查看更多>>摘要：? 2022 Elsevier B.V.Establishing the relationship between microstructures and mechanical properties of metallic glasses (MGs) is of great significance for guiding its application. Therefore, four groups of Mg65Cu25Y10 MGs with the same size were obtained by rapid solidification at four pressures by molecular dynamics (MD) simulation in this paper, and uniaxial compression were performed. The results show that the volumes of shear transformation zones (STZ) of four models increase sequentially. The average atomic potential energy increases, and the plasticity increases. The smaller the non-affine displacement (NAD), the higher Top-10 Topologically close-packed (TCP) and defective TCP clusters, which are the main structural units of MGs. Medium-range ordered (MRO) nanoclusters composed of their interconnections, are broken into small-sized nanoclusters during compression. Regions with large-sized MRO nanoclusters tend to be "stiffer", making these regions difficult for large-scale structural rearrangement and plastic flow. The deformation resistance of these regions is thus improved. Chain-like nanoclusters are easier broken during compression, and MRO nanoclusters linked with larger bond numbers can withstand greater strain for enhancing their plasticity. These findings have excellent theoretical guidance for promoting plasticity in MGs.
查看更多>>摘要：? 2022 Elsevier B.V.Polyaniline-derived carbon (PDC) and Ni3Fe composites for electromagnetic wave (EMW) absorption were prepared through in-situ polymerization and carbonization. Using polyaniline as carbon source not only realized the doping of carbon with nitrogen, but also allowed homogeneous dispersion of Ni3Fe nanoparticles to achieve multiple reflection interfaces. The content of Ni3Fe can be used to control the impedance matching of the composites, while the dual loss mechanism of dielectric loss and magnetic loss was realized to promote EMW absorption performance. The polyaniline-derived carbon/Ni3Fe (PDC/Ni3Fe) nanocomposite with optimized composition had a minimum reflection loss (RL) of ? 80.91 dB. A maximum effective bandwidth of 6.10 GHz (11.90 ?18.00 GHz) was achieved, while the thickness is 2.12 mm.
查看更多>>摘要：? 2022 Elsevier B.V.In this work, the porous o-(Co,Fe)Se2/Ti2C MXene composite microspheres have been prepared using a facile and simple strategy via in-situ growth of orthorhombic o-(Co,Fe)Se2 on few-layered Ti2C MXene and subsequent vacuum calcination. The porous o-(Co,Fe)Se2/Ti2C composite microspheres exhibits a high reversible capacity of 286.2 mA h g–1 at a current density of 1 A g–1. In addition, the assembled asymmetric supercapacitor demonstrates a competitive energy density (68.9 Wh kg–1 at 800.0 W kg?1) and a robust long cycling stability (65.3 % capacitance retention after 10,000 cycles). The excellent electrochemical performance is described to the unique architecture of porous o-(Co,Fe)Se2/Ti2C microspheres and the synergistic effect of Fe doping and compositing with MXene.
查看更多>>摘要：? 2022 Elsevier B.V.A new process of accumulative roll bonding-deformation diffusion (ARB-DD) with subsequent deformation diffusion heat treatment was proposed to solve the problem of poor composition homogeneity of alloys prepared by conventional accumulative roll bonding-diffusion heat treatment (ARB-DHT). The effects of ARB-DHT and ARB-DD on compositional homogeneity of Cu-Ti alloys were studied in comparison. And the mechanism of compositional homogeneity evolution of ARB-DDed Cu-Ti alloy was revealed. The results show that elements in Cu-Ti alloys prepared by the conventional ARB-DHT process are enriched and show a more obvious periodic distribution characteristic, and the compositional homogenization is poor. However, in ARB-DD process, the deformation process drives the Taylor lattice to reopen and form high-density nano-twin with a lamella width of 50–90 nm. Further, the high density of dislocations and stacking faults provides high diffusion rate channels for element diffusion, which effectively facilitates the diffusion and redistribution of elements in the subsequent diffusion heat treatment process and accelerates the compositional homogenization. On the contrary, in comparison with the conventional ARB-DHT process which promotes element diffusion through thermal effects, the ARB-DD process uses the synergistic effects of thermal and deformation effects to promote element diffusion, effectively enhancing the degree of compositional homogenization.
查看更多>>摘要：? 2022 Elsevier B.V.In this study, finite element analysis was performed using representative volume elements (RVE). The cohesive zone model was implemented to govern the failure behavior of the CNTs/matrix interface. The RVE to understand the micromechanical response and damage behavior of randomly distributed carbon nanotubes (CNTs)/Mg matrix composites (MMCs). The cohesive zone model was implemented to govern the failure behavior of the CNTs/Mg interface. The RVE for macroscopic structural analysis was strained under assumed boundary conditions, where it provided a stress-strain curve for the composite. The simulation data can achieve excellent agreement with the experimental results. The simulations and experimental results indicate that the initial damage in the composite occurs in the vicinity of CNTs. The stress concentration at the CNT end increases with the increasing tensile load, resulting in interfacial debonding, the main form of crack growth of the CNTs/Mg composite. The CNTs can passivate the crack tip and change the propagation direction of the main crack, causing a delay in fracture. CNTs played an important role in governing the fracture pattern of composite. The pullout and bridging of CNTs were the main strengthening mechanisms of the composites, which was beneficial for improving strength and toughness.
查看更多>>摘要：? 2022 Elsevier B.V.CdS conductor has a suitable band gap (~2.4 eV), and the energy band position is conducive to photocatalytic CO2 reduction. However, its photocatalytic efficiency is highly confined by its unfavored carrier transfer. In this study, a moderately in-situ growth method is harnessed to insert commercial TiO2 particles (P25) into the CdS grains in the first place, and the resulted CdS-P25 composite is further integrated with to a mixed-ligand-based metal organic framework (MOF), CuTCPP?UiO-66 (CTU), which is structure-analogous to regular UiO-66 MOF but with visible light response thanks to the involvement of copper(II) tetra(4-carboxyphenyl) porphyrin (CuTCPP) ligand. The eventually attained ternary composite (CTU/CdS-P25) by solvothermal approach presents a broadened light absorption and an impressive delivery for photo-induced carriers. The light-driven catalytic assessment of CTU/CdS-P25 for CO2 reduction furnishes the CO production rate as great as 2.38 μmol·h?1, as much as 3.9 and 8.8 times that of UiO/CdS-P25 and CdS-P25, respectively. According to the value determination of band edge for each component of the ternary composite, we proposed that the established heterojunction facilitates a cascade electron transfer mode within the structure, which highly suppresses the adverse recombination of carriers and thereafter significantly enhances the photocatalytic behavior. Our work provides an effective perspective for the melioration of CdS semiconductor.
查看更多>>摘要：? 2022 Elsevier B.V.ZnO-In2O3-SnO2 (ZITO) thin film library was produced via the combinatorial approach. The films were deposited using a magnetron sputtering system. Varying ZITO compositions were obtained in a single deposition run by employing a custom-made triangular type of substrate carrier magazine. The effect of various postgrowth annealing atmospheres on the electrical and optical properties of the films were examined. Air, Ar, forming gas (Ar+4 vol% H2), and successive annealing under forming gas + argon atmospheres were studied. Room temperature (RT) deposited films were identified either crystalline or amorphous depending on the location of the substrate on the holder. All these samples exhibited average visible transmittance (Tvis) below 75 % and sheet resistance (RS) higher than 50 Ω/□. Annealing under air atmosphere improved the optical and electrical properties of the films significantly, but not simultaneously for the same composition. Although better optical improvement was achieved by annealing under Ar and increase in electrical conductivity after annealing under forming gas, optimum properties have been obtained with the latter condition. Tvis values above 85 % and RS values below 50 Ω/□ were attained. On the other hand, successive annealing did not provide any advantage in reaching optimal samples when compared to single gas atmosphere annealings. Further, increasing the annealing temperature were found to be beneficial particularly for the conductivity of many compositions. Finally, this study has introduced a systematic approach to produce transparent conductive oxide thin films with reduced indium content that can be suitable for many optoelectronic applications.
查看更多>>摘要：? 2022 Elsevier B.V.(AlCrMoTaTi)Nx nano-multilayer coatings with different N concentration were deposited by varying the nitrogen flow rate using a closed field unbalanced magnetron sputtering. With the nitrogen flow rate increased from 0 sccm to 16sccm, the phase structure changed from a HCP metal phase to a mixed phase of HCP metal and FCC nitride, and then to a fully FCC nitride phase similar to B1-NaCl at the nitrogen flow rate above 12sccm. The (AlCrMoTaTi)Nx coatings formed nano-multilayer super lattice structure with modulation periods of about 2 nm. The FCC structured (AlCrMoTaTi)Nx coatings exhibited hardness ranging between 32.8 and 35.2 GPa, which was related to their superlattice structure with a small modulation period and the inverse Hall-Petch soften effect due to their small grain sizes. The FCC structured (AlCrMoTaTi)Nx coatings also exhibit higher H/E* ratios above 0.09 than that of monolayer binary, nano-multilayer and high entropy nitride coatings, which can be attributed to their moderate valence electron concentration that can not only preserves the formation of strong Me-N bonds but also enables the formation of Me-Me bonds.
查看更多>>摘要：? 2022 Elsevier B.V.Introducing Laves phase into refractory high entropy alloys is a new exploration direction to improve the alloy strength. The as-cast and annealed states ZrNbTaHf0.2Crx (x = 0, 0.3, 0.5, 0.75, 1.0) alloys were prepared, and the microstructure, phase constituents, and mechanical properties of the refractory high-entropy alloy were studied in the present work. The addition of Cr elements affects the alloy properties mainly through the formation of the high-entropy Laves phase. The ZrNbTaHf0.2Crx alloys have a typical dendritic structure, consisting of BCC solid solution phase, HCP solid solution phase and C15 Laves phase. With the increasing Cr content, the fraction of Laves phase increases significantly. The heat treatment results in more fraction of the C15 Laves phase and BCC phases. After annealing, the growth of BCC phase has no obviously preferred orientation. The hardness and strength significantly increase with Laves phase with a compromise in ductility. The solid solution strengthening caused by significant lattice distortion and laves phase precipitation increase the strength and hardness of the alloys.
查看更多>>摘要：? 2022 Elsevier B.V.Due to their high band degeneracy and intrinsic low lattice thermal conductivity, n-type Mg3Sb2-based thermoelectric materials have drawn a lot of attention in thermoelectric applications in recent years. By using simple and efficient fast induction melting and hot pressing, the n-type Mg3.5?xNixSbBi0.96Te0.04 (x = 0, 0.015, 0.02, 0.03, 0.04, 0.05, and 0.06) samples have been successfully synthesized. The structure of Mg3.5?xNixSbBi0.96Te0.04 samples is examined, as well as their thermoelectric properties. The findings demonstrate that the mixed valence of Ni2+ and Ni3+ that occupied distinct Mg sites occurred as the Ni doping level grew in the Mg3.5?xNixSbBi0.96Te0.04 samples. The trivalent Ni3+ increases carrier concentrations dramatically, while the divalent Ni2+ increases the effective mass. The mixed valence of Ni causes lattice disorder, which enhances phonon scattering and reduces lattice thermal conductivity. As a result, the Mg3.485Ni0.015SbBi0.96Te0.04 sample has a high ZT value of 1.58 at 743 K and an average ZT value of 1.22 from 323 to 743 K. This work suggests that the mixed valence of cationic dopant effectively improve the thermoelectric performance of n-type Mg3Sb2-based compounds.
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