查看更多>>摘要：A new titanium matrix composites (TMCs) with distinctive architecture consisting of isolated fiber-like structural composites region (FLSCR) within continuously Ti region were designed and fabricated by powder metallurgy, hot extrusion, and subsequent hot rolling. This work systematically investigated the important role of TiB contents on microstructural evolution and mechanical response of the as-rolled fiberlike structural TMCs. The designed FLSCR-5% and FLSCR-10% with fiber-like structure obtain high ductility of 24.4% and 19%, respectively, which shows a better combination of strength and ductility. The strengthening is attributed to the refinement of the equiaxed alpha grains and the load-bearing effect of TiB whiskers. Meanwhile, continuously Ti region significantly reflects and blunts the crack propagation which is supposed to improve the static toughness of the fiber-like structural TMCs, but the ductility would be decreased by increasing TiB content in the FLSCR, which is attributed to the decreasing volume fraction of titanium matrix and the increasing crack initiation rate. Additionally, due to the fiber-like composites region, the strain hardening rate of the FLSCR-10% (from ~0.05 to ~0.135 strain) is significantly strengthened by the hetero-deformation induced back stress, which is beneficial to the ductility. (c) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：The plate-like Fe-rich intermetallics phases in the recycled Al-Si alloys significantly deteriorate the mechanical properties. In this study, the effect of Mn addition on Fe-rich phases formation and the properties of the Al-7Si-1.2Fe alloys were systematically studied by optical microscopy, scanning electron microscopy, differential scanning calorimetry, thermodynamic calculations, synchrotron X-ray radiography and tomography. The results show that with the addition of Mn, the two-dimensional (2D) morphology of the Fe-rich phase change from plate-like to Chinese-script and star-like. The synchrotron X-ray tomography results indicate that the three-dimensional (3D) morphology of Fe-rich phases change from interconnected platelike to separated hollow polyhedron with increasing Mn content. The in-situ synchrotron X-ray radiography results reveal that the formation temperature, size, and area fraction of the primary Fe-rich phase in the Al7Si-1.2Fe-1.09Mn alloy gradually decreased, but the number density increased as the cooling rate increased. The thermodynamic calculation results indicate that beta-Al5FeSi could be eliminated when the Mn content exceeded 1.06%, which was consistent with the experimental results. However, excessive Mn addition caused the formation of large primary Fe-rich phases, resulting in a significant reduction in the elongation of the alloys. Reducing the equilibrium partition coefficient difference of Mn and Fe and reducing the formation of primary Fe-rich phases with high Mn/Fe ratios are good strategies to neutralize the negative effect of Fe-rich phases. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：The localized surface plasmon resonance effect (LSPR) with kinetic energies and interfacial transfer dynamics can highly improve the separation of photo-generated carriers. We demonstrate here that a plasmonic catalyst Au-Pt-SiC has been prepared by a facile reduction-photo-deposition technique. The Pt-Si bond is formed on the SiC surface to construct an excellent channel for accelerating photo-electrons transfer from SiC to Pt. The LSPR of Au with electrons-deficiency property further activates the anchored Pt-Si bond, and motivates an oriented high-efficient photo-electrons transport channel among the Au, Pt and SiC. This channel accelerates the excited electrons in SiC to transfer to cocatalysts and thus improves the photo-generated charge carriers separation. The LSPR of Au also harvests light energy efficiently to broaden the light absorption range. Consequently, the rate of photocatalytic water reduction for H-2 is enhanced to 2248.5 mu L h(-1) g(-1) in Au-Pt-SiC, 2.1 times higher than that of the individual Pt loading. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Superior electromagnetic (EM) wave absorption properties in 8.2-12.4 GHz (X-band) can be obtained via the effective combination of polyaniline (PANI) and SnO2 nanoparticle cluster. In this work, SnO2 nanoparticle cluster@PANI (SnO2@PANI) core-shell microspheres were firstly fabricated via a hydrothermal process followed by in-situ polymerization, and the EM wave absorption properties of SnO2@PANI coreshell microspheres in X band were studied. The related structure and morphology analyses indicated SnO2@ PANI core-shell microspheres were successfully synthesized with PANI coated on the surface of SnO2 nanoparticle cluster. The minimum reflection loss (RLmin) of - 69.1 dB (thickness of 2.78 mm) and effective absorption bandwidth (EAB) covering the whole X-band (when the thickness was from 2.5 to 3.1 mm) was achieved. Remarkable EM wave absorption properties of SnO2@PANI core-shell microspheres were mainly attributed to the outstanding impedance matching characteristic and dielectric loss capability (conduction loss, interfacial polarization loss and dipole polarization loss).
Paul, ShiddarthaSchwen, DanielShort, Michael P.Erickson, Anna...
10页
查看更多>>摘要：Multimetallic layered composites (MMLCs) have shown an excellent potential for application under extreme environments, e.g., accident-tolerant fuel cladding, because of their low oxidation tendency and high corrosion resistance. Interfacial phases or complexions in nanocrystalline materials accelerate the annihilation of defects and enhance the radiation resistance of materials, making MMLCs with engineered interlayer phases compelling to deploy in extreme conditions. However, implementation of MMLCs in full capacity remained a challenge due to a lack of fundamental understanding of the underlying mechanisms governing the characteristics of the interface between the metallic layers. The precise role of interlayer phases in MMLCs and their interaction with defects, specifically under extreme conditions, is still unexplored. Pursuing atomistic simulations for various Inconel-Ni MMLCs model materials, we revealed accelerated defect mobility in interlayers with larger crystalline misorientation and the inverse relationship between the interface sink strength to the misorientation angle. Furthermore, we found a linear relation between interlayer misorientation angle with the density of radiation-induced defects and radiation enhanced displacements. Finally, our results indicate that radiation-induced material degradation is accelerated by the higher defect formation tendency of MMLCs with a high-angle interlayer interface.(c) 2022 Elsevier B.V. All rights reserved.
Sharma, Pradeep KumarSenguttuvan, T. D.Sharma, V. K.Patro, Pankaj...
10页
查看更多>>摘要：Thermoelectric materials are promising as they found numerous applications in electrical power generation and solid-state cooling. In the last decade, Lead Telluride (PbTe) has emerged as a potential thermoelectric candidate for electrical power generation in the medium temperature range. In the present work, we demonstrate nearly 78% enhancement in thermoelectric figure of merit (zT) of nanostructured PbTe compound through doping with bismuth and dispersing 50 nm SiC nanoparticles. Bismuth doping induces n-type conduction and improves the electrical conductivity, while the SiC nanoinclusions modulate the Seebeck coefficient by carrier energy filtering, in addition to suppressing the lattice thermal conductivity. The significant phonon scattering at multi-scale scattering centers resulted in a minimum lattice thermal conductivity (kappa(L)) of 0.69 W/m-K in Bi-0.02-Pb0.98Te-8% SiC nanocomposite sample. Finally, the reduced lattice thermal conductivity in conjunction with moderate electrical conductivity and high Seebeck coefficient leads to a zT(max) value of 0.32 at 590 K in the sample with 6% SiC content. Hence, the partial substitution of the host atom and the presence of a secondary phase can be another promising strategy to enhance the thermoelectric performance. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Ferroelectric (FE) materials, owing to their remarkable photovoltaic effects, are one class of the most promising materials candidates for self-powered photodetectors. Here, with the pronounced rectification ratio as large as 10(3) at electric bias of & PLUSMN; 1.0 V and a low dark current of 12 pA, the self-polarized Bi0.9Eu0.1FeO3 (BEFO)/Nb-doped SrTiO3 (NSTO) p-n heterojunctions are synthesized. It is revealed that the BEFO/NSTO p-n heterojunctions achieve the excellent photovoltaic effect with a short-circuit current as high as 0.23 mu A and an open-circuit voltage of 0.41 V under the light illumination of 405 nm in wavelength and intensity of 151.7 mW/cm(2). More importantly, the built-in potential in the as-prepared heterojunctions offers the self-powered photo-detecting functionality, with the high light-on/off current ratio of 2.0 x 10(4), high responsivity of 0.64 mA/W and sensitive detectivity D* of 1.63 x 10(10) Jones, and fast response speed of 50/44 ms without external bias voltage. In particular, the super-performance with R ~ 1.97 mA/W and D*~ 5.0 x 10(10) Jones in the weak incident light intensity (1.4 mW/cm(2)) are demonstrated, better than most previously reported FE-based self-powered photodetectors. Moreover, the devices possess good ambient stability and reproducibility. This work provides a demo for optically driven high-performance electronic devices based on self-polarized ferroelectric materials. (c) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：This paper focuses on the corrosion behavior of Mg-5.7Gd-1.9Ag alloy sheets with high strength-ductility synergy in the 3.5 wt% NaCl solution prepared by a combined route of rolling and aging. Electrochemical measurements indicate that the rolled sheet exhibits a significantly improved corrosion resistance as compared to its as-cast counterpart. Subsequent aging, as a widely used strengthening method, decreases corrosion resistance to a certain extent. However, the aged sheet still has enhanced corrosion resistance as compared to its as-cast counterpart. The observed corrosion migration in the present Mg-5.7Gd-1.9Ag Mg alloy mainly stems from the evolution of second phases, but not the grain size and texture. A small number of the micron beta phase particles is incapable of promoting severe galvanic corrosion and thus endows the rolled sheet with good corrosion resistance, while the massive submicron beta phase particles along grain boundaries and dense gamma '' nanoplates within grains in the aged sheet bring out severe galvanic corrosion and thus accelerate corrosion. (c) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：Si(3)N(4 )nanowires doped with rare earth ions (such as Ce3+, Tb3+, Eu2+ and Eu3+) were synthesized by plasma assisted direct nitridation method using Si, rare earth oxides and N2 as raw materials. The prepared doped Si(3)N(4 )nanowires were characterized by XRD, EDS, XPS, SEM and TEM. The obtained single-crystal doped Si(3)N(4 )nanowires have uniform diameters of about 50-100 nm and lengths of more than 10 mu m. The photoluminescence (PL), PL decay curves as well as thermal quenching behaviors of doped Si3N3 nanowires were systematically investigated. This work provides an effective strategy for doping large-size functional atoms in Si(3)N(4 )nanowires. (C) 2022 Elsevier B.V. All rights reserved.
查看更多>>摘要：The hot deformation behavior and microstructural evolution of Inconel 625 superalloy sheet under different conditions were investigated. The hot tensile tests under the temperature ranging from 800 degrees C to 950 degrees C with the increment of 50 degrees C and the strain rates between 0.001 and 0.1 s-1 were performed on a Gleeble 3500 machine. The experimental results indicated that the plastic flow behavior of the Inconel 625 sheet changes from work hardening to hot softening with the rise of experimental temperature and the decline of strain rate. Furthermore, the elongation is decreased with the rise of deformation temperature and decline of strain rate. According to the principle of dynamic material model (DMM), the process maps at various strains were constructed, and the optimal domain with the highest power dissipation was determined. The optimal domain appears at the temperature range of 925 and 950 degrees C and the strain rate between 0.001 and 0.1 s-1 with the power dissipation efficiency of about 46.5%. The grain size, grain boundary and texture of the deformed samples under typical conditions was analyzed by electron backscatter diffraction (EBSD) and transmission electron microscope (TEM), which reflected that the dynamic recrystallization (DRX) occurs in the optimal hot working window, and the preferred orientation for DRX nucleation of the Inconel 625 superalloy sheet is the < 001 > direction. The deformation behavior of Inconel 625 sheet under the longterm service temperature range is affected by the coupled effect of DDRX and CDRX. (c) 2022 Elsevier B.V. All rights reserved.
NSTL
Elsevier