Advanced Engineering Materials最新文献

Template-assisted confinement has emerged as a versatile strategy for controlling the structure and function of liquid crystal elastomers (LCEs). By guiding mesogen alignment and polymer network formation within predefined geometries, these approaches enable LCEs with programmable actuation, optical properties, and mechanical responses. This review provides a comprehensive overview of templating methods for LCE fabrication, including planar substrates, porous scaffolds, droplet-based confinement, colloidal assemblies, microstructured molds, fibrous templates, and direct ink writing. For each category, how the geometry, surface properties, and processing conditions influence alignment quality and material performance is highlighted. The unique capabilities and challenges associated with each method are also discussed. Finally, emerging directions such as hierarchical and reconfigurable templates, multifunctional composites, and applications in soft robotics, adaptive optics, and biomimetic systems are outlined. Overall, these insights highlight the growing potential of confinement-guided approaches in advancing the next generation of responsive LCE materials.

The oscillating laser welding of 2 mm-thick WE43 rare-earth magnesium alloy is carried out with different modes. The oscillating laser modes mainly include nonoscillating, square, circular, figure-of-eight, and spiral oscillation. The effects of oscillating laser welding mode on the macroscopic morphology, microstructure, molten pool flow, and mechanical properties of WE43 welded joints are investigated. The macroforming and microstructure of welded joints with the spiral oscillation mode are the best. The spiral oscillation laser welding can achieve the conditions of heat conduction welding mode and turbulent flow of molten pool, and effectively inhibits the formation of keyholes and the appearance of biting defects. Because of its fine and uniform microstructure, the tensile strength of the welded joint reaches 230.3 MPa, which is 92.1% of the tensile strength of the base material. The research has enriched the theory of rare-earth magnesium alloy oscillation welding to a certain extent and provides the theoretical data of rare-earth magnesium alloy WE43 oscillation laser welding.

It is investigated how the addition of Cu influences the pitting corrosion behavior of carbon steel induced by (Ca, Mn)S-(Al, Mg)O complex inclusions. While the overall microstructure of the steel matrix remained unchanged, Cu markedly altered the morphology and elemental distribution of these inclusions. First-principles calculations revealed that Cu preferentially adsorbed on the CaS interface due to its lower adsorption energy and stronger Cu-S orbital hybridization. This preferential adsorption facilitated the phase separation of MnS and CaS and resulted in localized Cu enrichment within CaS regions. At higher Cu contents, a dense and continuous Cu-rich layer developed around the inclusions. This layer served as a physical barrier, effectively impeding the ingress of corrosive species, retarding the dissolution of sulfide inclusions, and suppressing pit propagation. Immersion tests demonstrated that increasing Cu content resulted in smaller and shallower pits and reduced localized corrosion rates. Electrochemical analyzes further validated the enhanced corrosion resistance at higher Cu content. The synergistic action of interfacial adsorption and barrier-layer formation accounts for the reduced pitting susceptibility of Cu-alloyed carbon steel.

To tackle dye-related water pollution, developing cost-effective adsorbents with high efficiency in removing residual dyes from wastewater is of vital importance. Herein, magnetic composite hydrogels designed for dye adsorption and recyclability is synthesized by combining polyvinyl alcohol (PVA), xanthan gum (XG), and iron (II, III) oxide (Fe₃O₄) magnetic nanoparticles. The PVA/XG hydrogel matrix is fabricated via freeze–thaw technique, and the Fe₃O₄ nanoparticles are generated in situ within the hydrogel network. The structural and functional characteristics of the PVA/XG/Fe₃O₄ magnetic hydrogels are systematically investigated using swelling behavior, turbulence stability, thermogravimetric analysis, and scanning electron microscopy. The impacts of adsorbent dosage, initial concentration, and solution pH on adsorption properties are comprehensively evaluated. Furthermore, the adsorption mechanisms of congo red (CR) and methylene blue (MB) onto the hydrogel are elucidated via kinetics studies, isotherm modeling, thermodynamic analyses, and Fourier transform infrared characterization. The Langmuir adsorption isotherm models predicted maximum adsorption capacities of 364.70 and 409.19 mg g⁻¹ for MB and CR, respectively. A novel PVA/XG/Fe₃O₄ magnetic hydrogel is developed that addresses a critical challenge in water treatment: the cumbersome recovery of adsorbents. By integrating rapid magnetic separability with high adsorption capacity, this material provides an innovative and sustainable solution for environmental remediation.

Continuous SiC fiber-reinforced titanium matrix (SiC_f/Ti) composites are considered promising candidates for low-pressure compressor blades of aero engines. However, overload failure under coupling conditions of elevated temperature and bending load is the typical failure mode of blade materials, which is important to understand bending damage evolution at service temperature. Herein, three-point bending interrupted tests of SiC_f/Ti composite panel are conducted on parallel specimens at 723 K to capture different damage stages. Combining scanning electron microscopy and micro-computed tomography, together with finite element analysis, is employed to investigate the failure mechanisms. The composite exhibits a bending strength of 1689 MPa at 723 K. The damage evolution follows a sequential process, interfacial debonding (stage I), tensile-side fiber fracture (stage II), matrix cracking and multiple fiber breaks (stage III), cladding fracture and limited compressive-side fiber failure (stage IV), and final catastrophic fracture (stage V). Distinct stress states lead to different fracture morphologies on the tensile and compressive sides, with tensile stress identifies as the primary factor governing failure. These findings establish a coherent understanding of the correlation between stress states and bending damage evolution, providing valuable insights for the structural designs and service reliability of SiC_f/Ti composite components in high-temperature applications.

While the deformation mechanisms of fine-grained magnesium alloys have been extensively documented, the hot deformation behavior and underlying microstructural evolution of ultra-coarse-grained cast magnesium alloys, commonly found in industrial-scale castings, remain largely unexplored and poorly understood. To address this gap, plane strain compression tests are conducted to simulate the rolling process of a coarse-grained AM60B magnesium alloy (≈378.3 μm) at 250–310 °C with strain rates ranging from 0.5 to 12.75 s⁻¹. The stress–strain curves reveal a pronounced decrease in stress at 250 °C/0.5 s⁻¹, indicating an unusual softening phenomenon. The microstructural evolution of coarse-grained alloy is systematically investigated. Results reveal that extensive lamellar twinning occurs in strain-localized regions, leading to twin-induced dynamic recrystallization (TDRX) at lower temperatures (250 °C). Subsequently, continuous dynamic recrystallization (CDRX) mediates the bridging of TDRX lamellae, while discontinuous dynamic recrystallization (DDRX) contributes to their broadening, with twin extension being DDRX-driven. This elucidated TDRX-dominated synergistic mechanism is established as the fundamental cause of both the abnormal flow softening and the enhanced microstructural refinement observed during deformation at 250 °C and 0.5 s⁻¹ in coarse-grained AM60B magnesium alloy. At higher temperatures of 280 °C and 310 °C, DDRX and CDRX become the dominant mechanisms, superseding TDRX.

Adv. Eng. Mater., 2023, 25(2), 2200945

https://doi.org/10.1002/adem.202200945

The units for the Reduced Modulus and Hardness on Figures 8 and 9, respectively, were erroneously listed as MPa rather than GPa. This error does not affect the body of the text or the conclusions. In section 3.3. Mechanical Properties, values were discussed in relation to each other (e.g., “The hybrid samples achieved an average reduced modulus of more than 337 times larger and an average hardness of more than 172 times larger than the respective averages of the monomitic dehydrated samples.”), which remains true for the values with the correct units. Additional discussion is found in section 3.4. Liquid Absorption Properties, comparing the absorption and mechanical properties of sol-gel materials to those fabricated in this study. In this section, it is stated, “While some of these sol-gel materials may be able to absorb more fluid, they have less mechanical resistance than what was achieved in this study.” Because the error used MPa rather than GPa, this discussion point is still true and not affected by the error.

We apologize for this error.

Direct 3D printing of green bodies and indirect 3D printing for assisting a casting process represent two promising applications of additive manufacturing (AM) based on digital light processing (DLP) for creating high-precision metallic components. Since direct 3D printing is still limited to specific materials, like copper and stainless steel, there is a need to expand this technology to other alloys. The ability to scale it up is further hampered by issues in preprocessing, printing, and post-treatment. This review discusses the complete process chain and applications of DLP in detail. Subsequently, some challenges, such as scattering and residual char, are identified as the remaining obstacles in the current DLP technology. To increase DLP's applicability to high-value industries, a summary of solutions, like preparation of refractive index-tuned slurries, a method to assist in finding printing parameters, and using nanosize powders in mixed slurries, is elucidated. Details of the future research directions pertaining to the method for utilizing carbon-free photopolymer binder, multistage debinding-sintering cycles, and incorporating machine-learning-assisted real-time monitoring to achieve defect-free, industrial-scale production are mentioned. This work provides a template to fully realize DLP-AM's potential as a flexible, effective platform for advanced casting workflows and various metallic material fabrication.

Honeycomb sandwich structure with tunable electromagnetic parameters serves as an important load-bearing, stealth-shielding integrated component in the domain of aviation equipment. To cope with the long-range detection of radar detection technology, honeycomb sandwich structure with wide operating bandwidth and excellent wave-absorbing efficiency has ongoingly sparked large global attention. Damage degradation behavior of wave-absorbing efficiency is also a critical indicator parameter, but rarely conduct in-depth discussions. In this work, a honeycomb sandwich structure with multiple discrete resonant absorption peaks is proposed and the reflection loss is less than −10 dB in 4–18 GHz frequency band. Enhanced wave-absorbing efficiency is observed for penetrating damage mode with increasing incidence angle in 0°–60° compared with no damage mode. The corresponding damage degradation mechanism is revealed by decoupling surface reflection, bottom reflection of electromagnetic wave, ratio of inherent absorption and interference cancellation. This work provides valuable insights for the assessment of wave-absorbing efficiency degradation behavior of honeycomb sandwich structure.

This study investigates the effect of Mo addition on the phase composition, microstructure, wear resistance, and corrosion behavior of remelted Fe_0.5CoCrNi_1.5Nb_0.68Mo_x (x = 0.0, 0.1, 0.3, 0.5) high-entropy alloy (HEA) coatings. The coatings are fabricated through laser cladding followed by laser remelting to enhance their properties. Results indicate that the remelted HEA coatings comprise a face-centered-cubic (FCC) matrix, Laves phase, and NbC, where the FCC phase dominates the structure, the Laves phase serves as the main strengthening constituent, and NbC is sparsely distributed. Increasing Mo content promotes the formation of the Laves phase, resulting in microstructural evolution from columnar to refined dendritic structures, along with an interdendritic network. The Laves phase effectively impedes further dendritic growth and suppresses the FCC phase, leading to grain refinement and improved phase distribution. Notably, the Fe_0.5CoCrNi_1.5Nb_0.68Mo_0.5 coating exhibits enhanced microhardness and wear resistance due to the increased Laves phase. Additionally, Mo dissolution in the FCC phase improves corrosion resistance by reducing pitting susceptibility. This study elucidates the relationship between Mo addition, Laves phase formation, and microstructural evolution, providing a theoretical basis and experimental reference for optimizing the performance of HEA coatings.