Advanced Engineering Materials最新文献

In order to further improve the comprehensive mechanical properties of as-rolled SiC/7075Al composites, the microstructure and mechanical properties of the composites are modified by pulse current-assisted treatment (PCAT). The results show that the pulse current acts on the interior of the material in a unique way, reducing the nucleation barrier of the precipitated phase. Two nano-scale precipitated phases of MgZn₂ (η′) and Mg₂Si (β′) are formed inside the composite. The fine precipitates play a significant role in the strengthening of dislocation and dispersion of the material, which makes the material obtain excellent strength and plasticity. The mechanical properties analysis reveals that the yield strength (YS), ultimate tensile strength (UTS), and elongation of the samples subjected to PCAT are 223.6, 434.5 MPa, and 20.6%, respectively. Compared to the as-rolled samples, the YS exhibits an enhancement of 4.7%, the UTS increases significantly by 25.6%, and the elongation improves remarkably by 108%. PCAT enhances the strength and plasticity of SiC/7075Al composites, breaking the competition between strength and plasticity.

The use of responsive pillar arrays and cilia-like structures is linked with many groundbreaking applications, including microfluidic devices, biomedical applications, and soft robotics. To be effective, cilia or pillar arrays must exhibit flexible and controllable motion tailored to their specific applications. In this context, in this work, developing a compliant structure, which combines longitudinal stiffness controlled by a shape-memory alloy and magnetically actuated pillars, is aimed at. Polydimethylsiloxane is used as the matrix material, while nickel–titanium (NiTi) alloy provides stiffening to the base, and the pillars are enriched with iron via magnetron sputtering. The structures are generated through cast molding, employing pillar array-forming templates obtained by additive manufacturing. Various physicochemical and mechanical analyses are conducted to assess the composite's properties, including tensile testing, pullout test, and magnetometry. Overall, tailored dexterity and actuation are achieved by controlling temperature and magnetic field application. This advancement not only demonstrates the feasibility of creating responsive pillars at a relatively low cost—in comparison to commercial iron nanoparticles—and environmentally friendly techniques but also opens avenues for their integration into sophisticated devices requiring precise and adaptable movements. Future research should focus on optimizing the actuation efficiency and exploring broader applications in bioengineering and robotics.

In this study, the possibility of employing ZrN/AlSi10Mg composite powders with 10, 20, and 30 wt% ZrN and a low-pressure cold spraying (CS) unit to enhance the surface properties of AlSi10Mg obtained through laser powder bed fusion (LPBF) is investigated for the first time. A high-energy ball mill is used to produce composite powders from AlSi10Mg and ZrN powders. ZrN/AlSi10Mg powders are sprayed onto the surface of LPBFed AlSi10Mg at a pressure of 0.7 MPa and a temperature of 400 °C. It is demonstrated that the utilization of composite powders facilitates a uniform distribution of ceramic particles in the coating and reduces the share of their losses during the CS process to 2%. It is found that the microhardness and elastic modulus of composite coatings increase with increasing mass fractions of ZrN, while the wear rate (WR) decreases. A change in the wear mechanism from adhesive to abrasive is observed. It is possible to increase the microhardness and elastic modulus of the LPBFed AlSi10Mg surface with a coating containing 30 wt% ZrN by 43% (193 ± 5 HV_0.1) and 62% (105 ± 9 GPa), respectively, and reduce the WR by 25% (8.26 ± 0.09) × 10⁻⁴ mm³ m⁻¹.

A composite structure (L-LDMPP) consisting of localized aluminum foam, a localized microperforated plate (MPP), and a double-layer MPP is proposed to enhance sound absorption. A simulation model using COMSOL is developed to predict the sound absorption coefficient and investigate the acoustic benefits of localized aluminum foam and localized MPP. A comparative analysis is performed to evaluate the sound absorption performance of four configurations: L-SMPP (localized aluminum foam with a single-layer MPP), L-DMPP (localized aluminum foam with a double-layer MPP), L-LSMPP (localized aluminum foam with a localized MPP and a single-layer MPP), and L-LDMPP (localized aluminum foam with a localized MPP and a double-layer MPP). The model's accuracy is validated against experimental data. Results show that localized aluminum foam, localized MPP, and double-layer MPP optimize acoustic impedance matching. The sound absorption characteristics of L-LDMPP are divided into two domains: the resonance acoustic domain, influenced by the double-layer MPP structure behind the localized aluminum foam, and the coupled acoustic domain, influenced by both the localized aluminum foam and localized MPP.

Ruthenium (Ru) has been identified as a durable and relevant substitute to copper (Cu) to answer the access resistance lowering of the back-end-of-line (BEOL) metal levels, which is a high-priority concern for future devices. Herein, the nonequilibrium and local properties of pulsed scanning laser annealing (SLA) technique are used to enhance the structural and electrical properties of thin polycrystalline Ru layers (<30 nm). For the best annealing conditions, transmission electron microscopy observations show a substantial grain size enlargement, with large grains (≈80 nm) occupying the whole layer height. It goes with a 53% resistivity reduction, measured by 4-point probe, confirming the strong grain boundary scattering reduction. A Mayadas–Shatzkes model incorporating temperature-dependent resistivity measurements allows the extraction of promising reflectivity and specularity coefficients of around 0.58 and 0.98, respectively. Beyond the best conditions, failure modes for devices integration are observed, such as surface wrinkling and local buckling. Given the studied system, a semiquantitative analysis of these phenomena is given and simulations based on the finite element method are used to find further optimal annealing conditions. This study confirms the potential of Ru as a promising BEOL material, but also SLA as a convincing technique for future 3D architectures.

Re-Entrant Honeycomb Metamaterials

The cover image illustrates a re-entrant honeycomb metamaterial with graded shape morphing, fabricated via additive manufacturing. The shape morphing is achieved by adaptively changing the geometric parameters of sigmoid-based morphing functions to enable linear auxetic behaviors. Six cell designs with different morphing parameters, highlighted in the cover image, are analyzed to achieve linear auxetics with minimal deviations in the negative Poisson’s ratio. The experimental results reveal a 70% reduction in the relative variation of Poisson’s ratio, while maintaining a high magnitude. Further details can be found in article 2400889 by Keun Park and co-workers.

Conductive Yarns

In article number 2401629, Qiaolan Fan, Yangxin Zhou, and co-workers fabricate conductive graphene-PET (polyethylene terephthalate) composite yarns through the integration of synergistic multi-wall carbon nanotube (MWCNT) additives, utilizing industrially established melt-spinning process. These yarns are endowed with conductivity, facilitated by conductive pathways established through interfacial contacts between graphene and MWCNTs.

Meta-Absorbers

In article number 2401738, Tong Cai, Chunsheng Guan, Wenye Ji, and co-workers propose a multiplexing integration meta-absorber in a one-layer planar board by harnessing the coupling of four resonant modes, achieving an ultra-thin thickness and an ultrawide absorption band. Our work presents a feasible absorption strategy that is closer to practical applications and may pave a way for the development of ultra-thin meta-devices.

Pore emergence during the laser powder bed fusion (LPBF) technique significantly impairs mechanical characteristics. Therefore, the elimination of pores is a pressing issue to ensure the quality and productivity of manufactured components. The objective of this study is to evaluate how certain parameters, such as laser power, layer thickness, exposure time, hatch distance, and volumetric energy density, affect the microstructure and tensile properties of AlSi10Mg specimens generated by LPBF in both their original state and after undergoing a solution heat treatment. The volumetric energy density (VED) is often used to optimize process parameters in the LPBF approach since it thoroughly evaluates all four main factors. This article specifically examines the impact of VED on the microstructural features and tensile characteristics of printed parts. The high VED of 78.13 J mm⁻³ decreases the occurrence of porosity and defects, hence enhancing the tensile characteristics of the specimens produced. Regarding specimens that have undergone solution heat treatment, the recommendation is to decrease the laser power to 350 W, which results in a VED of 60.76 J mm⁻³ and outstanding tensile characteristics. These findings provide fresh perspectives to achieve improved tensile properties of AlSi10Mg parts using LPBF processing settings.

The joint microenvironment contributes significantly to arthritis by shaping the synovial sheath and inducing cartilage damage. Hydrogen has antioxidant and anti-inflammatory potential and shows promise in the treatment of arthritis, particularly in selectively reducing free radical levels while preserving normal cell redox reactions. However, the short retention time of hydrogen and its low solubility in body fluids pose challenges for its use to achieve an optimal therapeutic effect. Smart biomaterials respond to alterations in physiological parameters and external stimuli, enabling precise targeting and continuous local treatment, thus maintaining local H₂ concentration at the treatment site. In this review, the recent advances in hydrogen-producing nanomaterials for the treatment of arthritis are presented and the challenges and prospects for their clinical application are evaluated.