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This study explores the mechanical properties of graphene/aluminum (Gr/Al) nanocomposites through nanoindentation testing performed via molecular dynamics simulations in a large-scale atomic/molecular massively parallel simulator (LAMMPS). The simulation model was initially subjected to energy minimization at 300 K, followed by relaxation for 50 ps under the NPT ensemble, wherein the number of atoms (N), simulation temperature (T), and pressure (P) were conserved. After the model was fully relaxed, loading and unloading simulations were performed. This study focused on the effects of the Gr arrangement with a brick-and-mortar structure and incorporation of high-entropy alloy (HEA) coatings on mechanical properties. The findings revealed that Gr sheets (GSs) significantly impeded dislocation propagation, preventing the dislocation network from penetrating the Gr layer within the plastic zone. However, interactions between dislocations and GSs in the Gr/Al nanocomposites resulted in reduced hardness compared with that of pure aluminum. After modifying the arrangement of GSs and introducing HEA (FeNiCrCoAl) coatings, the elastic modulus and hardness of the Gr/Al nanocomposites were 83 and 9.5 GPa, respectively, representing increases of 21.5% and 17.3% compared with those of pure aluminum. This study demonstrates that vertically oriented GSs in combination with HEA coatings at a mass fraction of 3.4% significantly enhance the mechanical properties of the Gr/Al nanocomposites. [ABSTRACT FROM AUTHOR]

In this study, Al6061 alloy matrix composites reinforced Al2O3-decorated reduced graphene oxide (Al2O3/RGO) with 0.1, 0.3 and 0.5 weight present (wt%) were successfully fabricated using high energy ball milling and hot extrusion techniques. The microstructures of these Al2O3/RGO/Al6061 aluminum matrix composites (Al MMCs) were characterized. The results showed that Al2O3/RGO were uniformly distributed within the Al6061 matrix and tightly bonded to the matrix. Al2O3 encapsulation on RGO surface would prevent the formation of Al4C3 brittle phase in matrix, ensuring that there was no reaction between the reinforcement and the matrix Al6061. Tensile strength and Vickers hardness tests demonstrated that the mechanical properties of Al MMCs significantly increased with addition of Al2O3/RGOs. Remarkably, Al MMCs with 0.1 wt% reinforcement showed tensile yield and tensile strengths of 270 MPa and 286 MPa, respectively, which were 49% and 43% higher than those of pure Al6061 prepared using the same process. Furthermore, the 0.1 wt% Al2O3/RGO composite also showed the best plastic deformation capability in considering of the strength. [ABSTRACT FROM AUTHOR]

With the booming of telecommunication and microelectronics, it is essential to develop electromagnetic interference (EMI) shielding materials with low reflectivity characteristics to avoid the secondary pollution from electromagnetic waves (EMWs). Herein, we fabricated a series of hierarchical polypyrrole/carbon nanofiber (PPy/CF) composites with multilayer PPy films. The EMI shielding performance can be adjusted by attaching different layered PPy films. The EMI shielding efficiency (SE) of PPy/CF composite films can reach to 74.59 dB with an electrical conductivity of 3.02 × 10–3 S/mm. Moreover, in order to make the composite film have excellent strength and flexibility, we specially designed an acetone-soluble polyimide (PI) resin to encapsulate PPy/CF. After packaging with PI, the composite films are imparted with high flexibility and mechanical properties with the tensile strength and modulus of 4.65 and 153.03 MPa, respectively. Moreover, the resultant PI/PPy/CF composite films also possess favorable Joule heating performance and sensing monitoring. The Joule heating temperature of PI/PPy/CF films reaches 131.0 °C within 15 s when the applied voltage is 5 V. The fabricated composite films are promising for applications in the fields of aerospace, telecommunication, and microelectronic engineering and multifunctional wearable devices. [ABSTRACT FROM AUTHOR]

The booming development of communication technology and electronic equipment has put forward higher requirements of flexibility, electromagnetic interference (EMI) shielding performances, and service reliability for the EMI shielding materials. Herein, the flexible polyurethane@Ti3C2Tx/silver nanowires (PU@Ti3C2Tx/AgNWs) composite films with cocontinuous segregated structures are developed by a facile layer‐by‐layer hydrogen bonding assembly followed by hot‐pressing approach using PU sponge as the 3D skeleton template. Benefiting from the cocontinuous segregated structures, the flexible composite films exhibit high electrical and mechanical properties, excellent EMI shielding, and Joule heating performances. The EMI SE of the composite films can reach as high as 88 dB in X‐band (8.2–12.4 GHz). At a supplied voltage of 4.0 V, the composite films exhibit a high steady‐state Joule heating temperature up to 116.7 °C. The flexible cocontinuous segregated composite films with high working stability show great application potentials in EMI shielding and Joule heating systems in aerospace, weapon equipment, and wearable devices. [ABSTRACT FROM AUTHOR]