The Al/steel bimetallic structure shows great potential in fabricating lightweight structures and transition joints. In this study, a coated flux is utilized to achieve steady processibility of Al/steel bimetallic structures by cold metal transfer wire-arc additive manufacturing. The effect of coated flux layer on macro morphology, formability enhancement, interfacial microstructure, mechanical property and fracture morphology of Al/steel bimetallic structures are analyzed. The result reveals that the introduction of flux layer can effectively dissolve and react dense oxide films on surfaces of high-temperature Al alloy molten pool, to promote reaction wetting between the dissimilar metals. Meanwhile, the flux can stabilize droplet transfer process and avoid random movement of cathode spots to guarantee good arc stiffness, therefore significantly achieving formability enhancement of Al/ steel bimetallic structures. The interfacial reaction layer is identified as Fe-Al based reaction layer, the sufficient flux layer effectively promotes IMCs growth and will strengthen interfacial metallurgical bonding of Al/steel interface. The Al/steel bimetallic structures display excellent shear strength of not less than 70 MPa and tensile strength of 103.3 MPa, while the more deposition times will not affect shear strength of the bimetallic structure but resulting in slight tensile strength decline.

The additive manufacturing of titanium/aluminum dissimilar metals can achieve the integration of lightweight and high strength. However, joining these two metals poses significant challenges. In this study, 6061 aluminum alloy was used as the substrate, and TC4 welding wire was employed as the cladding material for the laser additive manufacturing of titanium-aluminum dissimilar metals. With the aim of controlling the interfacial fusion ratio and minimizing intermetallic compound formation to enhance the interface performance, the process parameters were optimized. The optimal parameters were determined through single-factor experiments and nonlinear regression analysis. Under these parameters, the interfacial tensile strength of the aluminum/titanium dissimilar metal structure reaches to 60.67 MPa. The microstructural evolution of the dissimilar metal interface under different additive manufacturing layer numbers was analyzed. The results show that as the number of titanium alloy additive manufacturing layers increases, the brittle acicular compounds at the titanium-aluminum interface gradually diffuse, transform into granular particles and eventually aggregate into a continuous layer. The evolution of interfacial residual stress was analyzed through finite element simulation. The results indicate that the interfacial residual stress initially increases, then decreases, and finally rises sharply, with severe stress concentration observed at both ends of the weld bead.

An extended state-variable yield criterion for Ti4522XD powder is established through hierarchical multiscale information transfer from mesoscale multi-particle finite element method (MPFEM). This framework facilitates predictive sensitivity analysis of hot isostatic pressing (HIP), capturing the effects of capsule geometry, process parameters, and loading strategies on densification kinetics and density uniformity. The model incorporated density- and temperature-dependent elastic modulus E(rho(v), T) and a percolation-based plastic Poisson's ratio nu(p)(rho(0), rho(v), T, ) accounting for initial relative density (IRD, rho(0)). The extended state-variable yield criterion was developed in a differentiable PyTorch framework, capturing density strengthening, hybrid Ludwik-Voce work hardening, Johnson-Cook-type strain-rate sensitivity, and softening from recovery and dynamic recrystallization (DRX). In addition, a cascading style sheet (CSS)-enhanced MATLAB Web App enabled interactive visualization of yield surface evolution. The UVSCPL subroutine reliably reproduces relative density (RD, rho(v)), equivalent plastic strain (EPL), hydrostatic pressure (P-hyd), and plastic volumetric strain increment (Delta epsilon p vol), validating subroutine correctness for HIP simulations. Parametric HIP analyses quantified the effects of capsule geometry, process parameters, and loading strategies. Specifically, a 2 mm-thick filleted capsule reduced the maximum-minimum RD difference (RDmax-min) by 50% relative to a fillet-free design. Concurrently increasing the peak temperature (1160 degrees C -> 1300 degrees C) and peak pressure (90 MPa -> 180 MPa) elevated the maximum RD (RDmax) from 0.953 to 0.988, while extending the holding time from 1 h to 4 h decreased the low-density fraction with RD < 0.95 (V-low), improving local densification. Asynchronous and stepwise loading strategies optimized early compaction and mid-to-late-stage pore closure, with principal component analysis (PCA) confirming that stepwise loading achieves the highest densification and spatial uniformity. This multiscale constitutive modeling provides a robust approach for predictive HIP simulations and process optimization of Ti4522XD powder, offering a generalizable strategy applicable to other powder systems.

Wear prediction in revolute clearance joints becomes particularly challenging when the contacting profiles evolve continuously during operation. The difficulty lies not only in evaluating local pressure and wear depth, but also in maintaining consistency among contact analysis, pressure evaluation, profile updating, and profile reconstruction. To address this issue, this paper proposes a unified computational framework for dynamic wear prediction in clearance joints with evolving irregular profiles. The framework combines point-level contact analysis based on a robust interpolated collinearity formulation, local pressure evaluation using a modified Winkler-type model, and wear updating and profile reconstruction based on Archard’s law.A planar slider-crank mechanism with a revolute clearance joint is used for numerical investigation. Results under bushing-only wear show that profile updating changes wear prediction from an open-loop accumulation process to a closed-loop wear-geometry evolution process. Within the same closed-loop route, pressure-distribution models mainly affect local smoothness and boundary continuity, while the updating direction governs the internal consistency between contact analysis and profile evolution. Under double-sided wear, the proposed framework yields more plausible wear sharing and profile evolution than representative assembled routes.

This study proposed a low-temperature method for the rapid preparation of high-performance CNTs reinforced Cu matrix composites by ultrasonic additive manufacturing. The tensile strength of the composites had reached to 258 MPa, while the elongation was 48.76 %. The thermal conductivity of the composites was 412.96 W/m & sdot;K.

High-strength low-alloy (HSLA) steel typically fails during service because of high-temperature wear. The tribological performance of HSLA steel prepared by powder metallurgy or vacuum arc melting was studied at 20 degrees C and 200 degrees C, and the microstructural evolution and wear mechanism were elucidated. The results revealed that as the temperature increased from 20 degrees C to 200 degrees C, the average friction coefficient and wear rate of the two types of samples decreased. Compared with the vacuum arc melting samples, the powder metallurgy samples have excellent frictional properties, with a wear rate of 1.31 x 10(-7) g/(N center dot m) at 200 degrees C, corresponding to only 47.12% of that of the vacuum arc melting samples. The adhesion layer composed of Fe2O3 and Fe3O4 has excellent lubrication effects. The formation of high-density dislocations, high surface hardness, and significant refinement of the surface microstructure improve the ability to resist plastic deformation, thereby preventing the formation of large-scale cracks that cause extensive peeling.

To solve the problems of low efficiency and imbalanced duplex phase proportion of weld seam caused by complex thermal cycles in traditional arc welding of duplex stainless steel, a novel high-efficiency magnetically controlled laser-MIG hybrid welding technology for 2507 super duplex stainless steel was proposed. Xiris camera and high-speed imaging system were used to systematically study the plasma morphology and droplet transfer mode under different excitation parameters to elucidate the action mechanism of external excitation magnetic field in laser-MIG hybrid welding process. The results indicate that the addition of an external magnetic field changes the force state of plasma and droplet, thereby changing the plasma morphology and droplet transfer mode. Within a certain range, the applied external magnetic field can effectively regulate the plasma morphology, accelerate the droplet transfer frequency, simultaneously improve the droplet transfer stability, and improve the weld formation quality. When the excitation current is 1.0 A, and the excitation frequency is 75 Hz, the plasma presents a stably burning “bell shape”; the droplet transfer mode is stable jet transfer, and the weld formation quality is optimal.

Magnetically controlled plasma-flux cored arc welding (Plasma-FCAW), as an efficient hybrid arc welding method, is characterized by excellent deep penetration and low spatter. However, the welding process is susceptible to disturbances due to the complex underwater environment. To address this issue, a self-developed electromagnetic excitation device was used in this study to apply a transverse magnetic field to the underwater hybrid Plasma-FCAW process. This magnetic control facilitated flexible coupling between the two arcs, thereby effectively improving the stability of the hybrid welding process and the weld bead formation. On this basis, welding process experiments were carried out in water environment with different salinities and temperatures. The influence of the water condition on droplet transfer behavior, weld formation, as well as microstructure and properties was studied. The results show that increased salinity shortens the droplet transfer cycle, raises the cooling rate, and reduces the weld width. Water temperature significantly affects arc stability and droplet transfer behavior: the droplet transfer cycle shortens at low temperature, while it becomes irregular at high temperature. Both increased salinity and decreased water temperature increase the content of side-plate ferrite and acicular ferrite in the weld zone. In contrast, higher water temperature increases the pearlite content in the heat-affected zone, thereby affecting the hardness of weld.

Monitoring spoilage-related gases is important for the quality evaluation and safety assurance of fresh food. Ammonia (NH3), a representative volatile marker released during food deterioration, can be generated not only during ambient storage and retail display but also under refrigerated transportation and distribution. However, developing chemiresistive NH3 sensors that operate without external heating while maintaining effective sensing performance across these conditions remains challenging. Herein, vacancy-engineered SbSI nanorods were developed as NH3 sensing materials. The vacancy-rich SSI-TAA sensor delivered a response of 172% toward 10 ppm NH3 at room temperature, which was approximately 4.9 times higher than that of vacancy-free SbSI. Moreover, the response increased to 368% at 5 degrees C, indicating effective sensing performance at low temperature. Theoretical calculations reveal that sulfur vacancies enhance NH3 adsorption on SbSI in the room-temperature paraelectric state, with stronger NH3 adsorption in the low-temperature ferroelectric state, supporting the experimentally observed sensing enhancement under ambient and refrigerated conditions. This work demonstrates that vacancy engineering is an effective strategy for improving NH3 sensing in SbSI and highlights the potential of SbSI-based sensors for freshness evaluation and spoilage monitoring of fresh food.

The growing demand for heterogeneous metal structures in aerospace and new energy vehicle industries has made the reliability of welding or additive manufacturing for such structures a critical industry focus. This paper proposes a hybrid solid-liquid phase additive manufacturing technique. The specific implementation involves first consolidating a niobium interlayer onto a aluminum alloy substrate via ultrasonic solid-phase additive manufacturing, followed by sequentially depositing titanium alloy structures using laser wire-feed additive manufacturing to achieve high-quality, rapid fabrication of Ti/Al dissimilar structures. During this hybrid manufacturing process, the ultrasonic technique induces strong mechanical interlocking through plastic deformation and atomic diffusion, while the subsequent laser deposition optimizes metallurgical bonding and suppresses brittle intermetallic formation via precise thermal control. The resulting dissimilar metal interface exhibits a unique hybrid microstructure combining solid-phase bonding and solidified liquid-phase reaction zones, significantly enhancing tensile and shear strength of the heterogeneous metal structures while effectively reducing residual stresses. Compared to direct additive manufacturing, the maximum tensile strength of the single-track ten-layer additive sample had reached to 127MPa, an increase of 72%; then the maximum interfacial shear strength was increased of 244.7% to be 81MPa when multi-track and multi-layer additive manufacturing was carried out, strengthened by interlocking chains between adjacent tracks on the interface. This solid-liquid phase hybrid additive manufacturing technology also provides an innovative solution for other cost-effective and high-performance dissimilar metal components.

Developing vibration-damping materials capable of withstanding the rigorous thermal and mechanical environments of space remains a significant challenge. In this work, 60 vol% TiNi particle-reinforced aluminum matrix composites (TiNip/Al) were fabricated via pressure infiltration. The interfacial microstructure and resultant properties were tailored by pre-oxidizing TiNi particles at temperatures of 300, 500, 600, and 700 degrees C. Results indicate that the pre-oxidation layer effectively inhibited brittle interfacial reactions between the TiNi reinforcement and the Al matrix, leading to a substantial increase in bending strength, reaching 400 MPa. Furthermore, the controlled interface introduced interfacial slip, thereby enhancing damping capacity. The resulting composites demonstrated a synergistic combination of high strength and superior damping across a wide temperature range (-80 degrees C to 180 degrees C), maintaining a loss tangent (tan delta) consistently above 0.017, with a peak value of 0.0675 at the phase transition temperature. The underlying damping mechanism was elucidated using an interfacial slip theoretical model.

Grains refinement induced by ultrasound was regarded as a main mechanism for improving strength. This study exhibits that other strengthening effects resulting from ultrasound when low power is applied, in the absence of average grain size reduction, have been substantially underestimated. Ultrasound achieves strengthening via micro/nano-scale precipitates, increasing dislocation density, and inhibited intermetallic compounds, notably, the average grain size in the weld shows no decrease, which has rarely been reported. Compared to the condition without ultrasound, an ultimate tensile strength improvement of ∼50% was achieved at a 4 μm ultrasonic amplitude, despite being accompanied by a ∼ 33% increase in the average grain size. It reached ∼131% of the base metal's strength. We also characterized the atomic-scale strain near the Al/nano-scale Si interface and analyzed interface configuration in combination with the results of density functional theory (DFT) calculations. These findings offer an alternative strategy for Si modification and provide a new perspective on strengthening via ultrasound.

This study proposes a cellulose-biomimetic structural strategy and employs a composite process of directional freezing and salt precipitation to successfully fabricate a hydrogen-bond-enhanced anisotropic Poly(vinyl alcohol)(5)-chitosan hydrogel(1) (P-5-CS1). This hydrogel exhibits a tensile strength of 8.6 MPa (approximate to 33-fold higher than that of P-5-CS1-FT prepared via the freeze-thaw method) and a toughness of 29.1 +/- 1.4 MJ/m(3) (approximate to 80-fold higher than that of the P-5-CS1-FT). This hydrogel simultaneously achieves strain (713%), water content (77%), and porosity (82%). While its water content matches that of human tissues, its tensile properties outperform typical PVA-based wound dressings and even surpass those of natural tissues (e.g., muscle and cartilage). To adapt to diverse chronic wound scenarios, phosphorylated chitosan (PCS) is incorporated to form P-5-CS1-P. In vitro and in vivo experiments confirm that P-5-CS1-P exhibits robust bioactivity, maintaining > 100% L929 viability, reducing IL-1 and IL-6, and accelerating SD rat full-thickness wound closure to 95%. The design integrates physical protection, directional fluid management, and drug delivery, while PCS loading adds anti-inflammatory, antibacterial, and pro-healing functions, offering a promising synergistic strategy for chronic wound care.

A cyclic quenching (CQ) heat treatment process was used to improve the balance between the strength and toughness of high-strength low-alloy (HSLA) steel via grain refinement and precipitation strengthening effects. The embrittlement problem of HSLA steel (impact energy of only 65.8 J) was effectively addressed with the CQ process. After four CQ cycles, the impact energy reached 95.1 J, the tensile strength reached 1568.4 MPa, and the elongation increased to 12.84%. The improvement in the mechanical properties was attributed to the refinement of the martensitic structure and the uniform precipitation of carbides. The fine grain strengthening and precipitation strengthening mechanisms are the main reasons for the increase in yield strength. The excellent impact toughness is attributed to the high density of high-angle grain boundaries (HAGBs), which consume considerable crack extension energy, whereas the fine carbides promote the homogenization of dislocation slips and reduce local stress concentrations.

In order to improve welding efficiency and achieve flexible manufacturing of the divertor components for tokamak devices, laser welding-brazing was employed to join W and oxide dispersion strengthened (ODS) steel. Due to the significant differences in the physical properties between W and ODS steel as well as the formation of brittle intermetallic compounds (IMCs) at the interface, achieving a reliable joint presents substantial challenges. High-entropy alloys (HEAs) exhibit high-entropy and sluggish diffusion effects. To mitigate elemental reaction and diffusion at the W/ODS steel interface, a 0.8 mm thick CoCrFeNiCu HEA interlayer was introduced to assist the welding process. Then, process parameter optimization was conducted to obtain a high-performance W/ CoCrFeNiCu/ODS steel joint. The final results demonstrated that, after process optimization, the reaction layer thickness at the interface was reduced from 6.9 mu m to 1.4 mu m with the addition of the CoCrFeNiCu HEA interlayer, and the interfacial microstructure transformed from Fe2W-IMCs to a Fe-based solid solution. The fracture mode of the joint evolved from a single brittle fracture mechanism to the coexistence of two distinct modes: ductile-brittle mixed fracture and brittle fracture. The optimized weld joint achieved an average tensile strength of 212 MPa, representing a 41% increase compared to the direct laser welding-brazed W/ODS steel dissimilar joint without an interlayer.

In this study, three types of microalloyed martensitic steels with different Nb and Ti contents were prepared using powder metallurgy techniques, and comprehensive comparative analyses of their microstructures and mechanical properties were conducted. The results show that Nb and Ti can effectively refine the sizes of prior austenite grains (PAGs) and martensitic laths, promote the formation of (Ti, Nb, V)C precipitates, and increase the strength of steel via precipitation strengthening. However, excessive Ti content can lead to the coarsening of (Ti, Nb, V)C particles, thereby deteriorating the plasticity and toughness of the 8Nb12Ti sample. During the austenitization process, (Ti, Nb, V)C carbides with TiC particles as the core preferentially precipitate. During the tempering stage, M3C, M7C3, and VC carbides sequentially precipitate, reducing the carbon content in the matrix and helping to suppress crack initiation. The 8Nb6Ti sample exhibits excellent tensile properties and impact toughness due to the high proportion of high-angle grain boundaries and the refined microstructure. In contrast, the 8Nb12Ti sample exhibits a relatively low level of impact work at room temperature, which stems from its internal coarse (Ti, Nb, V)C particles. Moreover, the quasi-cleavage fracture dominated by particles accelerates the fracture process, which decreases the impact toughness.

Selective laser melting (SLM) is considered an effective technology in fabricating high-performance metalbonded diamond tools with integrated internal cooling and chip evacuation channels. However, the formation of certain defects during the SLM process significantly compromises the mechanical properties and service life of diamond tools. Defect generation exhibits a strong correlation with laser processing parameters, among which laser hatch spacing constitutes a critical factor governing successful laser spot overlapping between adjacent molten tracks. To investigate the defect formation mechanisms, this work establishes a double-track multi-scale phase transition-multiphysics coupled model for diamond/CuSn20 composites. Through integrated CFD-based numerical simulation and experimental approaches, the effects of hatch spacings variations on molten pool evolution, defect generation mechanisms, and mechanical properties of diamond-metal composites were investigated. The principal findings are as follows: (1) Residual temperature from the first molten track modifies the initial temperature of the second molten track. Simultaneously, the temperature gradient generated by the second laser pass induces remelting of the overlapping. (2) At reduced hatch spacing, thermal damage preferentially occurs in diamond grits, whereas enlarged hatch spacings promote pore formation, unmelted zones, and interfacial gaps in overlapping regions. (3) Specimens fabricated at an 80 mu m hatch spacing exhibit the highest compressive strength. Although their COF initially exceeds that of 100 mu m-spaced specimens, it decreases below the latter's COF after 14 min of testing. This work provides a systematic analysis of diamond migration behavior and molten pool defect genesis during melting-solidification processes.

Al-6wt%Si semi-solid alloy billets were prepared via the liquid phase reaction sintering process by using elemental Al and Si powders as starting materials. Cup-shaped components were fabricated by direct semi-solid thixoforming at 685-595. with the liquid phase fraction in the range of 0.141-0.196. By microstructure observation and mechanical testing, the influence of the liquid phase sintering and subsequent thixoforming conditions on the microstructure evolution and mechanical properties of the final components was investigated. The results show that, when the liquid phase fraction of the alloy billet is in the range of 0.141-0.167, cup-shaped components with uniform microstructure and no forming defects can be obtained by direct thixoforming. Due to the strengthening effect of the fine Al grains and the Si particles and precipitates, the component thixoformed by using billet with a liquid phase fraction of 0.167 presented the best mechanical properties, with yield strength, ultimate tensile strength and elongation achieving 115MPa, 220MPa and 38%, respectively. It is evident that the semi-solid thixoforming process proposed in the present study turns out to be a practical way to fabricate high-performance Al-Si alloy components.

A titanium aluminum alloy (Ti-45Al-2Mn-2Nb-1B, at%) was prepared using hot isostatic pressing (HIP). Thermal simulation compression were carried out at an elevated temperature of 1100-1250 degrees C, strain rate between 0.001 and 1 s-1, and a reduction in height of 50%. The thermal deformation behaviors, microstructural evolution, and dynamic recrystallization (DRX) mechanisms were investigated. The results show that stress- induced phase transformation from gamma (L10) to alpha 2 (hcp) is facilitated through the successive glide of a/6 [11-2] Shockley partial dislocations across alternating {111} planes of gamma phase. The DRX were analyzed using Geometrically necessary dislocations (GND). In the alpha + gamma phase region, the DRX becomes more abundant at an increase in temperature to 1250 degrees C and a decrease in strain rate to 0.001 s- 1. The misorientation analysis showed that continuous dynamic recrystallization (CDRX), which occurs through subgrain rotation and misorientation accumulation, weakens at elevated temperatures and low strain rates. However, discontinuous dynamic recrystallization (DDRX), characterized by the dominance of strain-induced boundary migration mechanism (SIBM) and bulging nucleation, develops more extensively under the same parameters. The microstructure after thermal deformation contains true twins (TT) and pseudo twins (PT) and the DRX grains near twin boundaries (TBs) show a peak misorientation angle of 89 +/- 3 degrees, driven by high strain energy at twin intersections. Among the various DRX mechanisms, DDRX emerges as the dominant. This comprehensive analysis offers novel insights into DRX mechanisms, providing valuable guidance for optimizing the hot working process of Ti-45Al-2Mn-2Nb-1B (at%) alloy.

There is a problem of real-time detection difficulty in road surface damage detection. This paper proposes an improved lightweight model based on you only look once version 5 (YOLOv5). Firstly, this paper fully utilized the convolutional neural network (CNN) + ghosting bottleneck (G_bneck) architecture to reduce redundant feature maps. Afterwards, we upgraded the original upsampling algorithm to content-aware reassembly of features (CARAFE) and increased the receptive field. Finally, we replaced the spatial pyramid pooling fast (SPPF) module with the basic receptive field block (BasicRFB) pooling module and added dilated convolution. After comparative experiments, we can see that the number of parameters and model size of the improved algorithm in this paper have been reduced by nearly half compared to the YOLOv5s. The frame rate per second (FPS) has been increased by 3.25 times. The mean average precision (mAP@0.5: 0.95) has increased by 8