Advanced Engineering Materials最新文献

In recent years continued advancements in high-precision fabrication technologies have led to new possibilities for tuning the tribological properties of materials through surface patterns. Applied to frictional metamaterials, this opens opportunities to enhance energy dissipation performance through the design of the contact surface topography. This study investigates the influence of various metamaterial contact surface patterns, which we refer to as frictional metasurfaces, on energy dissipation in sliding friction through both experiments and FE simulations. Several surface pattern geometries were tested and compared to the baseline represented by a flat smooth surface. The length scale of these patterns was constrained by manufacturing considerations. In addition, the use of different materials for the metasurface and the main body of the metamaterial was examined. These tests and simulations show that non-smooth surfaces can indeed increase friction and energy dissipation, but the magnitude of their contribution emerges from interactions between the geometry and the elasticity of the metamaterial structure that supports the contact surface, as manifested through the contact pressure distribution, and particularly the scale of pressure and friction concentrations and their evolution during the load cycle.

To address the issues of poor corrosion resistance and poor biocompatibility faced by magnesium alloys in bone implants, ceramic layers doped with different concentrations of strontium are developed on AZ91D magnesium alloy substrates using a one-step microarc oxidation technique. Subsequently, the composition and morphology of the coating are analyzed using scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Corrosion resistance is evaluated in simulated body fluid via electrochemical testing. The antibacterial properties and biocompatibility of the coating are characterized through antibacterial experiments, hemolysis experiments, and cell proliferation experiments. The results show that the coating possesses a rough porous structure, mainly composed of MgO, Mg₂SiO₄, and Mg phases. Electrochemical test results show that the corrosion resistance of the prepared strontium-containing coating is 1–2 orders of magnitude higher than that of conventional coatings. Antibacterial experiments show that strontium-containing coatings have good antibacterial properties. Finally, in cell proliferation experiments, strontium-containing coatings exhibit superior biocompatibility compared to magnesium substrates and conventional microarc oxidation coatings, the cell proliferation rate remains at 154.86% after 120 h of culture.

As the mobility sector advances toward battery-powered transportation, the demand for lightweight structural components with high mechanical integrity continues to grow. Metal–polymer hybrid structures offer a promising solution; however, direct joining between dissimilar materials often results in weak interfacial anchoring, necessitating additional fasteners or adhesives. This study presents a robot-assisted laser texturing technique for fabricating high-aspect-ratio, surface-tilted, recast-based microstructures that enhance the strength of metal–polymer joints. A six-axis robotic system enables precise control of the laser incidence angle, interline pitch, and scanning path, promoting recast layer overlap while minimizing thermal distortion through an anomalous scanning strategy. The method supports scalable fabrication of various microstructural patterns, including groove, circular, and wobble geometries. Tensile tests demonstrate strength improvements of up to 13.41× for groove structures and 14.11× for wobble structures, the latter providing direction-independent interlocking. These results highlight the potential of this approach for robust, adhesive-free integration of metal–polymer hybrids in lightweight mobility applications.

Fused filament fabrication offers the ability to 3D print complex geometries made from plastic filament materials; however, these parts are mechanically outperformed by parts created by traditional fabrication methods. To overcome this challenge, a high-performance polymer poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) is incorporated as an additive into two common engineering thermoplastics, poly(acrylonitrile-styrene-acrylate) (ASA) and poly(acrylonitrile-butadiene-styrene) (ABS). Structures printed from these polymer blends are more mechanically robust compared to those prepared from the parent polymers, with low loading levels (1–5 wt%) of PPO improving the elastic strength by up to ≈30% relative to the parent terpolymers. Even at higher loading levels (10  and 20 wt% PPO), there is no evidence of additive aggregation in the model thin films, which is supported by compositional analysis of the copolymers and chemical analysis via time-of-flight secondary ion mass spectrometry. The enhancements in mechanical properties of ASA and ABS blends appear to be a consequence of homogeneous incorporation of the PPO additive. This work explores expanding materials-property space using miscible blends of engineering thermoplastics to improve mechanical performance as a general approach to overcoming challenges with parts created by melt-based material extrusion printing.

Aluminum alloys 2024 and 5083 are critical for lightweight engineering, yet their reliable dissimilar joining remains challenging. This study employs friction stir welding (FSW) to fabricate 2024/5083 joints, integrating multicharacterization (optical microscopy, scanning electron microscopy, electron backscatter diffraction (EBSD)) and thermal simulation to elucidate heat input's: 600–1200 rpm; 20–80 mm min⁻¹ regulation on microstructures and properties. Novelty lies in identifying 600 rpm (20–40 mm min⁻¹) as the optimal parameters: the nugget zone (NZ) undergoes full continuous dynamic recrystallization, forming fine equiaxed grains (≈6.06 μm) with high-angle grain boundaries (>65%) and uniform dispersion of Al-Cu/Mg phases. This yields an ultimate tensile strength (UTS) of 295.61 MPa (surpassing both base metals) and 12.85% elongation. In contrast, 800 rpm induces excessive heat, triggering static recrystallization grain growth, bimodal NZ microstructures, Mg segregation, and defects—drastically reducing UTS to <180 MPa and elongation to <0.5%. EBSD verifies optimal parameters suppress texture anisotropy, while thermal simulation underpins the “heat input–recrystallization–performance” correlation. This work establishes a multiscale “defect-microstructure-property” chain, advancing FSW parameter optimization for dissimilar Al alloys by clarifying 600 rpm as the critical threshold for balancing thermomechanical effects.

The well-defined porosity architectures and distinct charge characteristics of ionic covalent organic polymers (ICOPs) have garnered significant attention as promising candidates for drug delivery, adsorption, separation, and gas collection and storage applications. This study reports the synthesis of two novel ICOPs, TPE-COP and PY-COP, based on tetraphenylethene and pyrene cores, respectively, with viologen serving as the conjugated bridge. To complement the experimental findings and provide microscopic insights into the adsorption mechanism, density functional theory calculations are performed. Results indicate that the PY-COP model exhibits a more planar structure compared to TPE-COP, explaining the observed morphological variations: spherical for TPE-COP and stacked morphology for PY-COP. TPE-COP exhibits markedly stronger stabilization toward oxoanions. Saturated adsorption capacities are determined for both ICOPs against selected anionic pollutants, demonstrating competitive performance compared to existing adsorbents. For KMnO₄, TPE-COP and PY-COP demonstrate capacities of 0.77 and 0.35 g MnO₄⁻ g⁻¹, respectively. Similarly, for Na₂Cr₂O₇, the saturated adsorption capacities are 0.17 g Cr₂O₇²⁻ g⁻¹ for TPE-COP and 0.06 g Cr₂O₇²⁻ g⁻¹ for PY-COP. These results demonstrate the superior adsorption performance of TPE-COP compared to PY-COP, highlighting the influence of structural design on adsorption efficacy.

A liquid–solid compound casting method is used for fabricate TC4/20 steel bimetallic composites. Systematic investigations are conducted on the interfacial evolution mechanisms and mechanical behavior under varying pouring temperatures (1490, 1520, and 1550 °C). Microstructural characterization reveals interdiffusion of Fe, C, and Ti elements across the interface, forming an intermediate transition layer containing FeC, FeTi, Fe₂Ti, and TiC intermetallic compounds. The interfacial microhardness exhibits temperature-dependent characteristics: peak values reach 1085.6 HV (1490 °C) and 1024.5 HV (1520 °C), while a remarkable enhancement to 1494.8 HV is achieved at 1550 °C due to intensified compound formation. Shear strength demonstrates a nonmonotonic relationship with temperature, attaining an optimal value of 143.6 MPa at 1520 °C, 9.6%, and 57.2% higher than those at 1490 and 1550 °C, respectively. These findings establish that precise control of pouring temperature within 1490–1520 °C enables effective regulation of elemental diffusion kinetics and interfacial reaction products, ultimately governing the mechanical performance hierarchy of the bimetallic system.

The effect of stress relieving and substrate preheating on the grain refinement of additively manufactured Ti-6Al-4V at room and elevated temperatures is investigated. Specimens are produced using wire-based directed energy deposition under vacuum conditions. The microstructure is characterized by scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and X-ray diffraction (XRD). Tensile tests are conducted at room temperature and at 700 °C. The as-deposited specimens exhibit a heterogeneous microstructure consisting of fine acicular α′-martensite and fine Widmanstätten structures. Substrate preheating at 600 °C enables a complete transition from a columnar grain structure in the as-deposited condition to a refined prior-β grain structure. The as-substrate-heated specimens show the highest tensile strength of 1010 MPa with 3% elongation at room temperature and 600 MPa with 15% elongation at 700 °C.

This study examines the interactions between strontium (Sr), antimony (Sb), and bismuth (Bi) in recycled ADC12 alloys and their impact on eutectic Silicon and solidification kinetics. Microstructural and thermal analyses show that specific Sb and Bi additions neutralise Sr's modifying effect, converting eutectic silicon from a modified to an unmodified morphology. This transition is marked by a shift in eutectic Si growth temperature from 564 °C (fibrous) to ≈571–572.6 °C (flake-like). A critical Sr/(Sb + Bi) ratio was identified: ratios below approximately 0.38 result in an unmodified structure, while ratios above around 0.42 lead to modification. Electron backscatter diffraction and transmission electron microscopy demonstrate that modified Si exhibits an independent eutectic Al orientation, distinct from primary Al, with a higher twinning density. The interaction mechanism involves the preferential pre-eutectic formation of a quaternary Mg₂(Sb, Bi)₂Sr intermetallic phase, which consumes free Sr. As a result, further alloying beyond saturation mainly increases this intermetallic phase without additional Si refinement. Excessive Sr additions, intended to counteract this neutralisation, can lead to harmful Sr-rich phases, such as Al₂S_i2Sr. These findings highlight the importance of carefully controlling tramp elements in recycled Al–Si alloys to ensure consistent microstructure and predictable mechanical properties.

In this article, a diode-pumped solid-state laser marking system (maximum average power, 25 W; wavelength, 1064 nm) is used to texture Ti6Al4V substrates. This investigation examines the effect of varying marking speed (50 and 150 mm s⁻¹) and average power (21.25 and 23.75 W), corresponding to linear energy densities ranging from 0.142 to 0.475 J mm⁻¹. Surface characterization is performed using a 3D focus variation microscope, atomic force microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and contact angle measurements. Surface roughness variations from 0.71 to 1.004 μm are shown after applying linear energy densities of 0.425 and 0.475 J mm⁻¹, respectively. A microstructural study demonstrates a reordering of the α and β titanium phases. The applied energy significantly influences surface morphology and chemical composition, increasing the oxygen content and indicating surface oxidation. Under this study's processing and measurement conditions (sessile drop with artificial saliva), all textured samples exhibit increased contact angles (from 95 ± 5° for the substrate to 116.03 ± 6.32° and 118.9 ± 6.8° for the textured samples), indicating a shift toward more hydrophobic behavior. The combined effects of increased micro-roughness and oxide formation explain this trend.