Journal of Materials Science最新文献

To investigate the effects of temperature and punch speed on the high-temperature bending behavior of rolled magnesium alloy plates, 150° bending tests were conducted under different conditions. The results indicate that at 573 K and a punch speed of 10 mm/min, tensile twinning in the inner region is significantly reduced, while the Schmid factor distributions of various slip systems in both the inner and outer regions become comparable, reflecting a mitigated tension—compression asymmetry. Under the condition of 523 K and 10 mm/min, the inner and outer regions exhibit the highest recrystallization fraction, the highest proportion of high-angle grain boundaries, and the lowest density of geometrically necessary dislocations, suggesting an optimal plastic deformation capability. In addition, static recrystallized grains retaining recrystallization characteristics are observed in the microstructure. The orientation disparity between these grains and the unrecrystallized grains exerts a pronounced influence on the overall texture: in the inner region, the large orientation difference leads to significant texture weakening (most evident at 573 K-10 mm/min), whereas in the outer region, the smaller orientation difference results in a relatively strong overall texture.

The influence of η-phase quench-induced (Q-GBPs) and age-induced (A-GBPs) grain boundary precipitates on hydrogen environment-induced cracking (H-EIC) in AA7085 high-strength Al–Zn–Mg–Cu aluminium alloy was investigated. GBP composition, size, density, and area fraction were systematically varied by adjusting the quench rate (6–200 °C s⁻¹) after solution treatment. High cooling rates (200 °C s⁻¹) suppressed Q-GBP nucleation, producing uniform A-GBP coverage after T76 ageing. Low cooling rates (6 °C s⁻¹) generated coarse, widely spaced Q-GBPs with higher Cu content and solute-denuded zones, with A-GBPs forming in the intervening regions. Medium cooling rates (40 °C s⁻¹) produced numerous finer Q-GBPs, reducing the overall A-GBP fraction. The effect of these distributions on H-EIC stages: crack initiation, short crack growth, and long crack growth, was deconvoluted using in situ optical monitoring of four-point bend tests in humid air (50% relative humidity, 70 °C). High cooling rates (200 °C s⁻¹) led to rapid initiation and a tenfold increase in crack growth rates compared to low cooling (6 °C s⁻¹). At 40 °C s⁻¹, initiation time (40 h) was similar to the low cooling condition, but the crack growth rate increased fivefold, remaining below that of the high cooling rate. These findings highlight the highly reactive nature of age-induced grain boundary precipitates markedly increased the susceptibility to H-EIC, whereas coarse, dendritic Q-GBPs with precipitate-free regions and reduced A-GBP coverage mitigate it. Overall, the results underscore that unambiguous identification of the grain boundary precipitate origin is crucial for accurately assessing the EIC performance of these alloys.

Using CO₂ as an active material for energy storage is an innovative approach for developing Li–CO₂ batteries. Despite the tremendous potential of Li–CO₂ batteries, their practical deployment is constrained by slow kinetics (leading to high overpotentials) and poor cycle life, primarily due to the sluggish decomposition of the discharge product, Li₂CO₃. To overcome the challenges associated with Li–CO₂ batteries, we synthesized electrospun polyacrylonitrile (PAN)-derived carbon nanofibers (CNF) via electrospinning. The synthesized CNFs were then subjected to hydrothermal treatment for synthesizing hierarchical metallic ruthenium (Ru)-anchored carbon nanofibers (CNF–Ru) for use as a cathode electrocatalyst in Li–CO₂ batteries. The CNF–Ru composite-based cathode exhibited a large specific surface area with numerous catalytically active sites, enhancing reaction rates and efficiency. The Li–CO₂ cell fabricated utilizing the CNF–Ru composite-based cathode exhibited an impressive and consistent charge–discharge performance over 191 cycles at a cutoff capacity of 500 mAh g^–1. To elucidate the origin of this enhancement, first-principles calculations were performed. The calculations revealed that nitrogen in the carbon support critically modulates the electronic structure of the Ru active sites, shifting the d-band center upward toward the Fermi level. This upshift enhances the intrinsic reactivity of the catalyst, facilitating the decomposition of Li₂CO₃ and providing a robust theoretical basis for the observed reduction in charge overpotential and improved cycling stability. This study, combining experimental evidence with theoretical validation, demonstrates the potential of hierarchically structured CNF–Ru nanocomposites for designing high-performance Li–CO₂ batteries.

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Heavy metal ions (HMIs) pollution poses severe threats to ecological integrity and human health, necessitating the development of sensitive, cost-effective, and matrix-adaptable detection technologies. Carbon quantum dots (CQDs) and their composites have emerged as promising candidates for HMI detection, owing to their exceptional optical properties, high stability, and excellent biocompatibility. In this study, we report a facile, cost-effective, and green synthesis route for the fabrication of red-emitting (R-CQDs) and green-emitting (G-CQDs) carbon quantum dots. These materials were systematically evaluated for the sensitive and selective detection of Hg²⁺, Ag⁺, and Cu²⁺ ions in both aqueous and saliva samples, thereby addressing critical needs in environmental monitoring and non-invasive health assessment. The detection performance was quantified using both ultraviolet–visible (UV–Vis) absorption spectroscopy and fluorescence (FL) spectroscopy. UV–Vis spectroscopy measurements revealed a limit of detection (LOD) of 50 nmol/L for Hg²⁺ at 235 nm (using G-CQDs), 100 nmol/L for Ag⁺ at 226 nm (using G-CQDs), and 5 nmol/L for Cu²⁺ at 215 nm (using R-CQDs). Fluorescence spectroscopy further demonstrated LODs of 250 nmol/L for Hg²⁺ and 5 µmol/L for Ag⁺ (both at an excitation wavelength of 480 nm using G-CQDs), and 0.5 µmol/L for Cu²⁺ at an excitation wavelength of 427 nm (using R-CQDs). Collectively, our findings demonstrate that the as-synthesized R-CQDs and G-CQDs exhibit high sensitivity and selectivity toward target HMIs. Their successful application in real water and saliva samples underscores their significant potential for practical environmental monitoring and personal health screening.

This study experimentally investigates the fracture and damage characteristics of different ceramic targets under impact loading. The research finds that radial cracks form during the loading phase and extend during unloading, appearing earlier than circumferential cracks. The introduction of a steel backing plate enhances the stiffness of the target, inhibiting the generation of circumferential cracks but not altering the stress state on the front face of the ceramic. Micro-fracture mode analysis indicates that Al₂O₃ exhibits intergranular fracture characteristics, while B₄C shows trans-granular fracture characteristics, and SiC exhibits both fracture modes. In terms of crack propagation dynamics, the path of conical cracks is regulated by both the internal stress field within the ceramic and the reflected tensile pulses, with the cone angle being independent of impact velocity but significantly influenced by ceramic thickness and material properties. Specifically, the radial crack propagation in Al₂O₃ behind the formation of the fractured cone, whereas in SiC and B₄C, it is the opposite. It is noteworthy that the diameter of the perforation is only related to the size of the projectile head and the material’s shear strength, independent of thickness and impact velocity. Furthermore, the load variations among different ceramics at the same impact velocity are significantly different, primarily manifesting in the peak load and the dwell time of projectile. The study reveals the failure mechanisms and performance balance rules of different ceramic systems under dynamic loading, providing important theoretical basis for the optimization design of protective materials.

Based on the safety concerns and expected high-energy density, all-solid-state lithium batteries (ASSLBs) are in a good position to replace current lithium-ion batteries (LIBs). However, the technological evolution of electrode materials to contend with those of LIBs employing liquid electrolytes is still limited owing to the lack of functionality in terms of capacity retention, rate capability, and cycling endurance of cathode materials in ASSLBs. Two-dimensional (2D) transition-metal dichalcogenides show outstanding potential as cathodes in LIBs owing to their distinctive physiochemical properties. In this study, 2D WSe₂ is prepared via solution phase method followed by sintering route and is further used as cathode material in ASSLB (Li/75%Li₂S-24%P₂S₅1%P₂O₅/Li₁₀GeP₂S₁₂/WSe₂). WSe₂ demonstrates a substantial reversible capacity of 309.3 mAh g⁻¹ following 400 cycles at 100 mA g⁻¹, whereas the ASSLBs maintain an impressive gravimetric energy density of 447.3 Wh kg⁻¹ along with volumetric energy densities of and 651.2 Wh L⁻¹, over the same cycling period. The endurance of very long cycles is attributed to the well-developed layered two-dimensional structure and good electronic conductivity of WSe₂. Additionally, the reaction mechanism, electrochemical reaction kinetics as well as capacity contributions are further analyzed.

This study aims to develop a superhydrophobic laser-induced graphene (LIG)-based composite coating with enhanced electrothermal and anti-icing properties. To address the inherent limitations of pristine LIG, fluorinated ethylene propylene (FEP) nanoparticles were uniformly dispersed in an electronic fluoride solution, spray-coated onto LIG, and annealed to form a three-dimensional micro-/nanostructured architecture. The resulting composite exhibited a water contact angle of 150.1° and extended the freezing delay time from 75 s for pristine LIG to 343 s, representing more than a fourfold improvement. Moreover, the electrothermal de-icing performance was significantly enhanced: under identical voltage conditions, the heating response time was reduced by a factor of 2 to 6, while the maximum achievable temperature increased by 1.5 to 2 times. Notably, the composite achieved rapid de-icing within a very short period and readily surpassed the temperature limits of pristine LIG. The coating maintained stable hydrophobicity after repeated de-icing cycles. This approach integrates superhydrophobicity, anti-icing capability, and thermal stability, offering a promising strategy for the design of LIG-based composites and providing valuable insights for applications in the aviation, automotive, and construction industries.

Micro-arc oxidation (MAO) is established as a leading surface protective technique for improving the wear resistance of aluminum alloys. This review focuses on the influences of electrical parameters, electrolyte composition, pre- or post-treatments, and service environments including dry and lubricated sliding, elevated temperatures, fretting, and tribo-corrosion on the tribological performance of aluminum alloy-based MAO coatings. Prior to summarizing the prevailing wear mechanisms, correlations among processing conditions, coating microstructures, and wear behavior were compared quantitatively. MAO coatings can enhance the surface hardness of the substrate by approximately 100–200%. Through electrolyte design, nanoparticle incorporation, and tailored pre- or post-treatments, the coefficient of friction under dry sliding conditions could be lowered from 0.5–0.8 to 0.1–0.3 while wear rates are reduced by one to two orders of magnitude. Additionally, special consideration is given to the effect of coating porosity, the integrity of the dense inner layer, and the role of composite or sealed structures in determining durability under complex loading conditions. Current limitations related to inherent porosity, scalable processing, and energy consumption are evaluated. Finally, emerging developments in intelligent manufacturing, energy-efficient MAO technologies, and multifunctional coatings are proposed. This review seeks to establish a quantitative, mechanism-oriented foundation for designing high-performance MAO coatings and to facilitate their expanded industrial adoption.

The mechanical properties and deformation mechanism of coaxial polycrystalline Ni with different misorientation angles (MA) under tensile load are simulated by molecular dynamics, focusing on investigating the activation mechanism of {111} < 112 > partial dislocation slip systems. It was found that under fixed load stress conditions, the orientation of grains is determined by the MA value, and the Schmid factor (SF) value also changes accordingly. The activation of dislocation slip systems is regulated by MA and SF, where the dislocations exhibiting lower MA and higher-SF values are preferentially activated. This activated dislocation slip system not only induces the nucleation and growth of stacking faults, but also facilitates stress transmission, further promoting the activation of other partial dislocations. Specifically, the polycrystalline Ni with a rotation angle of 50° exhibited the highest tensile strength and plastic deformation ability. The Lomer–Cottrell (L-C) locks formed by the interaction of partial dislocations from different slip systems or L-C locks due to the partial dislocations blocked by stacking faults, combined with the broadening of stacking faults by energy absorption, jointly strengthen polycrystalline Ni materials. These insights provide a data foundation and theoretical basis for the design and development of polycrystalline nickel for high-temperature alloys.