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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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    Preparation of CeVO4 with VO2 as precursor performing high selectivity and sensitivity to ammonia

    Liu Y.Zhang M.Yang L.Wu Z....
    9页
    查看更多>>摘要:? 2022 Elsevier B.V.In this study, nano rod-like pure CeVO4 and composite CeVO4 are prepared from VO2 as a precursor, adjusting the doping ratio of Ce. XPS results show that the V atoms on the surface of CeVO4 are in the form of the V5+and V3+. V3+ acts as the hanging key on the CeVO4 surface and is used as an active site, conducive to the subsequent adsorption of ammonia and redox reactions. Thus, the free electrons absorbed by O2- return to the surface of CeVO4 and improve its ammonia adsorption sensitivity. The prepared CeVO4 ammonia sensor shows a high response (77,825%) and a faster recovery time (~2 s) at room temperature. To explore the effect of water molecules on the ammonia sensitivity of the sensor. Sensors are placed in salt solutions with different humidity. Results reveal a small resistance change in samples at low humidity, indicating that the ammonia gas could be monitored in real-time under low humidity conditions.

    Understanding on processing temperature-metallographic microstructure-tensile property relationships of third-generation nickel-based superalloy WZ-A3 prepared by hot isostatic pressing

    Teng Q.Xie Y.Sun S.Xue P....
    12页
    查看更多>>摘要:? 2022 Elsevier B.V.A third-generation powder metallurgy nickel-based superalloy (WZ-A3) was prepared by hot isostatic pressing (HIP) at 1100 °C, 1150 °C, 1200 °C, and 1250 °C, respectively. The characteristics of grains, precipitates, and elemental distribution revealed its microstructural development. The samples prepared at a sub-solvus temperature (1100 °C) consisted of fine recrystallized grains and dendritic structures. However, the microstructure became a completely recrystallized structure when the HIP temperature reached or exceeded 1150 °C. The average grain size increased from 4.0 μm (1100 °C) to 53.1 μm (1250 °C) due to the promoted recrystallization and atom diffusion rate. Prior particle boundaries (PPBs) with continuously distributed precipitates were identified as a mixture of (Nb, Ti)C carbides and Hf0.5Zr0.5O2 oxides. By increasing the HIP temperature from 1100 °C to 1200 °C, the PPBs were reduced but not eliminated. As a result, samples prepared at 1200 °C experienced interparticle debonding with relatively high strengths, and the ultimate tensile strength values were 1388.7 MPa and 1228.3 MPa at room temperature (RT) and 700 °C, respectively. When the HIP temperature was 1250 °C, the presence of coarse grains, large carbides, as well as eutectic structures formed at the junction of grain boundaries caused dramatic drops of tensile strengths and brittle fractures. These results emphasized the importance of parameter optimization for controlling the microstructure and mechanical properties during the HIPing process.

    Semi-sacrificial template growth of FeS/Fe2O3 heterogeneous nanosheets on iron foam for efficient oxygen evolution reaction

    Guo W.H.Zhang Q.Fu H.C.Yang Y.X....
    8页
    查看更多>>摘要:? 2022 Elsevier B.V.The efficiency of water electrolysis is greatly hindered by complex electron-proton transfer process of oxygen evolution reaction (OER). Exploiting cost-efficient OER electrocatalytic materials to improve the performance of overall water splitting is necessary. Partial chemical etching of iron foam (IF) with glacial acetic acid, using IF as the metal source and substrate, to form vertically aligned FeS/Fe2O3 heterogeneous nanosheets on the IF (FeS/Fe2O3/IF) can obtain a hierarchical electrode to meet the above requirements. The nanosheets with heterogeneous interfaces in situ grown on IF can adjust electronic structure and expose more active sites, resulting in great improvement of catalytic activity and stability. FeS/Fe2O3/IF requires a small overpotential of 266.5 mV to attain 10 mA cm?2 and its Tafel slope is 51.17 mV dec?1. It is worth noting that FeS/Fe2O3/IF can work continuously for 50 h at high current density, which proves the strong stability during the OER process. The FeS/Fe2O3/IF has high electrocatalytic activity and stability, and can be used as a good candidate material for electrocatalytic OER in industrial manufacture.

    Fabrication of a Z-scheme CeO2/Bi2O4 heterojunction photocatalyst with superior visible-light responsive photocatalytic performance

    Wu D.Zhang X.Liu S.Ren Z....
    13页
    查看更多>>摘要:? 2022 Elsevier B.V.In this study, a CeO2/Bi2O4 Z-scheme heterojunction was prepared by using a facile hydrothermal method. After 40 min of visible-light irradiation, this composite photocatalyst displayed superior photocatalytic activity for removing levofloxacin and methyl orange than pure CeO2 and Bi2O4, achieving the degradation efficiencies of 88.75% and 90.3%, respectively. According to the results of transient photocurrent response, electrochemical impedance spectroscopy, and photoluminescence, CeO2/Bi2O4 heterojunction photocatalyst exhibited efficient photoinduced charges separation. The enhanced photocatalytic performance was due to synergy between efficient separation of photogenerated carriers and increased solar absorption. A Z-scheme heterojunction between CeO2 and Bi2O4 was formed, which was contributed by the well-matched band structure, facilitating the fast transfer and separation of carriers. The active species, including h+, O2·–, and ·OH, play key roles in the photodegradation reactions, demonstrated by electron spin resonance spectroscopy. High-performance liquid chromatography-mass spectrometry was used to identify the probable degradation path of levofloxacin. This work will benefit the design of efficient Z-scheme heterojunction photocatalysts for environmental remediation.

    Hydrogen sorption kinetics and suppression of NH3 emission of LiH-sandwiched LiNH2-LiH-TiF4-MWCNTs pellets upon cycling

    Sitthiwet C.Plerdsranoy P.Utke R.Utke O....
    10页
    查看更多>>摘要:? 2022 Elsevier B.V.NH3 emission during decomposition of LiNH2-LiH composite reduces hydrogen storage capacity and poisons fuel cell catalysts. The idea of sandwiching LiNH2-LiH pellet with LiH layers (10–30 wt%), reacting with NH3 and transforming into H2 is proposed. The LiH-sandwiched LiNH2-LiH pellets show no sign of NH3 release with the hydrogen capacitates of 3.5–4.0 wt% H2 during the 1st cycle. Upon cycling (the 2nd-6th cycles), decomposition of LiH-sandwiched LiNH2-LiH pellet with the low amount of LiH layer (10 wt%) shows NH3 signal, while that with 30 wt% LiH layers liberates only hydrogen with the storage capacities of 2.3–2.6 wt% H2. Effective dehydrogenation and reversibility of the 30 wt% LiH-sandwiched LiNH2-LiH pellet are explained by not only sufficient content and mechanical stability of LiH layers but also the formation of the new active phases (LiH1?xFx and Li2NH1?yFy).

    Effect of copper sulfide nanosphere shell on microstructure and microwave absorption properties of cobalt ferrite/carbon nanotube composites

    Wang X.Wei S.Yuan Y.Li R....
    11页
    查看更多>>摘要:? 2022Copper sulfide/cobalt ferrite/multi-walled carbon nanotube (CuS/CoFe2O4/MWCNT) microwave absorbing composites were prepared using a one-step hydrothermal method. The MWCNTs serve as skeletons with small CoFe2O4 spheres and CuS nanoparticles attached to the surface, developing a tube-sphere microstructure. We observed that CoFe2O4 connects MWCNTs and CuS by forming the C-O and S-O covalent bonds, respectively. CuS plays an important role in the adjustment of electromagnetic parameters, i.e., increasing the electromagnetic wave attenuation capacity and decreasing the characteristic impedance. The optimized composite exhibits good microwave absorption properties with a maximum microwave absorption bandwidth of 5.26 GHz at the matching thickness of 1.77 mm. In particular, the minimum reflection loss of the composite can reach ? 58.74 dB at 17.52 GHz with the matching thickness of 4.64 mm, showing a great application prospect in the field of high-frequency electromagnetic wave absorption, e.g., in the Ku band range. The theoretical calculations demonstrate that the electronic structure of the material has changed in the presence of CuS. The energy barrier for electron transfer is reduced, promoting the formation of a specific charge transfer channel, which strengthens the microwave absorption properties of the composites.

    Improving the glass forming ability and plasticity of ZrCuNiAlTi metallic glass by substituting Zr with Sc

    Cheng S.Liu X.Tian J.Ma J....
    9页
    查看更多>>摘要:? 2022 Elsevier B.V.The present study reports the effect of substituting Zr with Sc on the glass forming ability (GFA) and mechanical properties of ZrCuNiAlTi bulk metallic glass (BMG). Results showed that Zr57-xCu20Ni8Al10Ti5Scx (x = 0, 1, 2, 3, 4 at%) BMGs had the best GFA at x = 2, and the critical size was 10 mm, which correlated well with the GFA indicator (Trg and γ). The large atomic radius of Sc and small Gibbs free energy difference between the supercooled liquid and crystalline solid (ΔGl-c) caused significant atomic size mismatch and inhibited crystallization during cooling, ultimately improving GFA. Compression test results indicated that the plasticity of the Zr55Cu20Ni8Al10Ti5Sc2 BMG increased fivefold (9.1%) relative to that of the Sc-free case, whereas fracture stress was successfully retained at a value of 1815 MPa. The high plastic strain of Zr55Cu20Ni8Al10Ti5Sc2 BMG can be attributed to the localized nanocrystallization phenomenon under uniaxial compression and to the high relaxed excess free volume (REFV) in ZrCuNiAlTiSc BMGs. The high REFV prevented the expansion of shear bands, generated secondary shear bands, and finally increased plasticity.

    The effect of silicon on the microstructure and properties of aged Cu-2.2Ni-0.4Be alloy

    Zhao H.L.Fan Y.H.Dong X.L.Guo C.W....
    6页
    查看更多>>摘要:? 2022 Elsevier B.V.The effect of Si addition (0.2 wt%) on the precipitation evolution, mechanical properties and electrical conductivity of Cu-2.2Ni-0.4Be alloy were investigated, and the influencing mechanism was also discussed. The results show that Si can not only form δ phase with Ni, but also promote the nucleation and refine the size of NiBe phase, which increases the peak hardness from 282.3 HV to 308.2 HV. In addition, Si suppresses the NiBe phase coarsening under the over-aged condition, resulting in a much slower hardness and strength decline during the long time aging. Nevertheless, the electrical conductivity shows a slight decrease with Si addition, which is mainly attributed to the extra electronic scattering effect induced by the partial solution of Si.

    Development, characterisation, and modelling of processability of nitinol stents using laser powder bed fusion

    Jamshidi P.Attallah M.M.Panwisawas C.Langi E....
    10页
    查看更多>>摘要:? 2022 The AuthorsAdditive manufacturing (AM) of customised vascular or peripheral stents is of great potential for surgeons and patients, enabling the patients to have customised stents and achieving better outcomes from stenting procedures, with further advantages of having a resource efficient manufacturing process. In this study, the potential for AM of superelastic NiTi-based shape memory alloy (Nitinol) stents was investigated. Two stent designs, which are used for the treatment of complex peripheral artery stenosis in the lower limbs, were studied. Laser Powder Bed Fusion (LPBF) of two stent designs was studied to investigate the impact of the process parameters on the stent geometry, strut size, structural integrity and the phase transformations. The study demonstrated the successful manufacture of Nitinol stents via LPBF, with strut sizes in the range between 250 μm and ≈ 560 μm. The elastic modulus of the stents was between 56 and 73 GPa, which matches well with the elastic modulus of standard austenitic Nitinol. Chemical etching was used to reduce the strut diameter and to remove the partially melted particles. It was shown that the laser energy input has a vital role in controlling the Ni-evaporation and the subsequent changes in the transformation temperatures, as well as the morphology of the stents. The lower energy input results in a reduced Ni-evaporation, maintaining the austenite finish temperature at the expected range, in addition to generating a good build morphology.

    Multifunctional nanostructured NiTi alloy with Invar, Elinvar and Rinvar properties

    Deng Z.Li Q.Sun Q.Onuki Y....
    13页
    查看更多>>摘要:? 2022 Elsevier B.V.A multifunctional NiTi alloy with Invar (dimension-invariant), Elinvar (elastic modulus-invariant) and Rinvar (resistivity-invariant) properties over the temperature range from 125 K to 375 K is fabricated through cold rolling of 60% thickness reduction. The underlying microstructure of such multifunctional NiTi alloy mainly consists of B2 and B19′ nanocrystals which can continuously undergo a small fraction of thermally induced B2?B19′ phase transition over a wide temperature range. Such phase transition can induce a negative thermal expansion to compensate for the positive expansions of the B2 and B19′ phases and thus yield the Invar property. Meanwhile, the opposite temperature dependences of elastic modulus of the B2 and B19′ phases can compensate each other and cause the macroscopic overall Elinvar property. In addition, the presence of nanocrystals enhances the negative temperature dependence of resistivity (TDR) caused by boundary scattering, which compensates for the positive TDR due to background scattering and thus leads to the Rinvar behavior. The three compensation mechanisms in the dual-phase nanostructure can also be exploited in other shape memory alloys to obtain the Invar, Elinvar and Rinvar properties so as to broaden their applications.