cell size and foam porosity. It was found that cell size reduction contributes to improved mechanical properties, which can be attributed to the dispersion of stress and decreasing stress concentration.

This research presents an approach for C-O grain boundary strengthening of Al composites that used an in situ method to synthesize a C-O shell on Al powder particles in a vertical tube furnace. The C-O reinforced Al matrix composites (C-O/Al composites) were fabricated by a new powder metallurgy (PM) method associated with the hot pressing technique. The data indicates that Al4C3 was distributed within the Al matrix and an O-Al solution was distributed in the grain boundaries in the strengthened structure. The formation mechanism of this structure was explained by a combination of TEM observations and molecular dynamic simulation results. The yield strength and ultimate tensile strength of the C-O/Al composites, modified by 3 wt.% polyvinyl butyral, reached 232.2 MPa and 304.82 MPa, respectively; compared to the yield strength and ultimate tensile strength of the pure aluminum processed under the same conditions, there was an increase of 124% and 99.3%, respectively. These results indicate the excellent properties of the C-O/Al-strengthened structure. In addition, the strengthening mechanism was explained by the Hall−Petch strengthening, dislocation strengthening, and solid solution strengthening mechanisms, which represented contributions of nearly 44.9%, 15.9%, and 16.6% to the total increased strength, respectively. The remaining increment was attributed to the coupled strengthening of the C and O, which contributed 20.6% to the total increase.

Investigating the constitutive relationship of a material can provide better understanding of the mechanical properties of a material and has an irreplaceable effect on optimizing the performance of a material. This paper investigated a constitutive model for tungsten/polymethyl-methacrylate (W/PMMA) composite microcellular foams prepared by using melt mixing and supercritical carbon dioxide foaming. The stress-strain relationships of these foams with different W contents were measured under static compression. The elastic modulus and compressive strength values of the foams were remarkably greater than those of the pure PMMA foams: at a W content of 20 wt %, these values were increased by 269.1% and 123.9%, respectively. Based on the Maxwell constitutive model, the relevant coefficients were fitted according to the experimental data of different relative densities and W contents in quasi-static compression. According to the numerical relationships between the relevant coefficients and the relative densities and W contents, the quasi-static mechanical constitutive model of W/PMMA composite microcellular foams with W contents of 0~60 wt % and relative densities of 0.15~0.55 were predicted. This study provided basic data for the optimal design of the W/PMMA composite microcellular foams and proposed a method for investigating the mechanical properties of composite microcellular foam materials.

Direct-current magnetron sputtering (DCMS) was applied to prepare vanadium (V) films on Si substrate. The influence of substrate temperature (Ts) and target⁻substrate distance (Dt⁻s) on phase structure and surface morphology of V films were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscope (AFM) and transmission electron microscopy (TEM). The results show that the crystallinity of the V films increases with increasing Ts and decreasing Dt⁻s. The film deposited at Ts = 400 °C and Dt⁻s = 60 mm exhibits the best crystallinity and preferred orientation with a regular tetrahedral surface morphology. Oxidation behavior of the V thin films has also been studied by X-ray photoelectron spectroscopy (XPS).

In this paper, titanium matrix composites with in situ TiB whiskers were synthesized by the plasma activated sintering technique; crystalline boron and amorphous boron were used as reactants for in situ reactions, respectively. The influence of the sintering process and the crystallography type of boron on the microstructure and mechanical properties of composites were studied and compared. The densities were evaluated using Archimedes’ principle. The microstructure and mechanical properties were characterized by SEM, XRD, EBSD, TEM, a universal testing machine, and a Vickers hardness tester. The prepared composite material showed a high density and excellent comprehensive performance under the PAS condition of 20 MPa at 1000 °C for 3 min. Amorphous boron had a higher reaction efficiency than crystalline boron, and it completely reacted with the titanium matrix to generate TiB whiskers, while there was still a certain amount of residual crystalline boron combining well with the titanium matrix at 1100 °C. The composite samples with a relative density of 98.33%, Vickers hardness of 389.75 HV, compression yield strength of up to 1190 MPa, and an ultimate compressive strength of up to 1710 MPa were obtained. Compared with the matrix material, the compressive strength of TC4 titanium alloy containing crystalline boron and amorphous boron was increased by 7.64% and 15.50%, respectively.

NiO-based materials hold great promise as oxygen evolution reaction (OER) catalysts owing to their high intrinsic OER activity and good chemical stability. Herein, Ni/NiO/C hollow microspheres with high activity were successfully fabricated through a facile one-step mist chemical vapor deposition (mist-CVD) process using ethanolamine and nickel chloride as precursors. The high-temperature pyrolysis of the organic precursor yields a significant quantity of gas, leading to a rapid increase in pressure within the droplet, which prompts the nanoparticles to aggregate on the surface of the droplet and form a hollow structure. The crystal phase and morphology of the samples can be modulated through optimizing the decomposition temperature, and particularly, Ni/NiO/C porous hollow microspheres synthesized at 600 °C (Ni-600) presented the best OER activity, exhibiting an overpotential at 10 mA cm−2 (η10) of 286.4 mV and a Tafel slope of 54.8 mV dec−1. The outstanding OER electrocatalytic performance of Ni/NiO/C hollow microspheres is ascribed to the improved electronic conductivity facilitated by the existence of metallic Ni and amorphous C, coupled with the relatively large specific surface area derived from the unique hollow structure. [ABSTRACT FROM AUTHOR]