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Journal of Alloys and Compounds
Elsevier Science S.A.
Journal of Alloys and Compounds

Elsevier Science S.A.

0925-8388

Journal of Alloys and Compounds/Journal Journal of Alloys and CompoundsSCIISTPEI
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    Particle size dependent microstructure evolution of inert gas atomized nickel base superalloy powders

    Kumar G.S.Sateshwar M.Sharma A.R.Palit M....
    10页
    查看更多>>摘要：? 2022 Elsevier B.V.Powder of an experimental Nickel base superalloy produced through Inert Gas Atomization technique is characterized for its physical properties, chemical composition, morphology, micro-segregation and orientation distribution of grains. The atomized powders exhibits near spherical morphology with average particle size of 61 μm. Micro-chemical analysis reveal, elements like Ti, Mo, Ta and Hf partition at inter-dendritic regions, irrespective of particle size.The extent of micro-segregation however is found to be intimately related to the cooling rate and particle size. The EBSD analysis reveals random texture in the particles with the number of grains per particle decrease with decreasing particle size. The nucleation event is found to be initiated on particle surfaces as evidenced from the dominant presence of the Low Angle Grain Boundaries (LAGBs) near the particle surfaces. The selective growth of favourably oriented nuclei are observed towards the core of the particle and characterized by presence of High Angle Grain Boundaries (HAGBs) in the particle interior. A mechanistic understanding correlating evolution of grain size distribution and micro-segregation with droplet solidification process, has been elucidated through the present study.
      原文链接:
    • NSTL
    • Elsevier

    Willow leaf-shape ReSe2@C as positive electrode material for aluminum-ion batteries

    Zhou Q.Wang D.Ni L.Zhang H....
    8页
    查看更多>>摘要：? 2022 Elsevier B.V.Recently, aluminum-based batteries have received extensive attention from researchers because of their advantages over other metals-based batteries in terms of cost, energy density, and safety performance. Herein, we synthesized willow leaf-shape ReSe2@C as the positive electrode of aluminum batteries. ReSe2, with anisotropic crystal structure, is encapsulated in carbon using weak interlaminar van der Waals force. Its low lattice symmetry increases the ion/electron adsorption sites and reduces the energy barrier for ion intercalation into ReSe2 layers. The electrochemical analysis and X-ray photoelectron spectroscopy of ReSe2@C have ascertained that AlCl4- is intercalated/embedded in host material during charging/discharging. The specific discharge capacity of ReSe2@C remains 88 mA h g?1 after 1000 cycles at the current density of 100 mA g?1, with a high Coulomb efficiency of 98%.
      原文链接:
    • NSTL
    • Elsevier

    Controllable synthesis and phase-dependent electrocatalytic oxygen evolution performance of CoNiFe sulfide nanocubes

    Cheng H.Zhou H.Zhuang Y.Chen B....
    7页
    查看更多>>摘要：? 2022 Elsevier B.V.The electrochemical oxygen evolution reaction (OER) highly depends on the phase structure of catalysts. Herein, the CoNiFe-based sulfides are fabricated by a surface decoration on NiFe Prussian blue analogue, followed by an evaporating sulfurization process. The as-formed metal sulfides have a nanocubic morphology and show a phase-dependent OER activity in alkaline electrolyte. The optimized catalyst possesses a remarkable activity and durability towards OER, featured by a low overpotential of 288 mV at 10 mA cm?2 and a small Tafel slope of 72 mV dec?1. The outstanding OER performance originates from the hierarchically porous architecture and interfacial coupling between CoS2 and (Ni,Fe)S2 phases. Our finding provides a promising strategy to develop advanced low-cost electrocatalysts with intriguing phase structure by producing the heterojunctions via post treatments on PBA such as surface modification and evaporation sulfidization.
      原文链接:
    • NSTL
    • Elsevier

    Energy-efficient synaptic devices based on planar structured h-BN memristor

    Wang Y.Liu H.Liu P.Lu W....
    6页
    查看更多>>摘要：? 2022 Elsevier B.V.Synapses with short-term plasticity (STP) and long-term plasticity (LTP) behaviors are the key factors for the development of complex neuromorphological systems. Two dimensional (2D) materials have shown great potential at synaptic devices because of their unique properties. In this work, synaptic devices with a planar structure using insulated 2D hexagonal boron nitride (h-BN) as resistance switching (RS) medium were studied for the first time. Different from vertical h-BN synaptic devices, planar h-BN synaptic devices support in-plane transport of metal ions through nanoscale channels, which weakens the influence of material defects, morphology, thickness and uniformity on device performance. The Ag/h-BN/Ag planar structured synaptic devices exhibited low switching voltage (< 1 V), high On/Off ratio (> 108), wide range of tunable operation current (0.1 nA–1 mA), and coexistence of volatile (SET power ≤ 50 nW) and non-volatile (SET power ≥ 700 nW) RS characteristic. In addition, the multi-stage resistance states could be modulated by setting different SET power. The device efficiently mimicked the STP and LTP synaptic functions, and the energy consumption per synaptic event was as low as 170 fJ/spike for STP and 540 fJ/spike for LTP, respectively. In addition, the multi-memory states of synaptic devices could be obtained by adjusting the postsynaptic current (PSC).
      原文链接:
    • NSTL
    • Elsevier

    Novel transparent Tb3+-activated Na2GdF7 glass ceramics for low-lying state thermal coupling principle

    Hu F.Hailin G.Ashraf G.A.Tao X....
    7页
    查看更多>>摘要：? 2022 Elsevier B.V.Oxy-fluoride glass ceramics (GC), which are composed of glass phase and equally distributed fluoride nano-crystals, are regarded as promising host materials employed to optical thermometer. Herein, novel Na2GdF7:xTb3+ (x = 0.02, 0.03, 0.04, 0.05, and 0.06) GC with high transparency were well fabricated and applied to low-lying state thermal coupling principle. The structural, micro-topography and fluorescence spectra properties of these samples were completely researched via XRD, TEM, HRTEM, SAED and photoluminescence. When excited by 378 nm laser, the luminescence of Na2GdF7:0.3Tb3+ GC was increased 1.5 times compared with precursor glass. More importantly, the Na2GdF7:0.3Tb3+ GC sample (λex = 541.8 nm) was devoted to low-lying state thermal coupling principle. The strategy endows excellent relative sensitivity and superior temperature resolution which are 2.33% K?1 at 310 K and 0.06 K at 670 K, respectively. These findings suggest potential optical materials and a strategy for optical fiber temperature sensing.
      原文链接:
    • NSTL
    • Elsevier

    High power laser powder bed fusion of AlSi10Mg alloy: Effect of laser beam mode

    Deng J.Zeng X.Liu M.Wei K....
    13页
    查看更多>>摘要：? 2022 Elsevier B.V.High power laser powder bed fusion (HP-LPBF) is a burgeoning additive manufacturing technology for the high-efficiency and high-accuracy build of metallic parts. However, studies about the effect of laser beam mode on build quality is still insufficient. In this paper, both a 2 kW multi-mode fiber laser and a 2 kW Gaussian mode fiber laser are used for the HP-LPBF of AlSi10Mg alloy. Firstly, the relative density (RD) of the HP-LPBF samples has been studied for parameter optimization. The RD of the samples built with the multi-mode laser beam (hereafter called as Multi-mode sample) first increases and then remains stable with the increase of laser energy density Ev. When Ev is no less than 50 J/mm3, the RD of the Multi-mode sample is higher than 99.5%. In contrast, the RD of the samples built with the Gaussian mode laser beam (hereafter called as Gaussian sample) first increases and then decreases with the increase of Ev, and the highest RD is just 95.87 ± 0.2% at the Ev of 50 J/mm3. Based on this, the Multi-mode sample and Gaussian sample built with the same parameters (Ev=50 J/mm3) are chosen as the typical contrast samples for further studies of surface quality, microstructure and tensile property. The results show that the typical Multi-mode sample presents a flatter surface and a lower surface roughness compared with the Gaussian sample. The phase composition of both the two kinds of samples consists of α-Al matrix and eutectic Si. However, the solidification microstructure varies with laser beam mode. The Multi-mode sample presents a columnar solidification microstructure with a strong< 100 > texture along the build direction. In contrast, the solidification microstructure of the Gaussian sample is a mixture of equiaxed grains and short columnar grains. The crystallographic orientations of the two kinds of grains are multifarious, leading to a much weaker texture. The tensile strengths and elongation of the Multi-mode sample are significantly better than those of the Gaussian sample. The effect mechanisms of the laser beam mode on relative density, surface quality, microstructure and tensile property have also been revealed.
      原文链接:
    • NSTL
    • Elsevier

    Magnetic structure, magneto-caloric properties and magnetic critical behaviours of LaMn2Ge2 compounds

    Wang X.X.Wang W.Q.Hao H.Y.Su F....
    7页
    查看更多>>摘要：? 2022 Elsevier B.V.The structural and magnetic properties of LaMn2Ge2 compound in both the as-cast bulk and melt-spun ribbon forms have been investigated by a comprehensive set of x-ray/neutron powder diffraction, magnetic and heat capacity measurements as well as corresponding sets of data analyses. Our neutron diffraction study reveals that with decreasing temperature the magnetic state of bulk LaMn2Ge2 changes first from paramagnetic to incommensurate antiferromagnetism AFfs at TN ~ 430 K, and then gives way to incommensurate canted ferromagnetism Fmi below TC ～ 320 K. No noticeable magnetoelastic effect was detected in the temperature dependence of lattice parameters derived from the refinement of the neutron diffraction patterns over the temperature range ~ 5–460 K. Detailed analyses of the magnetic data indicate that the magnetic phase transition around the ferromagnetic transition (TC ～ 320 K) is second order. Under field changes of 2 T and 5 T, the maximum values of magnetic entropy change around the ferromagnetic transition respectively reach -ΔSmax = 1.65 J/kg K and -ΔSmax = 3.26 J/kg K for the bulk sample, compared with -ΔSmax = 1.21 J/kg K and -ΔSmax = 2.60 J/kg K, for the ribbon sample. The magnetic phase transition around TC has been investigated by Kouvel-Fisher analysis and the Modified Arrott Plot method with the critical exponent values indicating that the magnetic interactions in LaMn2Ge2 are long range. Moreover, it was found that the field- and temperature- magnetisation data around TC collapse onto two curves obeying the single scaling equation M(H,ε) = εβf ± (H/εβ+γ) for both the bulk and ribbon samples. With a field change of ΔB = 5 T and ΔB = 8 T, the relative cooling power for bulk sample around 320 K is derived to be RCP ~ 115 J/kg and RCP ~ 199 J/kg, respectively. These findings indicate that LaMn2Ge2 could be a promising candidate for magnetic refrigeration applications in the room temperature region.
      原文链接:
    • NSTL
    • Elsevier

    Analysis of anisotropy mechanism in relation with slip activity in near α titanium alloy pipe after Pilger cold rolling

    He S.Zeng W.Xu J.Zhou D....
    17页
    查看更多>>摘要：? 2022 Elsevier B.V.Understanding of anisotropy mechanism for Pilger rolling Ti80 (Ti-6Al-3 Nb-2Zr-1Mo) alloy pipe is of great significance to improve its service performance. In this work, the strength, plasticity and fracture mode of Ti80 alloy pipe with rolling texture in three different directions (RD, TD and 45°) were comparatively investigated. Firstly, the tensile strength is in the descending order of TD, RD and 45°, and plasticity shows the opposite trend. According to the statistics of a large number of deformed grains, the underlying mechanism of anisotropy was revealed by analyzing the slip activation, slip transfer, damage and fracture for three different loading directions. The results show that prismatic<a> slip is the dominant deformation mechanism in RD, and the basal<a> slip is mostly activated in TD. In 45°, the number of activated prismatic<a> slip and basal<a> slip is almost the same. Meanwhile, the pyramidal<a> slip plays an important role in accommodating the plastic deformation. A method for predicting the yield strength was established based on the critical resolved shear stress (CRSS) of basal<a> slip, prismatic<a> slip and pyramidal<a> slip, accompanying by different SFs distributions of activated slip systems. Subsequently, slip transfer, which can relieve the incompatible deformation, occurred between adjacent α grains when the slip transfer factor (m) and Schmidt factor (SF) are at a high value. Slip transfer was prone to occurring between the same slip systems, such as between prismatic<a> slip or basal<a> slip. However, it is discovered that the slip transfer between prismatic<a> slip and basal<a> slip is also likely to occur, when the adjacent α grains maintain 90° variant relationship. The slip transfer between 90° variants in 45° have higher probability than that in RD and TD due to high SFs of activated basal<a> slip and prism<a> slip, resulting better plasticity. Lastly, the micro-defects are uniformly distributed and the fracture mode is microvoids coalescence in RD. More basal<a> slip induces the cleavage cracks and cause the shear fracture in 45°. In TD, a mixed fracture mode of microvoids coalescence and cleavage is presented due to the heterogeneous deformation.
      原文链接:
    • NSTL
    • Elsevier

    One-step microwave synthesis of in situ grown NiTe nanosheets for solid-state asymmetric supercapacitors and oxygen evolution reaction

    Zhang T.Li J.Bi R.Song J....
    10页
    查看更多>>摘要：? 2022 Elsevier B.V.In this work, self-supported NiTe nanosheets were prepared via one-step microwave method. XRD and XPS spectroscopy showed the successful synthesis of NiTe material in the hexagonal crystal system. SEM and EDS were used to identify the microscopic morphology and composition of NiTe on nickel foam (NF). The electrode demonstrated specific capacitance (Cs) of 808.9 F g?1 and ultra-long cycle life of 60,000 cycles. In addition, a solid-state asymmetric supercapacitor consisted of NiTe@NF electrode as cathode material and demonstrated the largest energy density and power density of 94.4 μWh cm?2 and 7801.8 μW cm?2, respectively, and the specific capacitance remained 83.3% after 20,000 cycles. Moreover, the as-obtained NiTe@NF catalyst also displayed an excellent catalytic activity for oxygen evolution reaction (OER), which achieved an ultra-low overpotential of 199.5 mV at 10 mA cm?2.
      原文链接:
    • NSTL
    • Elsevier

    Titanium and fluorine co-modification strengthens high-voltage electrochemical performance of LiCoO2

    Shi B.Hu S.Feng J.Zhou Y....
    11页
    查看更多>>摘要：? 2022 Elsevier B.V.The cathode material for lithium-ion batteries, LiCoO2 (LCO), is suffered from the structural damage and rapid performance degradation at high voltage. In this article, a hydrolysis-calcination method was explored to modify the single-crystal LCO particles with Ti&F co-modification, aiming at strengthening the structural stability through decreasing the energy barrier of lithium ion diffusion. Evaluated at high voltage (3.0–4.55 V), the optimal sample LCO-TF2 has the initial discharge capacity of 199.3 mAh g?1 and capacity retention rate of 75% after 100 cycles at 1 C and 45 °C, significantly higher than that of the pristine sample (192.8 mAh g?1 and 35%). Characterized by XRD, TEM, XPS, etc., it is illustrated that the Ti&F co-modified sample LCO-TF2 has the rock-salt phase on its surface besides the layered structure inside. GITT results indicate that Li+ diffusion coefficients of LCO-TF2 are more than twice times of those of LCO under the voltage range of 4.0–4.55 V. The in-situ XRD tests reflect that during the charge-discharge cycle the crystal structure variation of LCO-TF2 is suppressed during Li+ extraction and insertion. Further, DFT calculations disclose that with the co-modification of Ti and F the surface film of LiCoO2 possesses lower energy barrier of Li-ion diffusion. These results would provide useful guidance on improving electrochemical performance of LiCoO2 at high cut-off voltage.
      原文链接:
    • NSTL
    • Elsevier