Journal of Materials Science最新文献

Electroless deposition (ELD) via spontaneous redox reactions between metal precursors and carbon substrates provides a sustainable and surfactant-free approach to supported metal nanoparticles (NPs). However, it is often limited by the weak reducing ability and cost of conventional carbons. Herein, we report a biomass-derived carbon (BC) prepared from microcrystalline cellulose (MC) as a low-cost carbon matrix that acts as both the reducing agent and the stabilizer for ELD of noble metals. Nitrogen (N)-doped biomass carbon (NBC) further improves deposition control, enabling tunable Pd loading, particle size, and dispersion with nitrogen content. Pd/NBC 5 shows an about threefold higher activity for 4-nitrophenol (4-NP) reduction than commercial Pd/C under identical conditions, mainly due to uniform Pd dispersion and nitrogen-enabled interfacial effects. Using the same procedure, NBC 5 also enables ELD of Au, Pt, and Ru with good dispersion, demonstrating the generality of this nitrogen-tunable biomass carbon. This work provides insights into how nitrogen tuning in biomass carbons regulates ELD behavior and offers a mild, aqueous, reductant-free strategy to construct carbon-supported noble metal nanocatalysts for chemical and environmental catalysis.

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TaC is considered as a promising material for extreme environments due to its excellent high-temperature performance. Molecular dynamics simulations are essential for elucidating atomic-scale mechanisms. However, no existing interatomic potential for TaC achieves both satisfactory accuracy and computational efficiency across a wide range of applications. In this study, we develop a deep learning interatomic potential for TaC based on a neural network framework to overcome these limitations. Compared to classical semi-empirical potentials and other deep learning-based models, the present potential demonstrates superior representability and transferability across a comprehensive set of properties, such as bulk properties, surface energies, grain boundary energies, generalized stacking fault energies, point defect formation energies, and melting point. All of these results are in good agreement with density functional theory calculations and experimental data. Extensive benchmark tests further confirm that the potential achieves a favorable balance between accuracy and computational efficiency. In addition, the stress–strain curves obtained at different temperatures reveal that increasing temperature leads to a reduction in yield strength and elastic modulus, while the corresponding yield strain remains nearly constant, except at 3000 K. Fracture dynamics and dislocation mobility analyses are performed to provide a comprehensive understanding of the tensile fracture mechanism, together with the influence of irradiation-induced vacancy clusters on dislocation mobility. The present potential is well suited for molecular dynamics simulations of TaC across a wide range of applications, particularly for studying deformation behavior in extreme environments.

PANI/PVA/EG composite hydrogels with excellent antifreeze performance at -18 °C and high flexibility were successfully fabricated via the in-situ polymerization of polyaniline (PANI) in a polyvinyl alcohol/ethylene glycol (PVA/EG) dual-network hydrogel matrix. This structured composite hydrogel displayed outstanding mechanical properties, with a maximum tensile stress of 0.45 MPa, an elongation at break of 455%, and complete shape recovery after 3000 cycles of 90° bending. It featured a rod-like nanofibrous structure and possessed an equivalent series resistance of 4.83 Ω, a discharge time of 43 s, and a specific capacitance of 107.5 mF/cm², thus exhibiting superior charge storage performance. Photosensitivity tests indicated that the hydrogel presented the strongest photoresponse to red light (700 nm) and the weakest to ultraviolet light (< 400 nm), endowing it with distinct wavelength-selective photosensitive properties. Moreover, the hydrogel maintained stable electrical signal responses upon stepwise tensile deformations of 14%, 28%, and 42% (with corresponding gauge factors (GFs) of 2.983, 4.385, and 3.601, respectively) and 3000 cycles of tensile testing at 28% strain, which attested to its high sensing sensitivity and excellent structural durability. In conclusion, the PANI/PVA/EG composite hydrogel, as a flexible sensor, integrates excellent electrochemical energy storage performance, superior mechanical flexibility, and favorable low-temperature adaptability, rendering it highly promising for practical applications such as real-time human motion monitoring in cold environments.

In this study, isothermal hot compression tests were conducted on solid-solution-treated novel Mg-3.3Gd-2.5Nd-0.4Zn-0.3Zr alloy across 370–490 °C and 0.001–1 s⁻¹ to establish reliable processing guidelines. Experimental flow stresses were modeled via a hyperbolic sine constitutive equation, while processing maps generated through the dynamic material model (DMM) identified two optimal thermomechanical windows: 370–490 °C and 0.001–0.03 s⁻¹, 430–490 °C and 0.03–0.37 s⁻¹. Microstructural analysis at ε=0.3 revealed discontinuous dynamic recrystallization (DDRX) as the dominant softening mechanism in stable regions. Adjacent to instability zones, concurrent DDRX and continuous dynamic recrystallization (CDRX) occurred with deformation twinning, accompanied by <0001>//CD texture evolution that suppressed basal slip. Transmission electron microscopy (TEM) observations demonstrated that dynamically precipitated second phases accelerated recrystallization via particle-stimulated nucleation (PSN), with finer and more abundant precipitates at 410 °C than at 450 °C.

This study examines the hot corrosion behavior of wrought and LPBF-manufactured 18Ni300 maraging steel, which serves as containment materials in concentrated solar power (CSP) plant applications. In this article, these samples are exposed to a salt mixture of NaCl (25 wt.%) and Na₂SO₄ (75 wt.%) at an operating temperature of 750 °C for 60 h. The corrosion kinetics have been revealed by the weight change method, and Fe₂O₃, Fe₃O₄, NiO, CoO, MoS₂, TiO₂, Fe₂Mo₃O₈ and spinel oxides such as NiFe₂O₄ and CoFe₂O₄ are formed at the surface. The oxide layers on the wrought 18Ni300 steel are porous and prone to spallation, leading to continuous exposure of fresh surfaces to hot corrosion. In contrast, the LPBF samples, with their controlled fine-grain cellular microstructure, large grain boundary, and high dislocation densities, exhibit a more homogeneous, less porous, and intact protective oxide layer, resulting in superior corrosion resistance. Furthermore, aged samples of both wrought and LPBF maraging steel, characterized by coarse grains and low dislocation density, are more susceptible to corrosion compared to their as-received counterparts. Notably, the additively manufactured LPBF samples consistently exhibit lower corrosion rates and therefore higher corrosion resistance than the wrought samples from the outset of exposure, attributable to their hierarchical microstructure and high dislocation density.

The magnetostriction effect of ferrite materials will adversely affect their application in high-precision electrical measurement scenarios. In this study, vanadium pentoxide (V₂O₅) was introduced as both a sintering aid and a dopant in the solid-state sintering process of iron-deficient NiCuZn ferrites with the composition (Ni₀.₂Cu₀.₂Zn₀.₆O)₁.₀₃(Fe₂O₃)₀.₉₇. The results show that the addition of V₂O₅ effectively promots grain growth, increasing the average grain size from approximately 1 μm to 6 μm, and enhances the compactness of the material, which would compensate the magnetization reduction due to the replacement of Fe³⁺ by V⁵⁺. When the doping concentration of V⁵⁺ is controlled below 3 at%, the magnetostriction strain of the ferrite can by minimized to approximately 8 ppm without significant loss of key magnetic properties such as permeability and saturation magnetization. In addition, vanadium doping also improved electrical resistivity of NiCuZn ferrite, thereby reducing eddy current losses and power loss of material under high-frequency (50 kHz and 100 kHz) electromagnetic fields, which make the V⁵⁺ doped NiCuZn ferrites possibly be used in the high-precision and high frequency measurement.

In this study, pulsed neutron Bragg-edge transmission (BET) imaging was employed to characterize plastic deformation of high-manganese (Mn) austenitic steel during cryogenic impact fracture. Electron backscatter diffraction (EBSD) was used to examine the microstructural evolution. The results reveal that the Bragg-edge width of the (200) lattice plane, σ₂₀₀ = 100 µs, was identified as the critical value for large plastic deformation. Accordingly, the characteristic regions were classified by σ₂₀₀ value. Regions with σ₂₀₀ > 100 µs correspond to crack initiation and stable crack growth, while those with σ₂₀₀ < 100 µs correspond to unstable crack growth. Both crack initiation and stable crack growth regions exhibited higher levels of plastic deformation, twin density, and dislocation density compared to unstable crack growth regions. Moreover, σ₂₀₀ showed strong positive correlations with the dislocation density, twin density and hardness. As the test temperature decreased from 273 to 77 K, the transition point from stable to unstable crack growth occurred earlier. This is responsible for the reduction in impact absorbed energy. These findings provide new insights into the cryogenic toughening mechanism of high-Mn austenitic steel.

To address the problem of insufficient toughness of carbon fiber (CF) reinforced thermosetting epoxy (EP) composites, a discontinuous fiber/thermoplastic PA12 particle co-toughened CF/EP composite laminate was designed in this paper to maximize its toughness while considering its high strength advantages. Firstly, inspired by the strong and tough biological structures in nature, a discontinuous fiber/interlayer toughened CF/EP laminate structure and its forming process were proposed. Secondly, a three-point bending (3 PB) finite element simulation of the discontinuous fiber laminate was conducted to investigate the influence of the discontinuous fiber structural parameters on the mechanical properties. The optimized design of the discontinuous fiber toughened laminate structure was hence carried out based on machine learning. Then, the interlaminar fracture toughness, interlaminar shear strength, and 3 PB tests of interlaminar toughened laminates were carried out to investigate the influence of the type of interlaminar toughened material and its density on the mechanical properties of the laminates. Finally, it was experimentally demonstrated that the discontinuous structure and interlaminar toughening method yielded a joint toughening effect.

The study investigates the common issue of prosthetic abutment screw loosening in implant dentistry, which is often caused by microgaps at the implant–abutment interface. Packing agents are typically used to mitigate microleakage. The research specifically examines the role of collagen doped with diamond-like carbon (HDLCC) nanofilms as packing gel, which could provide high wear resistance and reduced friction. However, their effectiveness and influence on the mechanical behavior of implant systems remain uncertain. The study analyzed three implant models, Nobel (NL), Straumann, (STRM), and WEGO (WO), with and without HDLCC coatings. The plasma-enhanced chemical vapor deposition method was employed to coat HDLCC nanofilm on the surface of the abutment screw. The study aimed to assess the effects of HDLCC coating on thread wear, torque loss of abutment screws, and microleakage within a simulated oral environment, involving a total of 30 samples. After subjecting abutments to a 30⁰ off-axis dynamic force of 20 to 200 N for 48 h, scanning electron microscopy and a ball-on-flat setup were used to evaluate morphologies and gel friction. Statistical analysis indicated that HDLCC coating reduced microleakage and increased optical density, particularly in STRM implants after 12 h of cyclic loading (P = 0.44). Moreover, torque loss was observed during tightening and increased under dynamic load across all groups, with STRM implants exhibiting the best antiloosening property (P < .001). The application of HDLCC gel decreased both initial (P = .048) and final torque loss rates (P = .032) in all systems.