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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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    In situ surface reconstruction on LaCoO3?δ leads to enhanced hydrogen evolution reaction

    Liu D.Chen M.An K.Chen Y....
    7页
    查看更多>>摘要：Perovskite oxides have been considered as ideal electrocatalysts for water electrolysis since they are eco-friendly, abundant, and easy to be fabricated. However, their application in hydrogen evolution reaction (HER) is still limited because of relatively poor efficiency and stability. Herein, we report that a facile fabrication method, pulsed laser deposition, is employed to fabricate nanoscale LaCoO3?δ on nickel foam as an active electrocatalyst for HER. We find that in-situ surface reconstruction takes place in HER cycles, which enhances the HER activity greatly. By depositing additional NiO layer and annealing in H2 atmosphere, the catalytic performance and long-term stability of LaCoO3?δ can be further improved. As a result, the catalyst demonstrates a remarkable HER activity with a low overpotential of 180 mV at 10 mA cm?2 and superb stability up to 50 h in alkaline media. Our work uncovers that the underlying phase transition in an alkaline medium and the interface engineering play critical roles in the improved HER activity of perovskite oxides. This work may provide insightful guidance to engineer perovskite oxides as electrocatalysts in the electrolysis of water.
      原文链接:
    • NSTL
    • Elsevier

    Microstructure evolution and properties of NiTiCrNbTax refractory high-entropy alloy coatings with variable Ta content

    Zhang X.Cui X.Jin G.Ding Q....
    12页
    查看更多>>摘要：In this work, the novel NiTiCrNbTax (x = 0.1, 0.3, 0.5, 1) refractory high-entropy alloy (RHEA) coatings were successfully synthesized on Ti6Al4V by laser cladding technology. The effect of Ta content on microstructure, thermal stability, micro-hardness and corrosion resistance of RHEA coatings was investigated in detail. The results showed that NiTiCrNbTax RHEA coatings were composed of BCC, NiTi2-Laves and Cr2Nb-Laves phases. With Ta content increasing, the formation of BCC phase was promoted while the precipitate of Cr2Nb-Laves phase was affected. The average micro-hardness values of Ta0.1, Ta0.3, Ta0.5 and Ta1.0 RHEA coatings were calculated as ~922.8 HV0.3, ~985.1 HV0.3, ~851.3 HV0.3 and ~825.4 HV0.3, respectively. The decrease of micro-hardness value might be ascribed to the reduction of hard Laves phase. After annealing at 900 °C for 3 h, the phase compositions of all RHEA coatings remained unchanged but the grains of Cr2Nb-Laves phase were refined obviously. Besides, RHEA coatings exhibited excellent corrosion resistance and the minimum corrosion current density was 1.08 × 10?7 A/cm2. Moreover, the secondary passivation phenomenon emerged in Ta0.5 and Ta1.0 coatings, and the passive film mainly consisted of the oxidation state of Ti, Cr, Nb, Ta and the sub-oxide state of Nb, Ta.
      原文链接:
    • NSTL
    • Elsevier

    Microstructure evolution and mechanical properties of directionally solidified large size Ti-47Al-5Nb-0.18C-0.3Si alloy by electromagnetic confinement

    Yue X.Shen J.Xiong Y.Zheng S....
    12页
    查看更多>>摘要：Newly designed Ti-47Al-5Nb-0.18C-0.3Si alloys were directionally solidified by electromagnetic confinement with seed method at the pulling rate of 5–20 μm/s. The macro/microstructure evolution, fracture toughness and high temperature tensile property of the alloy were investigated in detail. The results indicate that the large size single crystals with aligned lamellar microstructure are obtained at the pulling rate of 10 μm/s and 15 μm/s, however, when the pulling rate is lower than 10 μm/s or higher than 15 μm/s, the equiaxed crystals and the divergent columnar crystals are presented instead of the single crystals. Solidification process and macro/microstructure evolution are expressed by schematic, and they display the primary α phase solidification characteristic at the pulling rate of 10–20 μm/s. It is found that the interlamellar spacing gradually decreases with the increase of pulling rate, and the relationship between them can be described as d=14174V?0.83. The single crystal with aligned lamellar microstructure at 10 μm/s possesses the better fracture toughness and high temperature tensile properties. Finally, toughening mechanism and strengthening mechanism are analyzed and discussed.
      原文链接:
    • NSTL
    • Elsevier

    Exploring the underlying causes of optimizing thermal conductivity of copper/diamond composites by interface thickness

    Sang J.Yuan Y.Yang W.Zhu J....
    9页
    查看更多>>摘要：To unravel the underlying causes of the opposite variation tendency in theoretical and experimental thermal conductivity of copper/diamond composites as the increasing thickness of nanoscale interface layer, WC layers with 70–400 nm thickness were prepared by magnetron sputtering W layers on the diamond substrates and following vacuum annealing treatment. The interface structure of the WC coated diamond was studied by TEM, and the density (ρ) of the WC layers was measured by the relative peaking intensity of the coating phase using the X-ray scattering strength method. Nanoindentation and four-point probe experiments were also carried out for indirectly characterizing average phonon velocity (ν) and thermal conductivity (KWC) of the WC layers. Interfacial thermal conductance (ITC) of the composites was calculated by the actual experimental ρ, ν and KWC of the WC nanoscale layers. Meanwhile, corresponding copper/diamond composites were fabricated by pressure-assisted infiltration method. The maximum thermal conductivity (TC) of the composite achieved 943 W·m?1·K?1. The variation trend of the actual TC in the composites was agreed with that of the calculated ones which were calculated by the ITC and differential effective medium (DEM) model. Based on the above quantitative analysis, the thermal boundary conductance of WC/Cu and diamond/WC interface is the main factor that leads to the variation of TC of the composites with the increase of the WC interlayer thickness. Optimizing a higher thermal boundary conductance by regulating the interlayer thickness is a crucial factor for enhancing the TC of the composite.
      原文链接:
    • NSTL
    • Elsevier

    Stimulating photodiode characteristics of hybrid ZnPc-MWCNTs

    Osama R.Al-Kamel A.N.Morsy M.Mahmoud E.A....
    10页
    查看更多>>摘要：The ability to functionalize multi-wall carbon nanotubes (MWCNTs) with organic semiconductors is a promising methodology to promote their use in multiple optoelectronic applications, especially at the visible region of the optical spectra. In this article, we investigate the structural, optical, and electrical properties of chemically synthesized MWCNTs hybridized with zinc phthalocyanine (ZnPc) molecules. Interestingly, the hybrid ZnPc-MWCNTs optical bandgap shifts towards the visible light at 2.6 eV instead of the near-infrared bandgap of the pristine sample at 1.2 eV. Besides, the ZnPc-MWCNTs hybrid exhibits enhanced p-n heterojunction photodiode characteristics that are significantly improved with temperature increase. Moreover, the I-V curves of the hybrid ZnPc-MWCNTs sample under visible illumination conditions express a current intensity three times higher than the pristine MWCNTs sample. This promotes the use of the ZnPc-MWCNTs hybrid in various optoelectronic applications working in the visible region of optical spectra.
      原文链接:
    • NSTL
    • Elsevier

    Nickel-cobalt derived nanowires/nanosheets as electrocatalyst for efficient H2 generation via urea oxidation reaction

    Liu Y.Guan J.Chen W.Wu Y....
    9页
    查看更多>>摘要：Exploring high-efficient catalysts to reduce the voltage of the electrolytic cell is pivotal for large-scale hydrogen production, and using other electrochemical reactions to replace inert oxygen evolution reaction (OER) is also a feasible way. In this paper, a series of Ni[sbnd]Co precursors supported by carbon cloth (CC) were prepared by hydrothermal method and subsequently treated with phosphating and oxidation, respectively. The phosphating products and oxidation products were used for hydrogen evolution reaction (HER) and urea oxidation reaction (UOR), respectively. The materials morphology and electron configuration were also controlled by adjusting relative Ni[sbnd]Co content in the precursors. Furthermore, the effects of different Ni-Co ratios on electrocatalytic activity under the same crystal structure were discussed in detail. Benefited from the optimum electron structure and maximum active sites, Ni2Co1-P/CC displayed the best HER catalytic performance, with an overpotential of 79 mV to reach 10 mA cm?2. On account of the comparatively low theoretical oxidation voltage of urea, NixCo3?x-O/CCs displayed a much lower working potential in urea-containing electrolyte than the urea-free electrolyte. Thereinto, Ni1.5Co1.5-O/CC showed the best UOR catalytic performance, with a potential of 1.362 V at η10 in 1.0 M KOH and 0.33 M urea. With the combination of the above catalysts, it needed only 1.47 V to drive the current density of 10 mA cm?2 in the electrolytic cell for hydrogen production via UOR.
      原文链接:
    • NSTL
    • Elsevier

    Ti-Cr-Mn-Fe-based alloys optimized by orthogonal experiment for 85 MPa hydrogen compression materials

    Peng Z.Li Q.Chen K.Jiang W....
    9页
    查看更多>>摘要：The development of hydrogen storage alloys possessing high plateau pressures for three-stage metal hydride hydrogen compressors (MHHCs), is critically significant for the safe and high-efficiency re-/charging of H2 in hydrogen refueling stations (HRSs). Herein, Ti-Cr-Mn-Fe-based alloys (Ti1.04+xCr2?y-zMnyFez, x = 0.02, 0.04, 0.06, y = 0.2, 0.3, 0.4, z = 0.5, 0.6, 0.7) synthesized by vacuum arc melting, with the single structure of C14 Laves and uniform element distribution, enable the final-stage compression units up to 85 MPa for MHHCs. It is demonstrated that both unit cell volume and maximum hydrogen capacity (Cmax) increase by the rising amount of Ti or decreasing Mn and Fe in the Ti-Cr-Mn-Fe-based alloys, whereas the dissociation pressures and plateau hysteresis (Hf) at 223 K are reduced correspondingly, according to the orthogonal results. Meanwhile, as the over-stoichiometric amount of Ti increases, so does the plateau slope (Sf) of the Ti-Cr-Mn-Fe-based alloys. Under the optimized conditions conducted by the orthogonal results, Ti1.08Cr1.3Mn0.2Fe0.5 exhibits comprehensively considerable hydrogen absorption/desorption properties, rendering it possible to be one of the most promising final-stage compression materials. Notably, the dehydrogenation enthalpy and entropy for Ti1.08Cr1.3Mn0.2Fe0.5 is determined to be 22.3 ± 0.3 kJ/mol and 117.8 ± 1.0 J/(mol K), respectively, with a corresponding hydrogen absorption pressure of 14.00 ± 0.52 MPa at 298 K and a dehydriding pressure of 89.19 ± 3.21 MPa at 363 K. Furthermore, the values of Cmax, Hf,andSf are evaluated as 1.83 ± 0.01 wt%, 0.33 ± 0.01, and 0.72 ± 0.03, respectively, at 223 K.
      原文链接:
    • NSTL
    • Elsevier

    Role of oxygen on the precipitation and deformation behavior of an aged β Ti-15Mo alloy

    Chou K.Marquis E.A.
    12页
    查看更多>>摘要：The mechanical behavior of aged metastable β titanium alloys is directly influenced by the formation and stability of metastable ω and stable α phases during thermomechanical processing. Interstitial oxygen, which is known to cause embrittlement in Ti alloys, affects phase stability in these alloys and also impacts their structural properties. The present study investigated the role of interstitial oxygen on ω and α precipitation in an aged metastable β Ti-15Mo alloy and the subsequent effect of these microstructural changes on the alloy's compressive mechanical properties. High oxygen levels reduced the ω growth rate and induced a shape change for ω precipitates with oxygen partitioning to ω precipitates during ageing. Oxygen-containing specimens displayed higher compressive yield strengths than in oxygen-free specimens during micropillar compression testing. However, in both cases, ω precipitates were ultimately sheared leading to slip band formation and plastic flow localization. Elevated oxygen also refined the α precipitate distribution whether α nucleation happened homogeneously or heterogeneously. The finer α precipitates with oxygen led to increased compressive yield strength during micropillar compression compared to specimens without oxygen. Oxygen plays a key role in the evolution of ω and α precipitate distributions and associated mechanical properties, which is another example of how oxygen may be a useful alloying element in β titanium alloys.
      原文链接:
    • NSTL
    • Elsevier

    Influence of plastic deformation on the corrosion behavior of CrCoFeMnNi high entropy alloy

    Jin J.Zhang M.Liu F.Wang X....
    10页
    查看更多>>摘要：In this research, the influence of plastic deformation on the corrosion behaviors of CrCoFeMnNi high entropy alloy were comprehensively investigated. As the degree of plastic deformation increases, both the acceptor density of the passive film and the thickness of the space charge layer increase, while the resistance of the passive film gradually weakens. The Fe and Cr oxides on the passive films decrease with the increasing plastic deformation degree, resulting in the weaker resistance of the passive film. Numerous dislocations formed after plastic deformation promote the increase of electrochemical dynamics and galvanic corrosion rate. Therefore, severe plastic deformation lowers the corrosion resistance of the alloy.
      原文链接:
    • NSTL
    • Elsevier

    Design of ternary high-entropy aluminum alloys (HEAls)

    Asadikiya M.Zhang Y.Apelian D.Zhong Y....
    11页
    查看更多>>摘要：Two novel aluminum alloys were designed and studied by incorporating concepts of high entropy and conventional aluminum alloys. The alloys: Al–4Zn–4Mg and Al–4.5Zn–4.5Mg (mol.%) have a single-phase FCC matrix with a maximized concentration of the alloying elements. CALculation of PHAse Diagrams (CALPHAD) approach was applied to determine the compositions and the design of heat treatment schedules. Both alloys show high stiffness and high strength after solution treatment and have excellent impact-resistance after artificial aging. The phase stabilities and strengthening mechanisms were investigated using Optical Microscopy (OM), Scanning Transmission Electron Microscopy (STEM), and X-Ray Diffraction (XRD). The results show that the GP zones and T-phase nanoparticles are mainly responsible for the high stiffness-high strength and impact resistance properties.
      原文链接:
    • NSTL
    • Elsevier