Journal of Materials Science最新文献

In this paper, the aluminum nanofoam compression and shear deformation behavior are investigated using molecular dynamics (MD) simulations with emphasis on the dislocation-based underlying mechanism and temperature dependence. Nanofoam structures with controlled relative density are generated by Voronoi tessellation and simulated quasi-statically using the embedded-atom method (EAM) potential. The simulations determine distinct deformation behaviors: Compression has three consecutive stages—elastic response, plastic plateau via ligament buckling, and densification—and shear deformation has initial linear elasticity followed by nonlinear hardening and localized shear banding. Size effects at the nanoscale significantly enhance the yield strength, with compressive strength higher than shear strength by approximately 30–40%. Power-law scaling of stiffness and yield stress with relative density is confirmed, as predicted by Gibson–Ashby. Dislocation analysis indicates that plasticity begins by Shockley partial dislocation nucleation at pore walls, growing dense dislocation networks under compression but developing toward a steady state under shear due to efficient dislocation annihilation at free surfaces. Elevated relative density enhances the material’s strength and hardness and reduces ductility, whereas elevated temperature lowers strength and stiffness significantly due to thermally activated dislocation motion. These observations represent atomistic visions of structure–property relationships in aluminum nanofoams and offer design hints for optimizing strength–ductility balance in weight-efficient structural applications.

2324 Al alloy, known for its high strength, low density, and excellent corrosion resistance, is widely used in the lightweight field of aerospace and automotive. In this work, Mn-free 2324 Al alloy plates were prepared using powder metallurgy, followed by hot extrusion and T39 heat treatment. The effects of grain size, texture, and precipitation on the alloy’s anisotropy were systematically investigated. The mechanical properties along different directions of the 2324 Al alloy were evaluated, including the transverse direction (TD), extrusion direction (ED), and a 45° direction. The results revealed significant difference in mechanical properties due to microstructure variation, with higher tensile strength and yield strength in ED, while superior elongation was exhibited in the 45° direction. The difference is attributed to the crystal grain shape, precipitate distribution, and texture evolution. The study emphasizes the critical role of the S-phase (Al₂CuMg) in enhancing strength and plasticity through dispersion strengthening and grain boundary reinforcement. Additionally, recrystallization behavior and texture evolution, including the formation of Goss and cube textures, are found to significantly influence the mechanical performance. The findings provide a comprehensive understanding of the anisotropic behavior in the 2324 Al alloy and offer insights into optimizing the processing for industrial applications.

The advancement of sodium-ion batteries (SIBs) depends on designing high-performance anode materials. Hard carbon (HC) is a suitable candidate due to the availability and low cost of resources for production, but its limited reversible capacity and unsafeness upon high-rate charging remain obstacles. Herein, a novel simple strategy combining low-temperature pyrolysis and hydrothermal treatment for the fabrication of a synergistic composite based on hard carbon coated by molybdenum disulfide nanosheets has been developed. The MoS₂@HC composite shows superior electrochemical characteristics for SIBs in contrast with HC and MoS₂ on their own. In particular, it demonstrates almost two times better sodium storage ability at high current densities as compared to HC. The operating potential of the MoS₂@HC composite is higher than that of HC, implying improved battery safety. At the same time, the composite shows a better cycle life than MoS₂. It stays stable during long-term cycling, whereas MoS₂ shows unacceptable behavior already after the 100^th cycle. The resulting MoS₂@HC composite at low current density of 20 mA g^–1 delivers a reversible capacity stabilized at 304 mAh g^–1. It also demonstrates cycling stability at high current densities with a capacity of 131 mAh g^–1 over 200 cycles at 1000 mA g^–1. This research opens a facile way for designing hard carbon based anode for sodium-ion batteries with increased capacity and improved safety.

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Flexible stainless steel substrates (SS) were used to deposit reduced graphene oxide (rGO)/ molybdenum oxide (MoO₃) thin films by cost-effective chemical bath deposition (CBD) method varying rGO concentrations (1, 3, and 5 mg mL⁻¹). The influence of rGO incorporation on the structural and electrochemical properties of electrodes was investigated. The thin films of RMO2 (deposited at 3 mg mL⁻¹ rGO concentration) nanocomposites demonstrated a hexagonal crystal structure and nanoparticles like surface morphology. The presence of rGO in rGO/MoO₃ was confirmed by the Raman and EDS studies. RMO2 nanocomposite thin film exhibited 547 F g⁻¹ specific capacitance at current density of 2 mA cm⁻². The flexible RMO2//PVA-H₂SO₄//PANI asymmetric (ASC) device was assembled using RMO2 as a negative electrode and PANI as a positive electrode. The device showed a specific capacitance of 61.5 F g⁻¹ with energy and power densities of 14.4 Wh kg⁻¹ and 1.3 KW kg⁻¹, respectively, with 84.3% capacitive retention over 5,000 CV cycles.

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The wire arc additive manufacturing (WAAM) technology, by virtue of its unique processing flexibility, demonstrates remarkable applicability and advantages in the fabrication of complex magnesium alloy components. However, during the WAAM process, significant heat accumulation occurs, which leads to a coarse microstructure in the components, degrading their mechanical properties. In this study, an interlayer pause strategy was designed and applied to utilize the accumulated heat for tailoring the microstructure of the ZM5 (Mg–7.6Al–0.13Mn–0.63Zn, at.%) alloy. Six different interlayer dwelling times (0 s, 30 s, 60 s, 90 s, 120 s, and 180 s) were adopted. By precisely controlling the interlayer pause time, when it reaches 90 s, a sample with refined grains and an appropriate second-phase volume fraction was produced. This sample demonstrated a remarkable strength–ductility synergy, achieving a yield strength of 160 MPa, an ultimate tensile strength of 283 MPa, and an elongation of 30%. Among them, grain boundary strengthening is the primary strengthening mechanism. This approach of regulating mechanical properties through in situ thermal management could similarly be extended to diverse material systems and advanced manufacturing processes.

Reuse of dye-containing wastewater for valuable products offers significant potential. Chitosan, a natural high-molecular-weight porous material, served as an effective carrier for dye molecules. This study uses chitosan to adsorb Congo Red, preparing hierarchical porous carbon materials, which are then applied in supercapacitors. The findings reveal that chitosan achieves an impressive adsorption capacity of 1450 mg g⁻¹ for Congo Red. When the chitosan–Congo Red composite material-based carbon is used as the electrode material, it shows an outstanding specific capacitance of 318 F g⁻¹ at a current density of 1 A g⁻¹. Furthermore, due to its high content of heteroatoms such as N, O, and S, the double-layer supercapacitor fabricated with this electrode material demonstrates a specific capacitance of 149.49 F g⁻¹ at 1 A g⁻¹, with an energy density of 8.77 Wh kg⁻¹ at a power density of 335.35 W kg⁻¹. These results highlight the considerable potential of this material after adsorption of dye-containing wastewater for applications in the energy storage field.

To address the challenge of irreversible aggregation of nanocrystalline cellulose (CNC) after dehydration and to prepare high-concentration redispersible CNC pastes, this study presents an eco-friendly strategy employing maltodextrin (MD) and sodium polyacrylate (PAAS) as synergistic dispersants. MD functions as a “hydrogen bonding inhibitor” whereas PAAS effectively stabilizes CNC suspensions through electrostatic repulsion. Redispersible CNC pastes with varying dehydration levels were successfully prepared via vacuum-assisted concentration. Systematic evaluations of MD/PAAS impacts on Re-CNC colloidal behavior—including the hydrodynamic diameter, particle size distribution, and surface charge (zeta potential) unveiled the identification of four optimal redispersion pathways. Crucially, the concentration-dehydration-rehydration cycle preserved CNC’s intrinsic properties under optimized conditions. Transmission electron microscopy (TEM) analysis confirmed the morphological integrity of CNC, while Fourier-transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) profiles confirmed retention of chemical functionalities and crystalline structures. The engineered pastes exhibited prolonged dispersion stability (> 30 days without sedimentation). Thermal gravimetric analysis further revealed that MD-stabilized Re-CNC maintained thermal decomposition resistance equivalent to native CNC, with PAAS integration substantially elevating thermal endurance by 18–22%. Ultimately, using redispersed cellulose nanocrystals (Re-CNC) and sodium alginate (SA) as the matrix and curcumin (Cur) as the model drug, a double-network hydrogel, Cur@Re-CNC/SA, was constructed through cross-linking with calcium gluconate. Its drug release performance was comparable to that of Cur@CNC/SA prepared from pristine CNC, verifying the feasibility of the redispersion strategy.

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In hydrogen isotope storage materials crucial for achieving controllable nuclear fusion fuel supply, ZrCo alloys have become a promising candidate material due to their excellent performance. However, their hydrogenation kinetics are highly affected by gas impurities, particularly carbon monoxide (CO). In this work, by depositing a Pd film on the surface of Zr_0.8Ti_0.2Co and ZrCo alloy particles, the hydrogen absorption kinetics and cyclic stability of the alloy in different H₂/CO mixed atmospheres were systematically investigated. The changes in the microstructure and morphology of the samples during the cycling process were analyzed and discussed through various characterization methods and kinetic models. The poisoning effect of CO on Zr_0.8Ti_0.2Co alloy and the reasons for the improvement of sample detoxification performance and cycling stability by palladium film coating were analyzed. This work introduces a novel strategy for improving the poisoning resistance of ZrCo-based hydrogen isotope storage alloys.

The commercialization of sodium-ion batteries is contingent upon the development of low-cost, high-capacity anode materials exhibiting excellent cycling stability. In this study, bamboo powder was employed as a precursor for the synthesis of N, O co-doped porous bamboo-derived hard carbon (BCHC-N3), which demonstrated high cycling stability. Furthermore, the influence of morphological characteristics on capacity retention and cycling stability was systematically investigated. After modification, BCHC-N3 was engineered to possess abundant closed pores and a widened interlayer spacing. These structural attributes are considered beneficial for the rapid transport of Na⁺. The electrochemical data indicate that the BCHC-N3 anode demonstrated a significantly improved reversible capacity of 304 mAh g⁻¹ at 0.1 A g⁻¹, with a 184 mAh g⁻¹ increase in plateau capacity over the directly carbonized bamboo powder (BHC). Furthermore, remarkable cycling stability was demonstrated at a high current density of 1 A g⁻¹, where 77.14% capacity retention was maintained after 1,000 cycles. The sodium storage mechanism of BCHC-N3 was elucidated through the galvanostatic intermittent titration technique analysis, revealing a dominant “adsorption–insertion/filling” process, which thereby uncovers the origin of its superior performance. This work presents a straightforward approach for producing sodium-ion batteries with exceptional cycling stability.

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In this paper, we employed a strategy of structural regulation and N-doping to synthesize bamboo-derived porous hard carbon. This approach effectively enlarges the interlayer spacing and enhances the electrical conductivity of hard carbon, and N-doping improves defects and increases the number of Na⁺ storage sites, improving electrochemical performance of bamboo-derived porous hard carbon for sodium-ion batteries. Moreover, when porous hard carbon was used to assemble full cell, the cells demonstrated outstanding electrochemical performance.

Zinc-air batteries (ZABs) are regarded as promising energy storage devices next-generation, but it is limited by their sluggish oxygen reduction/evolution reactions (ORR/OER). Therefore, it is highly necessary to explore inexpensive and more efficient transition metal based electrocatalyst for facilitating OER and ORR. Consequently, in this paper, transition metal phosphating compounds (Co₂P₂O₇/FeP₂@C) was synthesized by high-temperature treatment CoFe terephthalic acid chelating with phytic acid (PA). The resulting nanostructures of Co₂P₂O₇/FeP₂ coated with P-doped carbon exhibit outstanding electrocatalytic performance, achieving OER overpotential of 405 mV at 10 mA cm⁻² and an initial ORR potential of 0.83 V versus reversible hydrogen electrode. Meanwhile, the ZABs prepared by Co₂P₂O₇/FeP₂@C exhibited high specific capacity (817.76 mAh g⁻¹) and long cycle stability (60 h). Here, the well-designed terephthalic acid unified with PA, not only produced phosphide at elevated temperatures, but also enhanced catalyst porosity caused by abundant hydroxyl groups in PA, potentially increased specific surface area. Additionally, PA introduced P-doped carbon matrix, which effectively modulated the carrier's electronic structure, introduced more defect as active sites and combined with porous structure to enhance the electrocatalytic effect. This work introduced an environmentally friendly method to synthesize transition metal phosphide on porous carbon matrix, and it is anticipated to find extensive applications in electrocatalysis.

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