Journal of Materials Science最新文献

O significantly affects the thermal/stress-induced products in β-type titanium alloys. However, the mechanism of O effects on the displacive behaviors involved in the thermal/stress-induced phase transformation and twinning process is still not fully elucidated. The effects of interstitial O on specific orientation moduli and thermal/stress-induced products in bcc Ti–Mo alloys were investigated through first-principles calculations combined with microstructural observations. The addition of O decreased the formation energy of the supercell and formed the Mo–O and Ti–O bonds with the increase in the bonding electron number, thereby enhancing the β phase stability. The specific orientation moduli such as Young’s modulus (E₁₀₀), tetragonal shear modulus (C′), and shear moduli (G₁₁₁ and G₁₁₃) were increased, which was attributed to the formation of Mo–O and Ti–O bonds along <100>_β direction and the strengthened Ti–Ti bonds along <110>_β, <111>_β and <113>_β directions, respectively. The addition of O suppressed the thermal-induced ω phase, corresponding to its structural change from hexagonal to tripartite, and the predominant stress-induced product of α" martensite was inhibited due to the increase in moduli of G₁₁₁, C′, and E₁₀₀. This study deepens the understanding of the role of O in phase transformation and twinning mechanisms.

Sustainable renewable energy sources play significant role to encounter the unpredictable effects of climate change and energy deficit. Renewable energy holds great potential to mitigate environmental pollution issue brought on by the combustion of fossil fuels. Hydrogen (H₂) is a clean energy storage and carrier medium that can provide the highest energy density (142 kJ/g) without carbon emissions. Water splitting is a viable method to produce hydrogen (H₂) gas. This approach involves two important electrochemical processes: hydrogen evolution reaction at cathode and oxygen evolution reaction at anode. Water splitting towards hydrogen is highly energetic and requires efficient catalysts. Recently, nanostructured electroactive materials have attracted research attention due to their morphology, composition, and accessible active sites. Several nanostructured materials have been reported as promising catalysts and electrode materials in electrochemical water splitting. Even though water splitting with the use of nanomaterials is progressing, there are still drawbacks, including low stability, high cost, low durability, and insufficient efficiency. Therefore, the area is open for further investigation in synthesis and utilization of nanostructured electroactive materials with enhanced rate of charge transfer, reasonable bandgap and extended stability. Finally, the review highlighted challenges and future perspectives on the potential of electroactive nanomaterials for hydrogen production.

Graphical Abstract

Heterostructures composed of transition metal dichalcogenides (TMD) monolayers hold great promise in structural superlubricity. Recently, NbS₂ has been synthesized and its potential as the solid lubricant has been demonstrated. In this study, high-throughput first-principles calculations were conducted to investigate the friction behavior of four NbS₂ based heterostructures: NbS₂/TiS₂, NbS₂/MoS₂, NbS₂/NbSe₂, and NbS₂/MoSe₂ heterostructures, aiming to discover novel superlubricants. Among these, the sliding energy barrier and lateral shear strength of NbS₂/TiS₂ and NbS₂/MoS₂ heterostructures are the highest and lowest, respectively. The low bonding strength, differential charge density, and large in-plane stiffness of NbS₂/MoS₂ heterostructures result in lower frictional forces and friction coefficients under various normal loads. Furthermore, under the load of 1nN, the friction coefficient (0.0011) at the interface of NbS₂/MoS₂ heterostructure approaches the superlubricity threshold of 0.001, highlighting its superlubricity. Additionally, it has been proven that the Moiré superlattice formed by interlayer distortion can effectively reduce interlayer friction, and the sliding energy barrier of the rotating NbS₂/TiS₂ and NbS₂/MoS₂ heterostructures is reduced to about 1/100 and 1/500 of the initial heterostructure, respectively. These predictions underscore the potential of NbS₂/MoS₂ heterostructures as promising candidates for atomically thin solid lubricants.

This study investigates the effects of different annealing parameters on the microstructure, texture, and mechanical properties of hot-rolled pure yttrium plates using electron backscatter diffraction for the first time. With the increase of annealing temperature and time, the volume fraction of low-angle grain boundaries of hot-rolled pure yttrium plate decreases. While the intensity of the texture firstly decreases and then increases. During annealing at 600 °C, the {0002} pole density shifted from deviating from the normal direction (ND) by ~ 30° to being in line with the ND as the annealing time increased, forming a typical basal texture. This can be attributed to its unique recrystallization mechanism. The strength and hardness of the as-annealed samples were significantly lower than that under the hot-rolled state, while the elongation increased when compared with the hot-rolled sample. The considerable mechanical properties of pure yttrium plate are obtained by hot rolling and following annealing at 600 °C for 1 h.

In this study, a ternary Fg-C₃N₄/Ag₃VO₄/Fe₂TiO₅ nanocomposite with dual heterojunctions was successfully synthesized via a facile chemical precipitation method and evaluated for its effectiveness in photocatalytic CO₂ conversion. Extensive characterization techniques, including XRD, SEM, EDS mapping, TEM, XPS, UV–Vis DRS, were applied to explore the nanocomposite’s physicochemical properties and to elucidate the reaction mechanisms. The Fg-C₃N₄/Ag₃VO₄/Fe₂TiO₅ nanocomposite exhibited a significant enhancement in CO₂ conversion performance, particularly for CH₄ production. The optimized CH₄ yield reached 528.4 μmol/g-cat, representing a 4.3-fold and 2.4-fold increase compared to pristine Fg-C₃N₄ and Ag₃VO₄₅, respectively. Moreover, the composite photocatalyst demonstrated excellent stability and recyclability, retaining its efficiency over four successive cycles. The dual heterojunctions played a crucial role in enhancing the separation of photogenerated electron–hole pairs while minimizing recombination. This work offers valuable insights into the development of advanced photocatalysts with dual heterojunctions, presenting a promising approach for the efficient production of high-value products such as CH₄.

The poor hot workability of Cu-Ti alloys has become a bottleneck restricting the further improvement of properties and applications. In this work, the coupling effects of grain structure, precipitates and solid solubility on the hot deformation behaviors of Cu-3.18wt%Ti alloy were deeply studied. Our results show that based on the obtained constitutive equation and thermal activation energies, the corresponding hot workability maps of alloy can be established and used to guide the designation of hot working process. The complex interactions that occur between dislocation and precipitates lead to the differences in dynamic recrystallization (DRX) and precipitation for the changed strain rates and temperatures. The deformability can be improved by coupling control of DRX and dynamic precipitation. The corresponding mechanisms of hot deformation and microstructural evolution of grain structure, precipitates and solid solubility of Ti in the matrix during the hot deformation has been put forward. Our results provide fundamental insight into the DRX, precipitation and coordinated deformation of Cu-Ti alloys with poor deformability, as a function of hot strain.

Electron backscatter diffraction (EBSD) is used to determine the orientations of crystals on sample surfaces. In conjunction with the surface topography from atomic force microscopy (AFM), the facets of the crystals can be computed. Reconciling the coordinate systems of the EBSD and AFM measurements is a challenging and time-consuming process for rough polycrystal surfaces. This paper presents a novel method for importing EBSD data into the AFM coordinate system with minimal user input. This method proceeds by simulating EBSD band contrast images from the AFM topography. Then, a mapping between this simulated and the measured EBSD band contrast image is established by least-squares fitting. With this mapping, the EBSD data are projected onto the AFM coordinate system. In addition to automatic facet type determination, this enables a statistical analysis of the relation between the orientation and surface morphology of individual crystals on polycrystal surfaces. As an application example we analyze etched copper surfaces that are obtained in intermediate steps of the production of printed circuit boards (PCBs). Based on about 150 crystals, the analysis reveals a characteristic dependence of roughness and surface features such as ridges and etch hillocks on the crystal orientation.

Carbon nanomaterials have generated significant interest across various research fields, with catalytic graphitization emerging as a persistent topic within the carbon family. Graphitic carbon derived from carbon dots exhibits considerable potential for applications in energy storage devices. This study discusses the critical factors influencing the formation of nanosized carbon dots during the catalytic graphitization process, as well as the relationship between the degree of graphitization and lithium-ion storage performance. The results indicate that an increased sintering temperature, reduced particle size, and the incorporation of catalysts are advantageous for enhancing the degree of graphitization. A higher degree of graphitization is associated with a lower irreversible capacity loss for lithium ions, improved plateau capacity, and extended cycling stability at low current densities. This work offers valuable strategies for regulating both the degree of graphitization in nanocarbons and their corresponding lithium-ion storage capacities.

In the development of high-performance composite materials, metal-polymer heterogeneous structures are critical components due to their unique combination of metallic strength and polymer matrix flexibility. However, the lack of systematic analysis of metal surface treatment methods in these structures presents a significant challenge. Here we address this gap by providing a comprehensive review, beginning with an overview of the importance of metal-polymer heterogeneous structures and the current lack of systematic analyses regarding surface treatment methods. We first explore the fundamental principles underlying interfacial bonding mechanisms, focusing on mechanical interlocking, chemical bonding, and wetting theory. Then we meticulously discuss three prominent surface treatment techniques: sandblasting, chemical etching, and anodic oxidation. These techniques are analyzed for their efficacy and the mechanisms by which they generate micro-nanostructures on metal surfaces. The analyzation reveals that the micro-nanostructures induced by these treatments play a pivotal role in enhancing wettability and mechanical interlocking at metal-polymer interfaces, thereby significantly improving interfacial bond strength and durability. This review lays the groundwork for the theoretical foundation of interfacial design in metal-polymer heterogeneous materials, while also paving the way for novel research directions and technological advancements for the manufacture of composite materials with exceptional performance.

Graphical abstract

This study investigates the enhancement of interface properties in metal-polymer composites through advanced surface treatments.