Journal of Materials Science最新文献

Cracking susceptibility is a complex issue which has been extensively investigated for decades using both experimental and theoretical methods. In this study, cracking susceptibility in dissimilar aluminum alloy resistance spot welding (RSW) joints was investigated using thermodynamic simulations for three material combinations of aluminum alloys: 2195/5A06, 2195/2A14 and 2195/2219. The susceptibility to cracking was predicted using the maximum |dT/d(f_S)^1/2| up to (f_S)^1/2 = 1 as the crack susceptibility index. For each material combination, the hot cracking susceptibility (HCS) index values were calculated according to the Kou’s criterion. HCS curves and maps were constructed based on the calculation results. The predicted susceptibility followed the order: 2195/5A06 > 2195/2219 > 2195/2A14. Experimental results showed no obvious cracks in any of dissimilar Al alloys RSWed joints. In addition, factors such as cooling rate and residual stress may influence crack formation. Therefore, these factors should be considered to enhance the accuracy of the predictions for dissimilar Al alloy RSWed joints.

The ductile-to-brittle transition (DBT) of Ti-Nb-V multi-principal component alloys (MPEAs) was studied by combining experimental and molecular dynamics (MD) methods. The correctness of the selected potential function was verified through quenching simulation. Combined with transmission electron microscope, the stacking fault energy (SFE) values of Ti-Nb-V samples at different temperatures were measured and calculated. The microstructure in the process of crack initiation and propagation in the alloy system was discussed. The dependences of the length and density of different types of dislocations on temperature were calculated, and the effect of dislocations on the behavior of DBT was analyzed. The effects of critical energy release rate and fracture stress on DBT were studied. The critical transition point of DBT was determined. The accuracy of the DBT temperature (DBTT) obtained by MD method is evaluated by comparing the simulation results with the experimental results. The research in this paper deepens the understanding of DBT phenomenon of MPEAs, expands the nanoscale analysis method of dynamic cracking of alloy, and provides favorable theoretical support for optimizing material design.

Ideal double-layer capacitor electrodes require both high specific surface area and a porous structure efficiently wetted by electrolyte ions. Therefore, precisely controlling the pore structure of porous carbon materials to synergistically enhance both specific surface area and ion transport efficiency has become a key research challenge. This study employs lignin as a renewable carbon source, utilizing a templating approach to controllably synthesize hierarchical porous carbon materials. It systematically investigates the effects of single MgO hard templates, MgO-P123 dual templates, and single P123 soft templates on material structure and electrochemical performance. The MgO templating agent primarily contributes macropores/mesopores, enhancing ion transport and structural stability; the P123 templating agent mainly contributes mesopores, providing an efficient transport network and high specific surface area; the MgO and P123 dual-templating agents synergistically construct a multi-level pore structure comprising micropores, mesopores, and macropores. The ELCP-0.25 porous carbon prepared using P123 exhibits a high specific surface area and hierarchical porous structure, demonstrating outstanding performance in electrochemical energy storage applications. Within a three-electrode test system, this material displays exceptional electrochemical properties in KOH electrolyte, achieving a specific capacitance of 430 F/g at a current density of 1 A/g. Based on ELCP-0.25, symmetrical supercapacitors assembled with KOH and Et₄NBF₄/PC as electrolytes exhibit high specific capacitance and excellent cycle stability of 343 F/g and 161.84 F/g, respectively, with capacitance retention rates of up to 99.33% and 76.64% after 10,000 charge–discharge cycles. This work demonstrates the advantages of the template method in constructing hierarchical porous carbon materials, providing an effective technical approach for converting biomass waste into electrode materials for energy storage devices.

Hydrogen embrittlement (HE) remains a critical challenge in materials engineering, particularly for metals and alloys used in hydrogen fuel cell technologies. This review identifies the underlying problem of mechanical degradation caused by hydrogen–metal interactions, which compromise the ductility, toughness, and structural reliability of these materials. The study focuses on reviewing the main mechanisms of HE—namely Hydrogen Enhanced Local Plasticity (HELP), Hydrogen Enhanced Decohesion (HEDE), and the Hydrogen Pressure Theory—and their relevance to energy applications. A systematic review approach was adopted, integrating findings from experimental, theoretical, and computational studies to analyze how microstructural features and environmental factors influence susceptibility to HE. The review covers key experimental techniques such as Thermal Desorption Analysis (TDA), Atom Probe Tomography (APT), and in situ Scanning Electron Microscopy (SEM), which have advanced the understanding of hydrogen behavior in metals. Findings indicate that microstructural control and alloy design significantly affect hydrogen trapping and fracture behavior. Based on these discoveries, the study recommends the development of hydrogen-tolerant materials through microstructure optimization and advanced surface engineering. In conclusion, the review provides a comprehensive framework for mitigating HE in emerging hydrogen energy systems, promoting safer and more durable materials for sustainable energy applications. These findings not only identify key research priorities for advancing fundamental understanding of hydrogen–metal interactions but also offer practical guidance for designing hydrogen-tolerant alloys and improving the reliability of materials used in fuel-cell and hydrogen-energy systems.

The development of multifunctional nanomaterials for renewable energy and environmental remediation has accelerated in response to growing sustainability demands. However, many single-component systems face limitations such as poor charge separation and low catalytic efficiency. To overcome these challenges, we present the hydrothermal synthesis of a novel molybdenum disulfide–zinc sulfate–multi-walled carbon nanotube (MoS₂–ZnS–MWCNT) nanocomposite that integrates the layered structure of MoS₂, the photocatalytic properties of ZnS, and the high conductivity of MWCNTs. This ternary composite was systematically investigated for its dual functionality in the oxygen evolution reaction (OER) and photocatalytic dye degradation. Structural and morphological characterizations (X-ray diffraction, Field emission scanning electron microscopy, Transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy) confirmed successful hybridization and uniform distribution of the components. Superior electrocatalytic activity was demonstrated by a low overpotential of 392 mV at 10 mA cm⁻² and a Tafel slope of 99.5 mV dec⁻¹. This enhanced performance, coupled with a high electrochemical surface area (47.5 mA cm⁻²), points to significantly improved reaction kinetics and a greater abundance of accessible active sites resulting from synergistic interactions. Under simulated sunlight, the composite efficiently degraded Amido Black 10B, outperforming many binary and pristine materials reported in the literature. These findings suggest that the MoS₂–ZnS–MWCNT nanocomposite is a promising multifunctional catalyst with potential applications in water splitting and wastewater treatment, addressing a crucial need in integrated energy–environmental technologies.

In the paper, the cBN/NCD (nano-crystalline diamond/cubic boron nitride) multilayer coatings with varying modulation ratios (defined as the thickness ratio of NCD to cBN layers) were fabricated via alternating deposition of NCD and cBN layers. The microstructure and mechanical properties of cBN/NCD multilayer coatings were systematically characterized as a function of modulation ratio. The prepared coatings are dense and the thickness is uniform. Residual stress are compressive stresses in all coatings, and have a significant reduction as the modulation ratio increased. Fracture toughness shows a gradually increasing trend. The bonding strength between the coatings and substrates are significantly enhanced. When the modulation ratio is increased to 7:3, residual compressive stress is only 0.43 GPa and the fracture toughness rises to 4.98 MPa m^1/2. The reason for improvement of fracture toughness is attributed to the increased number of interfaces and higher NCD proportion, which can inhibit crack propagation and effectively prevent coating delamination. Besides, although the friction coefficient increases slightly, the wear resistance were significantly improved and the wear rate is as low as 1.19 × 10⁻⁶ mm³/N m. The research results will provide a theoretical basis for the preparation and industrial application of high-performance cBN coating tools.

This study investigates the geometrical, electronic, and optical properties of novel T-AlN monolayer using density functional theory calculations. The T-AlN nanosheet is confirmed to be a stable semiconductor, as evidenced by its negative cohesive energy, phonon frequencies, and a calculated bandgap of 2.897 eV. The interaction of toxic gases, CO, CO₂, NO, NO₂, and SO₂, with both pristine T-AlN and P-doped T-AlN (T-AlN (P_N)) nanosheets was systematically analyzed to evaluate their adsorption behavior. The results reveal favorable gas–surface interactions, with adsorption energies ranging from − 0.006 eV to − 2.674 eV. Both T-AlN and P-doped T-AlN nanosheets exhibit peak sensitivities of 2.16 × 10²⁴ and 5.69 × 10²¹, respectively, toward NO and NO₂ gases at 300 K. The adsorption mechanism is energetically favorable, as evidenced by negative adsorption energy values, signifying an exothermic and thermodynamically stable process that promotes spontaneous interaction between the gas molecules and the nanosheet surfaces. Work function analysis indicates the highest values upon NO₂ adsorption and the lowest for CO. Despite these changes, the associated deformation energies remain low (10⁻⁴ to 10⁻² eV), suggesting that the structural integrity of the sheets is largely preserved. These findings highlight the potential of T-AlN and P-doped T-AlN nanosheets as effective candidates for toxic gas sensing applications.)

Nickel-aluminum bronze (NAB) alloy is a potential candidate for marine applications due to its high corrosion and wear resistance. However, the as-cast defects and severe water turbulence affect the service life of the NAB alloy components. The current study addresses the same by surface modification of NAB by a facile electrochemical deposition technique. A ternary CuCoNi alloy was electrodeposited to enhance the service life of the NAB in marine environments. The coatings were deposited at different pHs of the electrolyte, namely 2.2, 2.5, 3.0, and 3.5. The effect of electrolyte’s pH on the structural, morphological, wettability, and corrosion properties of the CuCoNi alloy coatings was further explored. All the deposited coatings were nanocrystalline with an FCC crystal structure, exhibited hydrophobicity, and showed better corrosion resistance than the NAB substrate. Among them, the coating deposited at pH 2.2 showed the lowest corrosion rate of 2.67 µA/cm², the highest polarization resistance of 7.07 kΩ/cm², the lowest porosity of 0.054%, and the highest water contact angle of ≈ 150°. The high corrosion performance of this coating was due to its lowest wettability and near superhydrophobicity, lowest porosity, and uniformly distributed fine, dense particles in its surface morphology.