A single‐source SiC/HfC‐containing precursor was synthesized using polysiloxane as a precursor and hafnium acetylacetonate (Hf(acac) 4 ) as a metallic modifier. Dense SiC/HfC composites were prepared via precursor pyrolysis combined with spark plasma sintering. The cross‐linking mechanism, microstructural phase evolution, and ablation resistance were systematically studied, and the role of Hf modification in enhancing oxy‐propane ablation resistance was revealed. Results show that the densification of the ceramics is significantly improved with Hf(acac) 4 content. After oxy‐propane ablation at 1600 °C for 120 s, the SiC/HfC composites modified with 20 wt% Hf(acac) 4 exhibit superior linear (0.008 µm/s) and mass ablation rates (−0.478 mg/s). Under high‐temperature ablation, HfC was oxidized into HfO 2 , which subsequently reacted with SiO 2 to form a dense HfSiO 4 layer. This oxide scale inhibits SiO 2 volatilization and oxygen diffusion, providing effective protection for the SiC matrix. This study provides a feasible route for fabricating high‐performance SiC‐based ultrahigh‐temperature ceramics for thermal protection systems.
Textile‐integrated sensors are investigated as functional elements in engineering textiles, enabling monitoring in deformable systems, including biomedical applications. While most current research focuses on material choice, mounting evidence shows that the textile architecture also plays a decisive role in affecting sensor stability and reliability. This study compares two textile architectures designed for sensor integration: a weft‐knitted pocket structure and a weft‐knitted tunnel‐routing structure. These architectures employ different sensor integration approaches, such as embroidered capacitive sensors and braided sensor yarns, which reflect their respective structural integration strategies. The integrated textile samples were subjected to tensile, bending, and compressive loads, as well as thermal sterilization and exposure to chemical environments relevant to wound care applications. Under these conditions, the two textile architectures exhibited stable resistance behavior under mechanical stress, whereas their capacitive responses differed according to the integration strategy. The pocket structure demonstrated lower signal drift and higher repeatability, whereas the tunnel design offered higher sensitivity at the cost of increased variability. Notably, both architectures retained sensing functionality after sterilization and chemical exposure. These results emphasize that textile architecture is a key factor in determining sensor reliability, with the pocket‐type design providing a robust platform for capacitive sensing in functional engineering textiles.
The vast compositional space of Al–Co–Cr–Fe–Ni–Ti‐based high‐entropy alloys made it difficult to establish a one‐to‐one correspondence between alloy composition and mechanical properties using traditional trial‐and‐error methods. In the present study, a machine learning framework integrating feature engineering and data augmentation techniques has been established to thoroughly reveal the compositional dependence of room‐temperature tensile elongation in the Al–Co–Cr–Fe–Ni–Ti alloy system. By introducing empirical parameters and phase composition features and employing Pearson correlation analysis and feature selection along with exhaustive computation, the optimal feature subset comprising Al, Ti, VEC, δ r , and Δ H was determined. Moreover, the SMOTER algorithm was applied to balance the data distribution in order to address the sparsity of high‐elongation data, achieving a relatively high model coefficient of determination ( R 2 ≈ 90). Combined with SHAP and feature importance analyses, valence electron concentration (VEC) and atomic radius difference (δr) emerged as dominant factors in determining plasticity. The composition‐dependent machine learning model for tensile elongation proposed in this study demonstrated high prediction accuracy, reaching over 90%.
This study demonstrates binder‐free laser powder bed fusion (PBF‐LB) of 8 mol% yttria‐stabilized zirconia (8YSZ) using a femtosecond laser and a triangular scan strategy that controls heat accumulation by varying scan‐vector length. Laser power (31–52 W), scan speed (100–500 mm s −1 ), defocus (+2 to +14 mm), and pulse repetition rate (0.5–32 MHz) were screened. Surface homogeneity was evaluated by a Canny‐based Surface Pixel Score, grain‐size distributions were quantified from SEM micrographs using kernel‐density statistics from more than 4,000 grains, and thermal behavior was analyzed by infrared thermography supported by finite‐difference simulations. The optimum parameter set (52 W, 400 mm s −1 , +12 mm defocus, 2 MHz) produced the largest continuous vitrified region. Thermography revealed thermal regimes and abrupt temperature jumps near scan‐vector lengths of 7 and 17 mm, indicating changes in heat accumulation consistent with high‐temperature densification and localized melting. Simulations reproduced the position and qualitative form of these signatures. Rectangular scans confirmed scan‐speed‐dependent grain refinement, reducing mean grain size from 51.8 µm at 200 mm s −1 to 40.3 µm at 500 mm s −1 . The results establish an additive‐free route toward vitrified, fine‐grained 8YSZ layers.
Reliable joining of nickel‐based superalloys, composites, or other dissimilar materials combinations remains a persistent challenge in aerospace and nuclear energy applications, where brittle intermetallic compound (IMC) formation, residual interfacial defects, and insufficient service performance restrict the practical deployment. This review systematically examines high‐entropy alloy (HEA) interlayers as a promising solution to these challenges. From a compositional perspective, this review discusses the evolution from single‐phase solid‐solution HEAs to dual‐phase, eutectic, and refractory systems. It highlights how their sluggish diffusion kinetics and high phase stability suppress undesired IMC formation and promote sound metallurgical bonding. In terms of structural design, the transition from single‐layer to double‐layer and sandwich/composite configurations is discussed, demonstrating how these architectures accommodate thermomechanical mismatch and reduce interfacial defects. However, achieving superior joint performance under extreme service conditions requires a synergistic compositional and structural design strategy. Building on these design principles, the novel multiinterlayer composite bonding (MICB) strategy employing a BNi‐2/HEA/BNi‐2 sandwich interlayer is innovatively developed. Incorporating a core of L1 2 ‐strengthened HEAs or chemically complex intermetallic alloys (CCIMAs), this approach effectively addresses the long‐standing strength–ductility trade‐off in superalloy joints. Finally, future challenges are also outlined, including the artificial intelligence (AI)‐assisted compositional design, high‐precision manufacturing methods, and comprehensive performance evaluations.
To systematically investigate the influence of thermal history on microstructure evolution along the deposition direction in Ti–7Mo–4Al–3Nb–2Cr–2Zr alloy during laser melting deposition, the morphological changes in the α phase have been mainly researched. Results indicate that the region from the substrate up to 20 mm in height consists of columnar grains, with the equivalent circle diameter decreasing from 344 to 308 μm. Between 20 and 40 mm, equiaxed grains are observed, with diameters decreasing from 260 to 246 μm. Concurrently, the α‐phase morphology evolves from basket‐weave to a bimodal structure, consisting of forked primary α p and dispersed secondary α s , and finally to acicular α. The grain boundary α phase transitions from a continuous to a discontinuous state, eventually forming a continuous thin film.The observed microstructural evolution is attributed to the shift in heat dissipation behavior with increasing height: from a predominantly unidirectional thermal gradient to multidirectional heat flow, which induces the columnar‐to‐equiaxed transition of β grains. Meanwhile, the decreased cooling rate promotes an increase in the initial size of the α phase, whereas the subsequent reduction in thermal cycling suppresses its coarsening. The ultimate tensile strength increases from 1038.0 MPa in region D to 1182.3 MPa in region B and subsequently decreases slightly to 1169.6 MPa in region A. Meanwhile, fracture toughness increases from 62.3 MPam 1/2 in region D to 71.5 MPa m 1/2 in region B, followed by a decrease to 59.0 MPa m 1/2 in region A. The mid‐upper region (B) exhibits an optimal strength‐toughness combination, mainly due to the refined α phase within the bimodal structure: lamellar α hinders dislocation motion, promoting accumulation at α/β interfaces and enhancing strength; meanwhile, nanoscale α accommodates localized plastic deformation during fracture, delaying crack initiation and improving toughness.
A novel Al 1.5 Ti 6.5 Zr 2 Nb 3 Ta 2 Mo 0.5 Cr 0.5 multiprincipal element alloy (MPEA) with a coherent BCC/B2 microstructure containing cuboidal BCC precipitates was designed. The microstructural evolution and corresponding mechanical properties under different heat‐treatment conditions were systematically investigated. After aging at 873 K, a coherent BCC/B2 microstructure is formed, exhibiting an excellent combination of high yield strength (~1200 MPa) and good compressive plasticity (~50%). This good mechanical performance is attributed to the cooperative deformation of kink bands and the BCC/B2 microstructure, where dislocation shearing of ordered B2 phase and the associated structure formation provide effective strengthening while maintaining plastic deformability. With increasing aging temperature to 973–1073 K, the B2 phase becomes thermodynamically unstable, leading to the precipitation of hexagonal Al 3 Zr 5 phases and subsequently (Al, Cr) 2 Zr Laves phases, accompanied by a degradation in both strength and ductility. High‐temperature compression tests reveal that the 873 K‐aged alloy retains a relatively high strength (~912 MPa) at 873 K, whereas a pronounced softening occurs at higher temperatures due to the transformation into a single BCC solid solution driven by enhanced elemental solubility. This work highlights the critical role of coherent BCC/B2 microstructures in governing both strengthening and deformation mechanisms in MPEAs.
This study investigates the effect of laser in situ heat treatment on the grain boundary characteristics and microstructure of GH4169 superalloy fabricated via point‐type forging–laser deposition. By controlling the laser remelting rate (4 and 6 mm/s), systematic EBSD analysis was conducted to evaluate grain boundary distribution, misorientation angles, crystallographic texture, and kernel average misorientation. The results demonstrate that at a remelting speed of 4 mm/s, the fraction of high‐angle grain boundaries reaches 87.0%, the average grain size is refined to 11.2 μm, and the material achieves optimal mechanical properties with tensile strength of ~700 MPa and internal hardness of 450–520 HV. This work provides a theoretical basis for optimizing laser additive manufacturing processes through in situ heat treatment.
A mechanically reconfigurable flexible frequency selective surface (FSS) with dual‐band and polarization selectivity is proposed based on buckling‐guided 3D assembly strategy. The structure consists of periodically arranged symmetric double split‐ring resonators (SRRs) in a bilayer configuration. By releasing the prestrain in a stretched substrate, a deterministic 3D architecture is formed, enabling continuous and reversible structural reconfiguration under biaxial tensile strain. The deformation modulates the coupling between incident electromagnetic waves and the resonant units, resulting in polarization‐selective transmission. For transverse magnetic wave, the structure exhibits a distinct dual‐stopband response, with resonant frequencies shifting toward lower frequencies as the tensile strain increases, while high transmission is maintained for transverse electric waves across the measured frequency range. The mechanical and electromagnetic models are employed to analyze the response mechanism, and the effects of the SRR radius and gap width on resonance tuning are discussed. The proposed structure features simple fabrication, stable performance under large deformation, and precise tunability, offering promising applications in flexible tunable filters and polarization‐selective electromagnetic devices.
A mechanically actuated sonic crystal is designed, fabricated, and experimentally validated as a modular element for assembling a symmetry‐guided multifunctional acoustic platform. By selecting a specific underlying symmetry, we demonstrate that the number and type of achievable device functionalities can be rigorously determined within a unified group‐theoretical framework. In this work, we realize three out of the four predicted classes of devices—acoustic switch, controlled confined propagation, and beam splitter—by mechanically rotating unit cells composed of cylinders with embedded anisotropic C‐shaped inclusions (CSIs). Numerical simulations and experiments confirm the corresponding wave‐manipulation behaviors, while also validating the predictive power of the symmetry‐based classification. Finally, we provide a clear design route for implementing the remaining class, namely acoustic logic‐gate operations, completing the full set of functionalities supported by the chosen symmetry.
This study formulates an organic vehicle system using triethylene glycol monobutyl ether as the solvent, ethyl cellulose as the binder, and oleic acid as the dispersant to investigate the low‐temperature pressureless sintering of silver paste. The effects of sintering temperature and the composite ratios of silver powders with different sizes and morphologies (400 nm spherical silver powder, 2 μm flake silver powder, and 300 nm flake silver powder) on the electrical and mechanical properties of the sintered bodies were systematically studied. Results indicate that increasing the sintering temperature reduced the number of pores while increasing their size, leading to improved densification that approached the compact structure of bulk silver, thereby optimizing performance. The morphology and size of the silver powders significantly influenced the sintering behavior. Flake powders reduced interfacial resistance through two‐dimensional planar contacts, whereas spherical powders enhanced electrical performance and shear strength by forming more sintering necks. A synergistic effect was achieved by combining spherical and flake powders. Notably, when spherical silver powder was blended with 300 nm flake silver powder at a ratio of 1:3, a minimum porosity of 1.658% was achieved, along with a shear strength of 63.34 MPa and a volume resistivity of 4.85 × 10 −6 Ω cm. Furthermore, comparative analysis revealed the distinct advantages of the smaller flake powder over its larger counterpart (2 μm) in enhancing sintered quality, providing experimental basis for the material selection of silver paste.
This work revisits and integrates results on the fatigue behavior of advanced bainitic steels (in particular, nanostructured bainitic steels), with special emphasis on the role of the microstructure and the specimen geometry. These studies encompass the determination of intrinsic fatigue limits from notched specimens; crack growth rate measurements; fatigue crack initiation and propagation tracking in specimens containing artificial defects manufactured by focused ion beam; and microstructural examination. The novelty of the present work lies in an integral discussion that accounts for volume effects as a function of the specimen geometry and microstructural aspects. Different characteristic microstructural length scales controlling fatigue behavior have been evaluated in scenarios with variable notch (and defect) sharpness and size. The results reveal a complex, double‐fold influence of retained austenite and the fact that crack nucleation is governed by resolved shear stresses on coplanar crystal slip systems of bainitic ferrite and austenite.
Calcium oxide is a promising high‐temperature CO 2 sorbent for calcium looping, yet its practical application is limited by rapid capacity decay due to sintering and pore collapse during cyclic carbonation/calcination. Although metal doping has been widely employed to improve structural stability, the quantitative relationship between dopant‐induced phase evolution, reaction kinetics, and long‐term durability remains unclear. Here, seven metal dopants (Zr, Mn, Ce, Ni, Fe, Cr, and Co) were incorporated into CaO to systematically evaluate their influence on multiscale reaction behavior. Among them, Zr‐modified CaO exhibits superior cyclic stability, retaining more than twice the CO 2 uptake of pristine CaO after 40 cycles. Structural analyses (XRD, BET, SEM) reveal that Zr promotes the formation of a thermally stable CaZrO 3 phase that acts as a refractory skeletal/spacer phase to mitigate morphological densification and preserve pore connectivity. Isoconversional and pressure‐corrected kinetic analyses show that Zr stabilizes the apparent activation energy across the full conversion range and maintains a consistent phase‐boundary‐controlled mechanism, thereby delaying diffusion limitations during cycling. In contrast, other dopants either reduce initial activation energy without preventing long‐term degradation or introduce unfavorable kinetic effects. These results establish a quantitative structure–energy–stability correlation for designing durable CaO‐based CO 2 sorbents.
In this study, a lead‐free ternary poly(vinylidene fluoride) (PVDF)/strontium titanate (SrTiO 3 )/poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) nanocomposite was developed to enhance piezoelectric and piezo‐photocatalytic performance. SrTiO 3 nanoparticles (NPs) were synthesized via an autocombustion route and incorporated with PEDOT:PSS into the PVDF matrix, utilizing the solution‐casting method. Structural and spectroscopic analyses confirmed the successful formation of cubic‐phase SrTiO 3 NPs and their uniform incorporation within the polymer matrix. The incorporation of SrTiO 3 NPs and PEDOT:PSS significantly promoted electroactive phase formation in PVDF, yielding an electroactive phase content of 97.74% for the optimized composite. Complex impedance spectroscopy revealed enhanced interfacial polarization and improved dielectric behavior. Consequently, the optimized nanocomposite exhibited a high dielectric constant ε ′ ≈ 101.26 at 40 Hz frequency. The corresponding piezoelectric nanogenerator delivered an open‐circuit voltage of 45.50 ± 0.58 V and a maximum power density of 51.76 ± 1.33 μW cm −2 under periodic mechanical excitation. Furthermore, the optimized composite demonstrated enhanced piezo‐photocatalytic degradation of methylene blue dye, attributed to efficient charge separation induced by the piezoelectric potential under simultaneous mechanical and light stimulation.
Colossal permittivity (CP) materials have attracted significant attention due to their crucial role in advancing electronic device miniaturization and performance enhancement. Herein, we present a novel CP material (Ba 0.99 La 0.01 Zr x Ti 1− x O 3 (BLZT)), which exhibits high CP performance in optimal composition ( x = 0.075) that with a colossal dielectric permittivity of 4.1 × 10 5 and a low loss tangent of 0.057 at 1 kHz, as well as X9F‐type temperature stability [( ε′‐ε′ 25 °C )/ ε′ 25 °C ≤ 7.5% in a range −55–200 °C]. A systematic investigation of the mechanism of CP was conducted using XPS and complex impedance spectroscopy, demonstrating that the outstanding CP performance originates from multiscale polarization mechanisms induced by A/B‐site synergistic doping. Electron‐pinned defect dipoles (EPDD) associated with La 3+ donor doping dominate high‐frequency localized polarization. Grain refinement and grain‐boundary engineering enhance the internal barrier layer capacitance (IBLC) effect, improving intermediate‐ to low‐frequency interfacial polarization. This work demonstrates an effective strategy that, through A/B‐site synergistic defect engineering, achieves X9F colossal dielectric BaTiO 3 ‐based ceramics.
Plate warping and insufficient interfacial bonding strength easily occur when Mg/Al composite plates are prepared by traditional synchronous rolling processes. A novel asymmetric snake rolling process is proposed in this article. AZ31B magnesium alloy and 5052 aluminum alloy were used for this study. The effects of snake rolling on the macroscopic morphology, microstructure evolution, and mechanical properties were investigated by comparing the deformation behaviors between snake rolling and synchronous rolling under different thickness ratios, combined with the finite element method (FEM) and microstructure characterization. The results indicate that the additional shear strain introduced by the staggered rolls in snake rolling, can effectively suppress the warping tendency of the composite plates and significantly improve the plate flatness. At the microscopic level, the shearing action significantly refines the matrix grains, reducing the grain size on the Mg side to 2.1–2.4 μm, and promotes the fragmentation of interfacial metal oxide films and atomic diffusion. The tensile strength of the snake‐rolled samples reaches 250 MPa, the elongation reaches a high level of 25%–27%, and the interfacial tensile‐shear strength reaches to a maximum of 72 MPa, respectively. This study provides important theoretical support and a technical pathway for fabricating high‐performance Mg/Al composite plates via snake rolling.
The synthesis of alumina monoliths is carried out by intrusion of an alumina precursor paste into the channels of a 3D‐printed template, followed by drying and calcination of the composite. To obtain durable monoliths, several approaches are applied: (a) conducting an additional phase transition to increase crystallite mobility; (b) slowing the composite drying rate by increasing the amount of slow‐boiling plasticizers in the paste and introducing isothermal exposure at low temperatures; and (c) introducing alumina additives with different porosity to reduce composite shrinkage. The first approach yields a strong alumina monolith with a monomodal pore size distribution. The other approaches produce coherent monoliths with multimodal pore size distribution, suitable for comparative catalytic tests in the hydroconversion of vacuum oil residue ( T = 400 °C, p(H 2 ) = 10 MPa, LHSV = 0.62 h −1 , H 2 /Feed = 1000 L/L). The monolithic catalyst demonstrates greater activity as a guard catalyst than the reference pellets, as evidenced by a 9% reduction in product density and a 79‐fold reduction in kinematic viscosity (vs. 4% and 3‐fold for pellets, respectively). This difference is attributed to more efficient external mass transfer in the structured macrocapillary geometry.
MXenes, a rapidly growing family of two‐dimensional transition‐metal carbides, nitrides, and carbonitrides have attracted significant attention because of their layered structures, metallic conductivity, and tunable surface chemistry. These unique characteristics allow precise control of their physical, and chemical properties, making them promising materials for diverse advanced applications. This review provides an overview of recent progress in MXene research, covering their structure, synthesis, properties, and applications. The structural characteristics of MXenes, including atomic arrangements, surface terminations, and interlayer interactions, are discussed to explain their influence on electrical, thermal, optical, and electrochemical behavior. Recent advances in synthesis methods are then examined, including conventional top‐down etching techniques and emerging fluoride‐free, hydrothermal, and scalable approaches that aim to improve safety, reproducibility, and industrial applicability. The review further highlights important structure–property relationships, emphasizing the roles of compositional tuning, surface functionalization, and hybridization in controlling charge transport, ion diffusion, mechanical flexibility, and stability. Finally, recent MXene applications in energy storage, smart textiles, healthcare, environmental remediation, and electromagnetic interference shielding are reviewed, together with the growing role of artificial intelligence in materials design and performance optimization.
Magnesium‐based alloys are promising solid‐state hydrogen storage materials, but their practical applications remain limited by sluggish kinetics and high operating temperatures. This study investigates the combined effects of low‐content vanadium (V) and carbon black (CB) on commercial AZ31 alloy prepared via high‐energy ball milling. The low V content of 0.5 wt.% provides catalytic activity while minimizing gravimetric capacity loss, whereas CB assists powder refinement and suppresses particle agglomeration when combined with V. The AZ31 + 3CB control sample achieves 6.09 wt.% at 375 °C, confirming the individual contribution of CB. Among the investigated compositions, AZ31 + 0.5V + 3CB exhibits the highest absorption capacity of 6.46 wt.% at 375 °C, compared with 5.11 wt.% for pristine AZ31. Kissinger analysis shows that the apparent activation energy decreases from 144.990 kJ mol −1 for AZ31 to 104.372 kJ mol −1 for AZ31 + 0.5V + 3CB, while the time required to reach 90% capacity shortens from 1956 to 1062s. Furthermore, the composition maintained good cyclic stability, with 94.2% capacity retention after 50 cycles. These results demonstrate that the optimized V/CB comodified AZ31 system enhances hydrogen storage kinetics through CB‐assisted microstructural refinement and V‐assisted catalytic activation.
Metals and alloys exhibit scale‐dependent mechanical behavior governed by crystallographic slip, requiring explicit consideration of slip systems in microscale simulations of polycrystals. Crystal plasticity (CP) theory addresses this by explicitly modeling anisotropy and slip‐system interactions. In this study, the texture evolution of an aluminum wire under shear was investigated using the spectral solver of the crystal plasticity fast Fourier transform (CPFFT) method on a 100‐grain representative volume element (RVE). An initial non‐random ⟨100⟩ fiber texture was assigned based on electron backscatter diffraction (EBSD) measurements, and the accuracy of the CPFFT predictions was validated against experimental EBSD results. Pole figure and ODF analyses of the deformed sample confirmed the partial development of FCC simple‐shear‐related texture components, indicating a shear‐induced modification of the inherited wire‐drawing texture rather than a complete replacement by a fully developed shear texture. EBSD misorientation analysis showed an increase in the high‐angle grain‐boundary fraction from 28.52% to 46.05% and an increase in the average misorientation angle from 11.86° to 20.39° after half‐turn torsion, indicating enhanced torsion‐induced misorientation development. Both experimental and simulated inverse pole figures exhibited an intensified [001] || SD fiber after shear. Furthermore, the sensitivity of the simulations to grain number and grid resolution was examined as a numerical verification step. Increasing the number of grains from 10 to 100 and 500 improved predictive accuracy, while variations in grid resolution had minor effects. The yield strength increased from 80 to 92.3 MPa, and the average hardness increased from 53.06 to 57.46 HV after deformation.
