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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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    Correlation of crystal orientation, crystal morphology and mechanical properties of directionally solidified Mg-xGd alloys

    Geng C.G.Fang D.R.Lin X.P.Lian Y.Q....
    9页
    查看更多>>摘要：? 2022 Elsevier B.V.The Mg-xGd (x = 4–16, wt%) alloys with columnar crystals were prepared by directional solidification, and the effect of Gd content on the crystal orientation, microstructure, and tensile properties at room temperature were studied. The microstructure of the Mg-4Gd alloy is single α-Mg solid solution, and the microstructure of the Mg-6Gd alloy is composed of α-Mg and Mg24Gd distributed along the longitudinal grain boundaries of columnar crystals, while the microstructure of the Mg-(8?16)Gd alloys consists of α-Mg and lamellar eutectic phase. The Mg-4Gd alloy with growth orientation concentrated in< 112(_)0 > (hard orientation) has high yield strength (186 MPa) and moderate elongation (12 %), because {101(_)1} compression twinning are activated to coordinate strain. However, the Mg-6Gd alloy with growth orientation concentrated in<1(_)21(_)2 > (soft orientation) has excellent elongation (38 %), as a result of activated {101(_)2} tension twinning. When the Gd content exceeds 12 %, plenty of eutectic phases will cause low strength and poor plasticity of the Mg-Gd alloys.
      原文链接:
    • NSTL
    • Elsevier

    Toward tunable microstructure and mechanical properties in additively manufactured CoCrFeMnNi high entropy alloy

    Li H.Fu W.Chen T.Huang Y....
    9页
    查看更多>>摘要：? 2022 Elsevier B.V.Tailoring microstructure and mechanical properties of structural materials to meet application requirements is a long-standing challenge in materials science. Here we have studied the effects of laser energy density (LED) on the microstructure and mechanical properties of single-track CoCrFeMnNi high entropy alloy (HEA) samples fabricated by laser directed energy deposition (LDED). The results indicate that the molten pool size of the single-track HEA samples gradually increases with increasing LED. All of the samples possess a single face-centered cubic (FCC) solid solution structure. The microstructures of the single-track HEA samples are mainly composed of columnar and equiaxed grains, and as the LED increases, their grain size increases while the micro-hardness decreases. Additionally, the relationship among the processing parameters, cooling rate and grain size was investigated via combining the numerical simulation and experimental observations. This work provides mechanistic insights into establishing the processing-structure-property relationships in the additively manufactured HEAs and contributes to achieve LDED of tunable HEA parts with desired microstructure and mechanical performance.
      原文链接:
    • NSTL
    • Elsevier

    Heterostructured Mn clusters/N-doped carbon foams enhancing the polysulfides immobilization and catalytic conversion

    Huang Z.Wang H.Wang X.Wang R....
    8页
    查看更多>>摘要：? 2022 Elsevier B.V.Lithium-sulfur batteries (LSBs) are favored for their high theoretical energy capacity and low production costs. However, their wide applications are currently challenged by the polysulfide shuttle effect and slow redox reactions resulting from the poor polysulfides immobilization-conversion kinetics in the sulfur cathodes. In this work, the heterostructure Mn Clusters/N-doped Carbon Foams composite catalyst was prepared by using the molten NaCl as template. The optimal electrode sample exhibited the improved chemisorption and catalytic conversion of the polysulfides. Sequentially, the polysulfide shuttle effect and volume expansion during the reaction were effectively alleviated. As a result, the assembled sulfur electrode achieved a discharge specific capacity of 505.8 mA h g?1 after 300 cycles at 1 C with an average capacity decay rate of only 0.065 % per cycle.
      原文链接:
    • NSTL

    Experimental investigation and thermodynamic description of the Co–Nb–Ti system

    Bai X.Guo C.Li C.Du Z....
    18页
    查看更多>>摘要：? 2022 Elsevier B.V.The solidification microstructures of as-cast alloys and the equilibria microstructure of annealed alloys at 1273 K in the Co–Nb–Ti system were determined by scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS) and X-ray diffraction (XRD), and the liquidus surface projection and partial isothermal section at 1273 K were constructed. Nine primary solidification regions, bcc(Nb,Ti), fcc(Co), Co3Ti, CoTi, CoTi2, λ1, λ2, λ3, and μ and five ternary invariant reactions, liq. → λ1 + λ2 + μ, liq. → CoTi + λ2 + μ, liq. → bcc(Nb,Ti) + CoTi + μ, liq. + fcc(Co) + λ3 → Co3Ti, and liq. + CoTi → bcc(Nb,Ti) + CoTi2 were experimentally determined or deduced in the liquidus surface projection. Three three-phase regions, CoTi + λ2 + μ, bcc(Nb,Ti) + CoTi + μ, and bcc(Nb,Ti) + CoTi + CoTi2 and six two-phase regions, Co3Ti + λ3, λ2 + μ, CoTi + λ2, CoTi + μ, bcc(Nb,Ti) + μ, and bcc(Nb,Ti) + CoTi at 1273 K were experimentally determined. The continuous compound λ2 with a C15 structure from the Co–Nb side to Co–Ti side was formed at 1273 K. The solubilities of Ti in μ and Nb in CoTi were determined to be ~11.1 at% and ~18.4 at% at 1273 K, respectively. And no new phases were found. According to the available experimental data from the present work and literatures, the Co–Nb–Ti system was optimized by CALPHAD (CALculatiuon of PHAse Diagram) method. Four solution phases (liquid, bcc, fcc, and hcp) were described using the substitutional solution model. A two-sublattice model (Co,Nb,Ti)2(Co,Nb,Ti)1 was used to described three compounds λ1, λ2, and λ3 according to their crystal structures and homogeneity ranges. Co7Nb2 and CoTi2 were treated as Co7(Nb,Ti)2 and Co(Nb,Ti)2 by a two-sublattice model, respectively. μ was treated as (Co,Nb,Ti)1(Nb,Ti)4(Co,Nb,Ti)2(Co,Nb,Ti)6 by a four-sublattice model. Co3Ti with L12 structure and CoTi with B2 structure were treated as the ordered phases of fcc and bcc solutions using the thermodynamic models (Co,Nb,Ti)0.75(Co,Nb,Ti)0.25Va1 and (Co,Nb,Ti,Va)0.5(Co,Nb,Ti,Va)0.5Va3, respectively. A set of self-consistent thermodynamic parameters of the Co–Nb–Ti system was obtained.
      原文链接:
    • NSTL
    • Elsevier

    Li-Indium alloy anode for high-performance Li-metal batteries

    Jing W.Zou K.Dai X.Sun J....
    9页
    查看更多>>摘要：? 2022Lithium metal has been considered one of the most ideal anode materials for batteries due to its ultrahigh theoretical capacity and energy density. However, the unstable SEI layer and the growth of Li dendrites cause poor cycling performance and even safety hazards, which also severely restrict the commercial application of Li metal batteries. In this paper, a Li-In alloy anode was designed and prepared by mechanical rolling of both Li and In pure metal foils together. Three-dimensional Li-In alloy network structures are formed by mechanical alloying during rolling, and the 3D Li-In alloy structure not only possesses strong lithium affinity but also possesses more interface between the Li matrix and the second phase formed in mechanical alloying, which can promote rapid diffusion at the interface and uniform deposition of lithium ions. As a result, the Li-In electrode shows an extremely low overpotential of approximately 35 mV at a high current density of 5 mA cm?2 during the lithium plating/stripping experiment. In addition, the battery revealed a higher discharge capacity of 295 mAh/g at 0.05 C and capacity retention of 80 % after 150 cycles when the Li-In alloy was used as the anode electrode in a cell with Li1.2Ni0.2Mn0.6O2 as the cathode. The Li-In alloy can also be used as anode of Li-S battery, the result showed that the capacity decay rate was reduced from 0.22 % to 0.1 % after 200 cycles without any decoration treatment of S cathode except conductive carbon. This work verified that indium in the Li-In alloy can effectively protect the lithium anode and provides an idea for the practical application of lithium metal batteries.
      原文链接:
    • NSTL
    • Elsevier

    A comparative study of microstructure and mechanical properties of ODS CrFeNi-based medium- and high-entropy alloys

    Peng S.Lu Z.Li X.Yu L....
    13页
    查看更多>>摘要：? 2022 Elsevier B.V.Medium- and high-entropy alloys (MEAs and HEAs) intrigue extensive interest of worldwide scholars for their unique properties. In this paper, oxide dispersion strengthened (ODS) CrFeNi-based MEA and HEAs with 1 wt% Y2O3 and 1 wt% Zr addition were fabricated by mechanical alloying (MA) and spark plasma sintering (SPS). The differences between ODS-MEA and ODS-HEA in microstructure (especially nanoscale oxides) and mechanical properties were characterized and compared by XRD, XPS, BSE, HRTEM, STEM, Vicker's hardness and compression test. MAed ODS-CrFeNi MEA, ODS-CoCrFeNi and ODS-CoCrFeNiMn HEA powders are of single face-centered cubic (FCC) crystal structure. After sintering, all three alloys consist of FCC matrix, body-centered cubic (BCC) structured Cr-rich phases, few Cr/Mn-rich oxides and high-density nanoscale oxides. Nanoscale oxides formed in the three alloys are all identified as Y4Zr3O12. In ODS-CrFeNi, the average size of oxides is 10 nm, and the number density in the BCC phase (3.2 ×1022/m3) is higher than that in FCC matrix (3.9 ×1021/m3). In ODS-CoCrFeNi and ODS-CoCrFeNiMn, the average size and number density of oxides increase to 19 nm, 20 nm and decrease to 2.3 × 1021/m3, 1.9 × 1021/m3, respectively. The amount of BCC phase decreases significantly in ODS-CoCrFeNi and ODS-CoCrFeNiMn HEAs compared with ODS-CrFeNi MEA. With the increasing principal element number, high entropy effect promotes more Y2O3 and Zr dissolve in the matrix during MA, but higher Y/Zr solubility and less precipitation of nanoscale oxides Y4Zr3O12 in the alloys during SPS/annealing. ODS-CrFeNi MEA exhibits the highest hardness of 475 HV and the highest compressive yield strength of 1531 MPa.
      原文链接:
    • NSTL
    • Elsevier

    Investigation and characterization of an Al-Mg-Zr-Sc alloy with reduced Sc content for laser powder bed fusion

    Casati R.Cuccaro F.Vedani M.Andrianopoli C....
    13页
    查看更多>>摘要：? 2022Only few high strength Al alloys are processable by Laser Powder Bed Fusion due to the occurrence of hot cracks during solidification. In recent years, the addition of Zr and Sc in Al-Mg alloys revealed an effective solutions to suppress solidification cracking and improve strength. Nevertheless, since Sc is classified as a critical raw material by European Commission due to its high cost and supply risk, its content should be desiderably reduced. It is therefore necessary to focus on novel Al alloys featuring both enhanced processability and low amount of Sc. In this study, we investigated the microstructure and mechanical behavior of an Al-5.2Mg-0.8Zr-0.3Sc alloy, commercially available as m4p? StrengthAl, produced by Laser Powder Bed Fusion. Simulations of equilibrium phase diagrams and Scheil solidification curves showed the precipitation of primary Al3Zr and Al3(Sc,Zr) in the liquid phase on cooling. These particles revealed able to act as nuclei for heterogeneous nucleation of grains, giving rise to a fine equiaxed structure which is able to suppress hot cracking and increase the processability of the Al-Mg-Zr-Sc alloy. Despite the reduced Sc content, the formation of secondary Al3(Sc,Zr) nano-phases during the annealing treatment led to a sharp increase of micro-hardness values, whereas a stress relief effect was monitored by residual stress measurements during aging. Both as-built and aged alloys show a bimodal grain size distribution and a similar crystallographic texture. Yield strength and ultimate tensile strength of 460 MPa and 485 MPa, respectively, were recorded in samples aged at 350 °C for 24 h and at 375 °C for 8 h.
      原文链接:
    • NSTL
    • Elsevier

    Lithium silicates nanodots-decorated SiOx-C/graphene anode material with enhanced rate performance for lithium ion batteries

    Li Z.Zhao H.Tao X.Yang Y....
    8页
    查看更多>>摘要：? 2022 Elsevier B.V.Silicon suboxide (SiOx, 0 <x < 2) is regarded as one of the most prospective anode materials for high-energy-density lithium-ion battery. However, its large-scale application is impeded due to the sluggish electrode reaction kinetics and fast capacity degradation arising from its low conductivity and severe structural degradation. Herein, we reported a lithium silicate (LS) nanodots decorated SiOx-C/graphene material prepared by a facile sol-gel approach with subsequent heat-treatment. The highly-dispersed LS nanodots and graphene sheets provide the fast Li-ion and electron transport for SiOx electrode and therefore enhancing the electrode reaction kinetics of SiOx-C@LS/graphene (SCL-G) electrode. Meanwhile, the highly-conductive network homogenizes the local current density and electrode reactions, which renders homogeneous volume variation and mitigates structural stress of SiOx, resulting in excellent structural durability during repeated cycles. Owing to the synergistic effects, the SCL-G electrode delivered a reversible capacity of 400 mAh g?1 at 0.5 A g?1 without obvious capacity degradation for 200 cycles.
      原文链接:
    • NSTL
    • Elsevier

    Hydrophobic and corrosion-resistant composite (BiVO4/TiO2) hot-dip zinc coating with enhanced self-cleaning ability

    Deepa M.J.Arunima S.R.Shibli S.M.A.
    20页
    查看更多>>摘要：? 2022 Elsevier B.V.The modification of zinc coating through the integration of BiVO4/TiO2 composite is an effective strategy to improve the hydrophobicity, corrosion resistance, and self-cleaning performance along with the photocatalytic performance of the coating. The incorporation of the optimum composition of BiVO4/TiO2 composite facilitates the formation of sharp protrusions, which can enhance and retain air pockets on the surface. Thereby, the real contact between corrosive electrolyte and coating can be significantly suppressed. Thus, the coating becomes hydrophobic in nature with a water contact angle of 120.2° and exhibits good self-cleaning ability. High charge transfer resistance (248.47 Ω cm2) and high inhibition efficiency (91.68%) of the Zn-0.2BVT-1 coating reveal the excellent corrosion resistance characteristics of the coating. The developed hydrophobic coating exhibits excellent chemical stability and durability under both acidic and alkaline environments. Also, the developed coating retains its hydrophobic nature after 21 days of immersion in NaCl solution. A plausible mechanism for the corrosion-resistant characteristics of the coating is proposed based on the electrochemical analysis results. The electrochemical evaluations of the coating confirm that the developed hydrophobic coating, even after 21 days of immersion in NaCl solution, possesses excellent corrosion resistance, durability, chemical stability, and long-term stability to find wide application in marine and industrial fields.
      原文链接:
    • NSTL
    • Elsevier

    Governing mechanism of ion transport in lithium-iron-phosphate glasses

    Baek C.G.Yang Y.S.Rim Y.H.
    10页
    查看更多>>摘要：? 2022 Elsevier B.V.We show a fundamental relationship between network structural attributes and ionic transport of lithium iron phosphate glasses xLi2O–2Fe2O3–3 P2O5 (xLFPO; x = 0.375, 0.75, 1.5, 3.0) used for a cathode in lithium-ion batteries. The glass samples have been synthesized using a solid-state reaction method. We have investigated the electrical characteristics of the glass by combinational measurements of electrical impedance in the frequency 100 Hz – 30 MHz and temperature from ambient to 240 °C, differential thermal analysis, X-ray diffraction pattern, and Raman spectroscopy. The ionic hopping and relaxation processes in xLFPO glasses are analyzed by using Cole-Cole, power law, and modulus representations. We reveal that the exponential increase in dc conductivity with increasing Li2O in xLFPO glasses is caused by the combination of an increase in non-bridging oxygen sites and a change in the bonding forces of iron valence surrounding the iron phosphate clusters inside the network. The power law conductivity, which is driven by the fractional Rayleigh equation, exhibits that the rate of increase in dc ionic conductivity is the same as the rate of increasing numbers of the ionic charge carriers. Raman spectra show that the increase of depolymerization of the iron phosphate network with the addition of Li2O content is due to the conversion of Q2 to Q1 and Q0 species.
      原文链接:
    • NSTL
    • Elsevier