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Crystallographic and structural anisotropies are essential in governing the direction of crack propagation, particularly for brittle materials and their composites. However, capturing their combined effects and relative influence on crack-path formation at atomistic-continuum scales remains challenging. This paper presents a multiscale framework to determine the role of crystallographic anisotropy in controlling fracture in 3C-SiC and its composites. This framework decomposes the continuum media into a collection of "crystal-symmetry preserved sub-domains" (CSPS) before finite element discretization. Interactions and continuum scale behavior of the CSPS are described by continuum scale parameters determined from atomistic simulations. The framework reproduces all essential features of the atomic scale fracture, including bifurcation, arrest, renucleation, deflection, and penetration. Results reveal that "crystallographic anisotropy" controls the local anisotropy in the propagation pathway, whereas "structural anisotropy" controls the path deviation from the symmetry plane. The fracture pattern emerges from a competition between structural and crystallographic anisotropy effects and long-range elastic interactions among the stress-concentration sites. The underlying physics in high-symmetry configurations is well-explainable using "bifurcation diagrams." [ABSTRACT FROM AUTHOR]

Nanoparticles play an important role in the properties of metallic glasses (MGs) due to their diversified structures; however, their structure–property relationship is unclear. In this paper, three ex situ metallic glass matrix composites were assembled by three kinds of nanoparticles and Cu50Co50 MG obtained by rapid cooling, and their structural evolution under uniaxial compression is investigated by molecular dynamic simulation. It is found that the activated atoms always preferentially accumulate in the amorphous region near the embedded nanoparticles (ENPs). ENPs hinder the propagation of shear bands and lead to strain-hardening behavior. The fractal structures convert the HCP and tDh atoms into atoms of other structures to improve the anti-deformation ability, and the parallel-twin structure improves the anti-deformation ability through the mutual conversion of the FCC and HCP atoms. These findings provide a new idea for improving the mechanical properties of MGs. The change in the ENP structure provides theoretical support for the design of composite materials with specific requirements for structural evolution. [ABSTRACT FROM AUTHOR]

Composite materials use recently increased, although treatments at their End of Life are inexistent or highly inefficient (from the environmental perspective). Thus, openness to cooperation is needed, supported by methodologies for design for de-manufacturing. The approach proposed in the present work aims at transforming industrial processes' scraps and off-specification pieces in primary materials, through re-design, without the risk of cannibalisation. It is mainly intended for industrial processes of composite materials; its objective is to find alternative applications to their invaluable final disposal and supports the merging of existing supply chains (Industrial Symbiosis). Nevertheless, it can be easily extended to non-composite and/or non-scraps. Re-design enables the establishment of waste-to-treasure composite scraps' life cycles and is evaluated through Life Cycle Assessment. The application of the approach involved four Italian companies and results reveal that industrial symbiosis can reduce emissions (from −45% to more than −90%). Guidelines were outlined: involve End of Life operators to know how waste treatments, share information, favour networking and proximity, apply design for disassembly principles, consider simple shapes and modularity during (re)design. Future works will focus on off-the-shelf components and the economic evaluation of the proposed de-manufacturing actions and supply strategies. [ABSTRACT FROM AUTHOR]

The increasing electromagnetic pollution due to the widespread use of electronic devices has drawn attention to the development of high-efficiency electromagnetic wave absorption materials. In this study, polypropylene (PP)/Ni composite materials were prepared using the fused deposition modeling method, with PP as the matrix. The mechanical and absorption properties were investigated, showing that the PP-based materials exhibited good mechanical performance with a tensile strength of 25.3 MPa and an elongation at break of 32.1%. At a Ni content of 50% and a thickness of 1.9 mm, the composite material showed absorption properties of −24.31 dB and 5.6 GHz. The absorption bandwidth covered the entire X and Ku bands (6.4–18 GHz) with adjustable thickness ranging from 1.5 to 4 mm. The combination of excellent absorption and mechanical properties makes these materials promising for the fabrication of complex absorber devices. [ABSTRACT FROM AUTHOR]

The preparation of TC4/7075 composites for ultra-thin flyer plates is a significant challenge in the field of explosive welding. A weldability window for multi-layer metal explosive welding and a configuration for ultra-thin flyer plate explosive welding were established in this study. TC4/7075 composite materials were successfully prepared with a flyer plate thickness of only 0.3 mm. An analysis was conducted on the material bonding ability, element diffusion, crystal evolution, and microscopic morphology during the explosive welding process of TC4/7075, utilizing the weldability window, molecular dynamics algorithm, and electron backscattered diffraction testing. The results show that various dislocations are present at the interface, predominantly 1/6 ⟨112⟩ dislocations. Element diffusion primarily occurs during the unloading stage at high temperature and zero external pressure; the interface has the best bonding ability when titanium exhibits FCC lattice structure. The prepared composite material demonstrates high intra-grain and grain boundary stresses; the rolling texture is observed on the aluminum side while an equiaxed twin structure forms on the titanium side due to interactions between stacking faults, Stair-rod dislocations, and Hirth immovable dislocations. [ABSTRACT FROM AUTHOR]

Metal ion-induced water pollution is attracting increasing public attention. Perovskite quantum dots and metal–organic frameworks (MOFs), owing to their outstanding properties, hold promise as ideal probes for detecting metal ions. In this study, a composite material, MAPbBr3@PCN-221(Fe), was prepared by encapsulating MAPbBr3 quantum dots with PCN-221(Fe), demonstrating high chemical stability and good reusability. The composite material shows a sensitive fluorescence turn-on signal in the presence of silver ions. The fluorescence intensity of the composite material exhibits a linear relationship with the concentration of Ag+ in the solution, with a low detection limit of 8.68 µM. Moreover, the fluorescence signal exhibits a strong selectivity for Ag+, enabling the detection of Ag+ concentration. This fluorescence turn-on signal originates from the Ag+-bridged energy transfer from the conductive band of MAPbBr3 to the excited state of the MOF, which is directly proportional to the concentration of silver ions. Simultaneously, this finding may open up a new possibility in artificial controlled energy transfer from perovskite to MOF for future development. [ABSTRACT FROM AUTHOR]

The graphene-based electromagnetic wave absorption materials have attracted extensive attention due to their lightweight, strong absorption, broadband, and thin thickness. In this work, graphene hollow microspheres anchored with FeNi-coupled nanocrystal (GHMs@FeNi3/NiFe2O4) were synthesized using water-in-oil (W/O) emulsification and high-temperature calcination. The GHMs@FeNi3/NiFe2O4 microspheres have a homogeneous spherical morphology and a pronounced hollow structure, and the FeNi-coupled nanocrystals are homogeneously embedded in a spongy shell assembled by rGO nanosheets. Owing to the optimized impedance matching and enhanced attenuation, the GHMs@FeNi3/NiFe2O4 composites exhibit outstanding microwave absorption ability, particularly in the Ku band. The minimum reflection loss (RLmin) value can reach −58.96 dB at 14.43 GHz with a matching thickness of 2.25 mm, and the effective absorption bandwidth (lower than −10 dB) is up to 6.29 GHz (11.71–18 GHz) covering the whole Ku band. We believe that our work provides an idea for the design of high-performance absorbing composite materials. [ABSTRACT FROM AUTHOR]

Active thermography using pulsed heating is a fast and reliable method for detecting flaws in composite and metallic materials. This paper analyzes the temperature decay that occurs immediately after flash heating the front surface of stainless steel specimens as a function of time, based on a novel application of the equivalent circuit approach (ECA). The temperature decay from the front surface is equated to the discharge of a capacitor. The ECA is based on the charging (temperature rise due to flash heating) of a capacitor, followed by its discharge (temperature decay) through a series of resistors (which depends on the conductivity of the material) and capacitance (which depends on the thermal capacitance of the layers) through which the heat is dissipated. The proposed approach analyzes the sequences of temperature data obtained at each pixel location during cooling from a step wedge and a specimen with multiple flat-bottom holes. Time constant maps derived from the analysis are used to ascertain the thickness of the step wedge, detect the flaws, and evaluate the remnant thickness of the flaws. A correlation has been established between the thickness and the time constants. The above approach has been used to estimate the diameter of the flat-bottom holes. [ABSTRACT FROM AUTHOR]