查看更多>>摘要：? 2022 Elsevier B.V.Here, a new Mg-1Bi-1Mn-0.3Zn (BMZ110, wt%) wrought alloy designed by the dilute addition of Zn subjected to an appropriate extrusion processing that showed an excellent strength-ductility synergy at room temperature. The main results included four aspects as follows: 1) With dilute Zn addition, the as-cast BMZ110 alloy was refined into an approximately equiaxed-grained structure, since the solid solution of Zn provided a relatively high growth restriction factor. 2) The as-extruded BMZ110 alloy exhibited the finer average grain size and weaker basal texture intensity than the as-extruded BM11 alloy without Zn. The co-segregation of Bi and Zn solutes into grain boundaries was observed to impede grain growth during extrusion and further weaken texture intensity. Moreover, Zn atoms incorporated into Mg3Bi2 phases by replacing Bi atoms increasing the nucleation rate of Mg3Bi2 phases and refining their sizes. 3) Compared with the as-extruded BM11 alloy, the as-extruded BMZ110 alloy demonstrated the higher yield strength (~ 283.4 MPa), ultimate strength (~ 366.2 MPa) and elongation-to-failure (~ 26%). The size refinement of grains and second phases contributed to an extra strength increments. Grain boundary segregation enhanced grain boundary cohesion not only reducing the number density of grain boundary cracks, but also activating more slip modes and grain rotation for increasing the ductility. 4) The as-extruded BMZ110 alloy had the higher grain growth resistance than the as-extruded BM11 alloy during annealing. Solute segregation offered an effective obstacle to restrict grain boundary migration enlarging the activation energy (~ 112.2 kJ/mol) and further delaying the grain growth. Therefore, this work will be helpful for the development of new high performance low-alloyed Mg-Bi based wrought alloys to achieve extensive applications in industries.
查看更多>>摘要：? 2022 Elsevier B.V.Hydrogen evolution via dye-sensitized photocatalytic water reduction is a promising approach for storing solar energy due to high efficiency and good stability. The hydrophilic and electrical performances of sensitized matrix are critical for the reactant adsorption and photogenerated charge transport. Herein, theoretical simulation proves that the boron-doping nanoarchitectonics on three-dimensional carbon nanosheets (B-3DCNs) as a new-style sensitization matrix possesses a strong water adsorption capacity to show a stable disperse in water, as well as optimizes charge distribution to improve conductivity compared with pure material. So the boron dopants on the substrate surface can be used as an anchor for water and a booster for charge transfer. Based on the theoretical results, B-3DCNs with abundant and stable boron atoms is prepared by a solid-phase thermal doping technology using sodium borohydride as boron source. The hydrophilic and electrical properties of B-3DCNs is greatly optimized using a series of structural and performance testing, providing the prerequisite for large-scale applications in aqueous solution. Therefore, the constructed B-3DCNs/Pt photocatalyst displays a high photocatalytic hydrogen evolution rate under visible light in Eosin Y sensitized system, which is 5.9 and 2.3 times than the H2 evolved over bare Pt and 3DCNs/Pt.
查看更多>>摘要：? 2022 Elsevier B.V.Lithium-oxygen (Li-O2) batteries are facing challenges in capacity, cycling stability, and kinetics for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Advanced catalysts should have a high and bifunctional catalytic activity for ORR and OER. Moreover, the trade-off carbon in catalysts should have good oxidation resistance and high electronic conductivity and be used in a tiny amount. Up to now, it is still a challenge. Therefore, this work introduces a low-carbon CeOx/Ru@RuO2 nanosheet as efficient cathode catalysts for Li-O2 batteries and studies the preparation and working mechanisms using a variety of characterization and electrochemical techniques. The air oxidation treatment oxidizes Ru into Ru@RuO2 and simultaneously removes unstable C into CO2, leaving a tiny amount of stable carbon. CeOx/Ru@RuO2 has enormous mesopores, well-distributed sub-5 nm CeOx and Ru@RuO2 nanocrystals, a tiny amount of anti-oxidation carbon (1.2 %), and a high specific surface area of 159.3 m2 g?1. These aspects optimize the Li-O reaction and regulate the Li2O2 nucleation to form uniform and ultrathin Li2O2 nanoflakes. As a result, the ORR and OER overpotentials are only 0.17 V and 0.45 V, respectively. This work provides a novel material combination and structure design for developing bifunctional catalyst materials in Li-O2 batteries.
查看更多>>摘要：? 2022 Elsevier B.V.The novel Al-Ce alloys were designed with the addition of Cu and Mg elements using laser melting. The microstructure and high-temperature mechanical properties of the novel Al-Ce alloys were studied in this paper. The results showed that the laser melted Al-12Ce alloys are composed of eutectic α-Al and Al11Ce3 phases. The addition of Cu can refine the primary phase of Al-Ce alloys by forming the (Al,Cu)11Ce3 participation, while the Mg element mainly produces solid solution strengthening. The addition of Cu and Mg elements can significantly increase the room mechanical properties of eutectic Al-Ce alloys. The hardness of laser melted Al-12Ce-3Cu-2.4Mg alloys is 116.42% higher than that of traditional Al-12Ce alloys. At 300 ℃, the tensile strength (TS) of Al-Ce alloys with different compositions can be maintained at 80% of room temperature and the elongation (EI) is significantly increased. Therefore, the Al-Ce-Cu-Mg alloy system is expected to be a new heat-resistant alloy widely used.
查看更多>>摘要：? 2022 Elsevier B.V.The effect of homovalent Tb/Y and Zn/Cu substitution on electrical, superconducting, structural, and magnetic features of Y-123 ceramic materials is extensively examined by powder X-ray diffraction, electrical resistivity, scanning electron microscopy, energy dispersive X-ray spectrometry, DC magnetization VSM measurements and related calculations. Y1?xTbxBa2Cu3O7-? and YBa2(Cu1?xZnx)3O7-? samples are prepared with four different molar percentages (0.0 ≤x ≤ 0.15) using the sol-gel technique. DC magnetization data and the Bean model are used to evaluate change in critical current densities with an applied magnetic field. Energy-dispersive X-ray spectrometry measurements indicate that materials are exactly produced in the desired stoichiometric ratios. Moreover, all the experimental findings show that the fundamental characteristic properties are observed to decrease with replacement mechanism. The degradation mechanism with partial substitution is thoroughly explained scientifically in the basic contents for the first time. The role of Tb/Y and Zn/Cu partial substitution on the oxygen concentration level in unit cell, ordering degree in the Cu-O ribbons, lattice cell parameters, grain size, and the number of holes in the σ antibonding in-plane Cu-O bonds are also discussed in detail. Additionally, beginning of weak-interaction problems between adjacent superconductive layers, formation of microscopic structural faults and decoupling of superconducting grains are noted to be the negative effect of substitution mechanism. Regardless, it is observed that Tb-doped samples possessing more uniform surface morphologies with better surface texture and connection quality between particles show much higher magnetization behavior and superconducting properties. All in all, this study developing a scientific methodology about why fundamental characteristic features change with the partial replacements of Tb/Y and Zn/Cu in crystal systems seems a pioneering investigation to construct novel and feasible application fields for the Y-123 ceramic compounds.
查看更多>>摘要：? 2022 Elsevier B.V.In the present study, the liquidus temperature, mixing enthalpy, and atomic mismatch factor are used to predict and empirically evaluate the amorphisation capability of Co-Fe-B alloys fabricated by melt spinning. Based on this approach, five out of seven alloys have an amorphous structure, confirming the capability of the proposed model in predicting the alloy compositions with higher amorphisation ability in a ternary alloy system in the absence of any costly elements, such as Nb, Mo and Zr. X-ray diffraction, TEM and M?ssbauer results show that the other two alloys exhibit different in-situ crystallisation behaviour. In one case, only the free-side crystallises, whereas the crystallisation occurs through the entire thickness of the ribbon in the other alloy. The lower amorphisation ability exhibited by these alloys in relation to the predictive parameters has been evaluated. Additionally, there is a strong correlation between amorphisation ability and crystallisation behaviour of alloys. Alloys, which crystallise through eutectic mode, are more likely to exhibit high amorphisation capability, whereas crystallisation via the primary mechanism can be the sign of lower amorphisation ability. The output of the alloy design process is five amorphous compositions, among which one is magnetically ultra-soft, Hc = 2.9 A/m; a surface crystalline alloy, with a low coercivity and higher value of anisotropy field compared to amorphous samples; and a nanocrystalline sample with a very high saturation flux density, Bs = 1.57 T. The surface crystallisation can eliminate the need for inducing transverse anisotropy by magnetic annealing. Therefore, optimising the alloy composition through this method can be a universal strategy of composition design for the fabrication of alloys with excellent properties, to be utilised in both high-Bs and low-Hc applications.
查看更多>>摘要：? 2022 Elsevier B.V.The effect of applied stress during ultra-rapid annealing (URA) on the magnetic properties has been investigated for rapidly-solidified (Fe1-xCox)86B13Cu1 (x = 0–0.05) alloys. Nano-meter scale grains with an average size of about 15 nm and a small coercivity value of 5 ± 1 A/m are confirmed for all the alloys after URA at 763 K for 0.5 s. The saturation magnetic polarization (Js) of these nanocrystalline alloys shows a slight increase with Co content from 1.88 T at x = 0 to 1.94 T at x = 0.05. A clear creep-induced anisotropy (Ku) up to 460 ± 20 J/m3 is observed with a hard axis along the direction of applied tensile stress for x = 0–0.04 while an easy axis is confirmed in the same direction for x = 0.05. The saturation magnetostriction (λs) of nanocrystalline (Fe1-xCox)86B13Cu1 increases monotonously from + 13 ± 2 ppm to + 20 ± 2 ppm with an increase of x from 0 to 0.05 and the observed change in the anisotropy axis cannot be attributed to the bulk magnetoelastic effect. The magnetostriction was also measured for polycrystalline Fe1-xCox (x = 0–0.1) binary alloys prepared for comparison and λs of bcc-Fe is confirmed to change its sign from negative to positive by Co addition. A similar trend is confirmed for the local magnetostriction estimated for the bcc-Fe(Co) phase in the nanocrystalline samples by assuming the inverse effect of the local magnetostriction, suggesting that Ku in nanocrystalline (Fe1-xCox)86B13Cu1 (x = 0–0.05) alloys is due to the strain retained within the bcc-Fe(Co) nanocrystallites. Our results demonstrate that the shape of the hysteresis curve in the URA Fe-B based nanocrystalline alloys (HiB-Nanoperm) can be controlled by stress applied to the precursor amorphous ribbons during annealing.
查看更多>>摘要：? 2022 Elsevier B.V.Single-crystalline (SC) high energy nickel (Ni)-rich cathodes play a key role as a potential cathode material in lithium-ion batteries (LIBs) to address the challenges in a hierarchical structure of their secondary particles by decreasing phase boundaries and materials surfaces. The SC LiNi0.78Mn0.12Co0.1O2 (SC-NMC78) cathode with primary particles of several micron-sized particles are developed and thoroughly investigated in this study, demonstrating superior cycling performance, along with significantly enhanced structural reliability after long-term cycling. The improved SC-NMC78 has an octahedral SC morphology with a modest grain size, which reduces the lithium-ion diffusion route and enhances structural stability. The SC-NMC78 offers a high discharge capacity of 175 and 155 mAh g?1 at 0.2 and 1 C, respectively, and better capacity retention of 132 mAh g?1 after 200 cycles at 1 C as a cathode in LIBs. The cycled SC-NMC78 particles exhibited no lattice gliding and micro-cracks, demonstrating that the SC shape may substantially reduce anisotropic micro-strain. This efficient, repeatable, and customizable method for producing SC Ni-rich cathodes without any additives should accelerate their commercialization. The density functional theory also proved that the low global hardness of Ni2+ in SC-NMC78 and optimized content of Ni/Li exchange were well-consistent with the experimental findings.
查看更多>>摘要：? 2022 Elsevier B.V.The present study aims to investigate non-stoichiometric Al1.4Co2.1Cr0.7Ni2.45Si0.2Ti0.14 high entropy alloy (HEA) as a bond coat material for the TBC (Thermal Barrier Coating) system. The mechanical activated synthesized HEA was sprayed on a Ni-based superalloy substrate by High-velocity oxy-fuel (HVOF) spraying, and 8 mol% Yttria Stabilized Zirconia (YSZ) was deposited on HEA by Air Plasma Spray (APS). X-Ray Diffraction (XRD) analysis and Scanning Electron Microscopy (SEM) were used to investigate the phases and microstructure of the as-synthesized HEA powder, Ni superalloy/HEA-bond coat, and Ni superalloy/HEA-bond coat/YSZ topcoat. The mechanical properties of the coating like microhardness, Young's modulus and residual stress between bond coat and YSZ top coat was evaluated using the Nano-Hardness Tester (NHT). The TBC system was investigated for cyclic oxidation at 1050 ℃ for 100 cycles, and its cross-sections were analyzed for TGO (Thermally grown oxides) layer composition, thickness and interdiffusion of elements. The properties of the TBC system containing HEA as a bond coat were compared with those of the conventional TBC system comprising of MCrAlY (AMDRY 365–4) as a bond coat. It was observed that HEA containing TBC displayed exceptional high temperature properties and were comparable to MCrAlY.
查看更多>>摘要：? 2022 Elsevier B.V.Compositing nickel-cobalt layered double hydroxide (Ni-Co LDH) with special materials is a promising strategy to develop high-capacity electrode. But how to overcome the intrinsic defects of Ni-Co LDH by facile methods to obtain superior electrochemical performance is still a challenge. In this work, a multicomponent nitrogen-doped carbon@Ni-Co LDH (N/C@Ni-Co LDH) nanosheet arrays derived from zeolitic imidazolate framework is synthesized via a facile hydrothermal method, which provides three-dimensional open channels for the sufficient permeation of electrolyte. In addition, the N-doped carbon can enhance charge transfer capability and electrolytic accessibility. The N/C@Ni-Co LDH electrode exhibits an ultrahigh specific capacity of 405.5 mAh g?1 (2920 F g?1) at 1 A g?1. When it is served as the positive electrode in an asymmetric supercapacitor (ASC) of N/C@Ni-Co LDH//AC, the ASC reaches a high level of energy density (i.e. 93.6 Wh kg?1 at the power density of 1.75 kW kg?1) and excellent cycling stability (92.2% after 5000 cycles). This study demonstrates that the N/C@Ni-Co LDH is a promising candidate electrode material for the fabrication of high energy density supercapacitors.
NSTL
Elsevier