Strted in 1985 Monthly
ISSN 1005-0302
CN 21-1315/TG
Impact factor:3.609

The journal has been awarded the excellent periodical in China, and its articles are covered by SCI, EI, CA, SA, JST, RJ, CSA, MA, EMA, AIA etc., PASCAL web. ISI web of Science,SCOPUS.

  Current Issue
      20 September 2018, Volume 34 Issue 9 Previous Issue   
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    Orginal Article
    Layered double hydroxide coatings on magnesium alloys: A review
    Guo Lian, Wu Wei, Zhou Yongfeng, Zhang Fen, Zeng Rongchang, Zeng Jianmin
    J. Mater. Sci. Technol., 2018, 34 (9): 1455-1466.  DOI: 10.1016/j.jmst.2018.03.003
    Abstract   HTML   PDF (4580KB) ( 79 )

    Layered double hydroxides (LDHs) as a class of anionic clays have extensive applications due to their unique structures. Nowadays, the emphasis is laid on the development of LDH coatings for corrosion resistance and medical applications. Thus, this review highlights synthetic methods of LDH coatings and LDH-based composite coatings on magnesium alloys. Special attention is focused on self-healing, biocompatible and self-cleaning LDH-based composite coatings on magnesium alloys.

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    Preparation, structure, properties, and application of copper nitride (Cu3N) thin films: A review
    Jiang Aihua, Qi Meng, Xiao Jianrong
    J. Mater. Sci. Technol., 2018, 34 (9): 1467-1473.  DOI: 10.1016/j.jmst.2018.02.025
    Abstract   HTML   PDF (1854KB) ( 21 )

    Copper nitride (Cu3N) thin films display typical trans-rhenium trioxide structures. They exhibit excellent physical properties, low cost, nontoxicity, and high stability under room temperature. However, they possess low-thermal decomposition temperature, and their lattice constant often changes significantly with prepared technologies or techniques, thereby enabling the transformation from insulators to semiconductors and even conductors. Moreover, Cu3N thin films are becoming the new research hotspot of optical information storage devices, microelectronic semiconductor materials, and new energy materials. In this study, existing major prepared technologies of Cu3N thin films are summarized. Influences of prepared technologies of Cu3N thin films on crystal structure of films, as well as influences of prepared conditions and methods (e.g., nitrogen pressure, deposition power, substrate temperature, and element addition) on crystal structure and optical, electrical, and thermal properties of films were analyzed. The relationship between crystal structure and physical properties of Cu3N thin films was explored. Finally, applications of Cu3N thin films in photoelectricity, energy sources, nanometer devices, and other fields were discussed.

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    Boosting efficiency and stability of perovskite solar cells with nickel phthalocyanine as a low-cost hole transporting layer material
    Haider Mustafa, Zhen Chao, Wu Tingting, Liu Gang, Cheng Hui-Ming
    J. Mater. Sci. Technol., 2018, 34 (9): 1474-1480.  DOI: 10.1016/j.jmst.2018.03.005
    Abstract   HTML   PDF (1619KB) ( 28 )

    The efficiency of perovskite solar cells (PSCs) has increased from around 4% to over 22% following a few years of intensive investigation. For most PSCs, organic materials such as 2,2′,7,7′-tetrakis(N,N-pdimethoxyphenylamino)-9,9′-spirobifluorene (spiro-OMeTAD) are used as the hole transporting materials (HTMs), which are thermally and chemically unstable and also expensive. Here, we explored nickel phthalocyanine (NiPc) as a stable and cost-effective HTM to replace the conventionally used spiro-OMeTAD. Because of its high carrier mobility and proper band alignments, we achieved a PCE of 12.1% on NiPc based planar device with short-circuit current density (Jsc) of 17.64 mA cm-2, open circuit voltage (Voc) of 0.94 V, and fill factor (FF) of 73%, outperforming the planar device based on copper phthalocyanine (CuPc) that is an outstanding representative of metal phthalocyanines (MPcs) reported. Moreover, the device with NiPc shows much improved stability compared to that based on the conventional spiro-OMeTAD as a result of NiPc’s high stability. Photoluminescence (PL) and Impedance spectroscopy analysis results show that thermally deposited NiPc has good hole-extraction ability. Our results suggest that NiPc is a promising HTM for the large area, low cost and stable PSCs.

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    Reduced graphene oxide/metal oxide nanoparticles composite membranes for highly efficient molecular separation
    Hussain Thebo Khalid, Qian Xitang, Wei Qinwei, Zhang Qing, Cheng Hui-Ming, Ren Wencai
    J. Mater. Sci. Technol., 2018, 34 (9): 1481-1486.  DOI: 10.1016/j.jmst.2018.05.008
    Abstract   HTML   PDF (1314KB) ( 23 )

    Graphene oxide (GO) membranes play an important role in various nanofiltration applications including desalination, water purification, gas separation, and pervaporation. However, it is still very challenging to achieve both high separation efficiency and good water permeance at the same time. Here, we synthesized two kinds of GO-based composite membranes i.e. reduced GO (rGO)@MoO2 and rGO@WO3 by in-situ growth of metal nanoparticles on the surface of GO sheets. They show a high separation efficiency of ~100% for various organic dyes such as rhodamine B, methylene blue and evans blue, along with a water permeance over 125 L m-2 h-1 bar-1. The high water permeance and rejection efficiency open up the possibility for the real applications of our GO composite membranes in water purification and wastewater treatment. Furthermore, this composite strategy can be readily extended to the fabrication of other ultrathin molecular sieving membranes for a wide range of molecular separation applications.

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    Influence of ZnO/graphene nanolaminate periodicity on their structural and mechanical properties
    Iatsunskyi Igor, Baitimirova Margarita, Coy Emerson, Yate Luis, Viter Roman, Ramanavicius Arunas, Jurga Stefan, Bechelany Mikhael, Erts Donats
    J. Mater. Sci. Technol., 2018, 34 (9): 1487-1493.  DOI: 10.1016/j.jmst.2018.03.022
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    Structural, electronic and mechanical properties of ZnO/Graphene (ZnO/G) nanolaminates fabricated by low temperature atomic layer deposition (ALD) and chemical vapor deposition (CVD) were investigated. We performed scanning and transmission electron microscopy (SEM/TEM), X-ray diffraction (XRD), electron energy loss spectroscopy (EELS), Raman spectroscopy, X-Ray photoelectron spectroscopy (XPS) and nanoindentation to characterize the ZnO/G nanolaminates. The main structural and mechanical parameters of ZnO/G nanolaminates were calculated. The obtained results were analyzed and interpreted taking into account mechanical interaction and charge effects occurring at the G-ZnO interface. The influence of graphene sublayers number on the mechanical behavior of the ZnO/G nanolaminates was studied. By reducing the bilayer thickness, the mechanical parameters of the films can be tuned (Young’s modulus 100-200 GPa, hardness 3-9 GPa). The softer response of the multilayers as compared to the single layers of ZnO and graphene was attributed to the structural changes in the ZnO layer and the interfaces. This study shows the mechanical behavior of ZnO/G nanolaminates and their influence on the development of novel electro-optical devices based on these structures.

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    Novel continuous single-step synthesis of nitrogen-modified TiO2 by flame spray pyrolysis for photocatalytic degradation of phenol in visible light
    Boningari Thirupathi, Nagi Reddy Inturi Siva, Suidan Makram, G.Smirniotis Panagiotis
    J. Mater. Sci. Technol., 2018, 34 (9): 1494-1502.  DOI: 10.1016/j.jmst.2018.04.014
    Abstract   HTML   PDF (2928KB) ( 8 )

    A novel rapid and continuous process has developed for the synthesis of nitrogen-doped TiO2 (N-TiO2) with flame spray pyrolysis (FSP) method. The nitrogen incorporation into TiO2 was achieved by a facile modification (addition of dilute nitric acid) in the precursor for the synthesis. The catalysts were characterized by X-ray diffraction, Raman spectroscopy, transmission electron microscopy, diffuse reflectance spectroscopy, and X-ray photoelectron spectroscopy. The doping of nitrogen into the TiO2 was confirmed by X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray (EDX) spectroscopy. The UV-vis spectra of the modified catalysts (with primary N source) exhibited band-gap narrowing for 4N-TiO2 with band gap energy of 2.89 eV, which may be due to the presence of nitrogen in TiO2 structure. The introduction of secondary N-source (urea) into TiO2 crystal lattice results in additional reduction of the band gap energy to 2.68 eV and shows a significant improvement of visible light absorption. The N-TiO2 nanoparticles modified by using secondary N-source showed significant photocatalytic activity under visible light much higher than TiO2. The higher activity is attributed to the synergetic interaction of nitrogen with the TiO2 lattice. The lowering of the band-gap energy for the flame made N-doped TiO2 materials implies that the nitrogen doping in TiO2 by aerosol method is highly effective in extending the optical response of TiO2 in the visible region. The nitrogen atomic percentage has increased monotonically (0.09%-0.15%) with the increase in primary nitrogen source (nitric acid), and significantly boosted to 0.97% when secondary nitrogen source (urea) was introduced. The highest rate of phenol degradation was obtained for catalysts with secondary N source due to increase in N content in the catalyst.

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    Effects of electrochemical synthetic conditions on surface property and photocatalytic performance of copper and iron-mixed p-type oxide electrodes
    Hee Yoon Sun, Suk Han Dong, Kang Unseock, Yo Choi Seung, Yiming Wubulikasimu, Abdel-Wahab Ahmed, Park Hyunwoong
    J. Mater. Sci. Technol., 2018, 34 (9): 1503-1510.  DOI: 10.1016/j.jmst.2017.11.055
    Abstract   HTML   PDF (3666KB) ( 5 )

    Earth-abundant copper and iron-mixed oxide (CuO/CuFeO2; CFO) film electrodes are synthesized using an electrochemical deposition (ED) technique at two different ED potentials (-0.36 and -0.66 V vs saturated calomel electrode (SCE); denoted as ED-1 and ED-2, respectively). Then, their surface morphologies are compared, and the photo(electro)catalytic activities for the reduction of Cr(VI) are examined in aqueous solutions at pH 7 under simulated sunlight (AM 1.5G; 100 mW cm-2). The degree of the electrical potential applied to the ED process significantly affects the thickness of the synthesized electrode film and the intensity ratio of the diffraction peaks of CuO (111) and CuFeO2 (012). A 200 μm thick ED-2 sample with a distinct stacking of CuO on CuFeO2 exhibits a larger broadband absorption spectrum than the 50-μm thick ED-1 with less separate stacking. Furthermore, the ED-2 sample has a higher intensity ratio of the diffraction peaks of CuO (111) and CuFeO2 (012) than ED-1. As-synthesized ED-2 samples produce larger photocurrents, leading to faster Cr(VI) reduction on the surface under given potential bias (-0.5 V vs SCE) or bias-free conditions. The energy levels (i.e., flatband potential) for the two samples are almost the same (only 10 mV difference), presumably supposing that the enhanced photoactivity of the ED-2 sample for Cr(VI) reduction is due to the facilitated charge transfer. The time-resolved photoluminescence emission spectra analysis reveal that the lifetime (τ) of the charge carriers in the ED-1 sample is 0.103 ns, which decreases to 0.0876 ns in the ED-2. The ED-2 sample synthesized at a high negative potential is expected to contribute greatly to the application of other solar-to-fuel energy conversion fields as a highly efficient electrode material.

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    High efficiency visible-light-driven Fe2O3-xSx/S-doped g-C3N4 heterojunction photocatalysts: Direct Z-scheme mechanism
    Jourshabani Milad, Shariatinia Zahra, Badiei Alireza
    J. Mater. Sci. Technol., 2018, 34 (9): 1511-1525.  DOI: 10.1016/j.jmst.2017.12.020
    Abstract   HTML   PDF (5726KB) ( 4 )

    Several nanoporous Fe2O3-xSx/S-doped g-C3N4 (CNS) Z-scheme hybrid heterojuctions have been successfully synthesized by one-pot in situ growth of the Fe2O3-xSx particles on the surface of CNS. The characterization results show that S-doping in the g-C3N4 backbone can greatly enhance the charge mobility and visible light harvesting capability. In addition, porous morphology of hybrid composite provides available open pores for guest molecules and also improves light absorbing property due to existence of multiple scattering effects. More importantly, the Fe2O3-xSx nanoparticles formed intimate heterojunction with CNS and developed the efficient charge transfer by extending interfacial interactions occurred at the interfaces of both components. It has been found that the Fe2O3-xSx/CNS composites have an enhanced photocatalytic activity under visible light irradiation compared with isolated Fe2O3 and CNS components toward the photocatalytic degradation of methylene blue (MB). The optimal loaded Fe2O3-xSx value obtained is equal to 6.6 wt% that provided 82% MB photodegradation after 150 min with a reaction rate constant of 0.0092 min-1 which was faster than those of the pure Fe2O3 (0.0016 min-1) and CNS (0.0044 min-1) under the optimized operating variables acquired by the response surface methodology. The specific surface area and the pore volume of Fe2O3(6.6)/CNS hybrid are 33.5 m2/g and 0.195 cm3/g, which are nearly 3.8 and 7.5 times greater compared with those of the CNS, respectively. The TEM image of Fe2O3(6.6)/CNS nanocomposite exhibits a nanoporous morphology with abundant uniform pore sizes of around 25 nm. Using the Mott-Schottky plot, the conduction and valence bands of the CNS are measured (at pH = 7) equal to -1.07 and 1.48 V versus normal hydrogen electrode (NHE), respectively. Trapping tests prove that ·OH— and ·O2- radicals are major active species in the photocatalytic reaction. It has been established that formation of the Z-scheme Fe2O3(6.6)/CNS heterojunction between CNS and Fe2O3 directly produces ·OH as well as ·O2- radicals which is consistent with the results obtained from trapping experiments.

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    Synthesis, structure and photocatalysis properties of two 3D Isostructural Ln (III)-MOFs based 2,6-Pyridinedicarboxylic acid
    Zhang Chenchen, Wei Siyue, Sun Lixian, Xu Fen, Huang Pengru, Peng Hongliang
    J. Mater. Sci. Technol., 2018, 34 (9): 1526-1531.  DOI: 10.1016/j.jmst.2018.03.011
    Abstract   HTML   PDF (2753KB) ( 7 )

    Two new 3D metal-organic frameworks (MOFs) named [Pr2(PDA)3·3H2O]·H2O (1) and [Nd2(PDA)3·3H2O]·H2O (2) [2,6-Pyridinedicarboxylic acid (H2PDA)] were synthesized by solvothermal method. They were characterized by elemental analyses (EA), infrared spectroscopy (FT-IR), thermogravimetric analysis (TG), photocatalysis performance and single crystal X-ray diffraction studies (XRD). The XRD analysis indicated that MOFs (1) and (2) both belong to the monoclinic system with space group P2(1)/C. The structural model were drawn by the diamond software, and the structure revel that MOFs (1) and (2) adopt three-dimensional (3D) frameworks constructed by cross-linking of one-dimensional (1D) infinite chain secondary building unit (SBU) by 2,6-Pyridinedicarboxylic acid and hydrogen bond as linker. These frameworks feature channels inside which coordinated H2O solvent molecules are located. Thermogravimetric analysis showed that both MOFs are thermally stable, the photocatalytic evaluation showed the materials have a good prospect in degration methylene blue. As for complex 1, the decomposition efficiency of Methylene blue was about 91.08% after 130 min and the complex 2 reach 90.45% after 160 min under the sun light.

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    Synthesis of three-dimensionally ordered porous perovskite type LaMnO3 for Al-air battery
    Xiang Fuwei, Chen Xiuhua, Yu Jie, Ma Wenhui, Li Yuping, Yang Ni
    J. Mater. Sci. Technol., 2018, 34 (9): 1532-1537.  DOI: 10.1016/j.jmst.2018.01.010
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    LaMnO3 catalysts with three-dimensionally ordered holes perovskite structure were prepared via close-packed SiO2 template synthesized by St?ber-Frink method. SEM, XRD and BET were employed to characterize the microstructure, phases and specific surface area. CV method was used to the oxygen electrode behavior of catalysts. Diameter of the holes was about 330 nm, corresponding to the size of SiO2 template. Full-cell discharge tests were performed on aluminum-air battery fabricated by porous LaMnO3. Results showed that the discharge performance of porous LaMnO3 were 1.54 V, 1.42 V and 1.24 V respectively when the discharge currents were set at 5 mA/cm2, 10 mA/cm2 and 20 mA/cm2, respectively, which were higher than that of LaMnO3 prepared by coprecipitation method (1.33 V, 1.09 V, 0.63 V, respectively).

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    Formation of CMK-3/Co3O4 nanosheets on nickel foam with markedly enhanced pseudocapacitive properties
    Zhang Guoxiong, Chen Yuemei, Jiang Yingjian, Lin Chuan, Chen Yigang, Guo Haibo
    J. Mater. Sci. Technol., 2018, 34 (9): 1538-1543.  DOI: 10.1016/j.jmst.2017.12.018
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    Composites of mesoporous carbon (CMK-3) and Co3O4 nanosheets grown on nickel foam were successfully synthesized by a simple route. A bare Co3O4 film was synthesized for comparison. With the addition of CMK-3, the Co3O4 nanoparticles self-organize and agglomerate into nanosheets, showing a significant influence by CMK-3 on the morphology. The CMK-3/Co3O4 exhibits an optimal specific capacitance of 1131.3 F g-1 in 3 mol L-1 KOH aqueous electrolyte at 0.5 A g-1, and a retention ratio of 91% over 3000 cycles, both being much higher than that achieved from the bare Co3O4 film (727 F g-1 of specific capacitance, and 82% capacitance retention ratio), indicating that the CMK-3/Co3O4 nanosheets are very promising as electrode materials for supercapacitor applications.

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    Solvothermal-assisted morphology evolution of nanostructured LiMnPO4 as high-performance lithium-ion batteries cathode
    Zhu Chongjia, Wu Zhiqiu, Xie Jian, Chen Zhen, Tu Jian, Cao Gaoshao, Zhao Xinbing
    J. Mater. Sci. Technol., 2018, 34 (9): 1544-1549.  DOI: 10.1016/j.jmst.2018.04.017
    Abstract   HTML   PDF (3097KB) ( 7 )

    As a potential substitute for LiFePO4, LiMnPO4 has attracted more and more attention due to its higher energy, showing potential application in electric vehicle (EV) or hybrid electric vehicle (HEV). In this work, solvothermal method was used to prepare nano-sized LiMnPO4, where ethylene glycol was used as solvent, and lithium acetate (LiAc), phosphoric acid (H3PO4) and manganese chloride (MnCl2) were used as precursors. The crystal structure and morphology of the obtained products were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The electrochemical performance was evaluated by charge-discharge cycling, cyclic voltammetry and electrochemical impedance spectroscopy. The results show that the molar ratio of LiAc:H3PO4:MnCl2 plays a critical role in directing the morphology of LiMnPO4. Large plates transform into irregular nanoparticles when the molar ratio changes from 2:1:1 to 6:1:1. After carbon coating, the product prepared from the 6:1:1 precursor could deliver discharge capacities of 156.9, 122.8, and 89.7 mAh g-1 at 0.05C, 1C and 10C, respectively. The capacity retention can be maintained at 85.1% after 200 cycles at 1C rate for this product.

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    Exfoliation corrosion of extruded Mg-Li-Ca alloy
    Ding Zi-You, Cui Lan-Yue, Zeng Rong-Chang, Zhao Yan-Bin, Guan Shao-Kang, Xu Dao-Kui, Lin Cun-Guo
    J. Mater. Sci. Technol., 2018, 34 (9): 1550-1557.  DOI: 10.1016/j.jmst.2018.05.014
    Abstract   HTML   PDF (4362KB) ( 5 )

    Exfoliation on as-extruded Mg-1Li-1Ca magnesium alloy was investigated after an immersion in 3.5 wt% NaCl aqueous solution for 90, 120 and 150 days through optical microscope, digital camera, scanning electron microscope, electrochemical workstation, scanning Kalvin probe, X-ray diffraction and Fourier transform infrared spectroscope. The results demonstrated that exfoliation corrosion occurred on extruded Mg-1Li-1Ca alloy due to elongated microstructure parallel to surface, and delamination of lamellar structure resulted from galvanic effect and wedge effect. Skin layer with fine grains exhibited better corrosion resistance, whereas the interior with coarse grains and the intermetallic compound, Mg2Ca particles existing in a fibrous structure, dispersed along grain boundaries and extrusion direction in a line. Furthermore, galvanic effect between Mg2Ca particles and their neighboring α-Mg matrix facilitated dissolution of Mg2Ca particles and α-Mg matrix; wedge effect was caused by formation of corrosion products. Exfoliation corrosion of extruded Mg-Li-Ca alloys might be a synergic effect of pitting corrosion, filiform corrosion, intergranular corrosion and stress corrosion. Finally, exfoliation corrosion mechanism was proposed.

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    A novel approach to fabricate Zn coating on Mg foam through a modified thermal evaporation technique
    Wang Xingfu, Wang Xinfu, Wang Dan, Zhao Modi, Han Fusheng
    J. Mater. Sci. Technol., 2018, 34 (9): 1558-1563.  DOI: 10.1016/j.jmst.2017.12.019
    Abstract   HTML   PDF (2431KB) ( 9 )

    Zn enriched coatings with distinct microstructures and properties were fabricated on Mg foams by a modified thermal evaporation technique using a tubular resistance furnace. As the temperature and kinetic energy of Zn vapor varied along the tubular system, a spatial variation of preparation conditions was created and the obtained coatings were found to follow two growth mechanisms: a thermal diffusion pattern in high-temperature zone and the a relatively low-temperature deposition model. A Zn-based deposition coating with dense texture and nearly uniform structure was acquired while Mg foam was placed 20 cm far from the evaporation source, where the Zn vapor deposition model dominated the coating growth. Mechanical properties and bio-corrosion behaviors of the samples were investigated. Results showed that the Zn coatings brought dramatic improvements in compression strength, but exhibited differently in biodegradation performance. It was confirmed that the diffusion layer accelerated corrosion of Mg foam due to the galvanic effect, while the Zn-based deposition coating displayed excellent anti-corrosion performance, showing great potential as bone implant materials. This technique provides a novel and convenient approach to tailor the biodegradability of Mg foams for biomedical applications.

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    Effect of addition of Al-Si eutectic alloy on microstructure and mechanical properties of Mg-12wt%Li alloy
    Zhao Zilong, Xing Xuegang, Ma Jinyu, Bian Liping, Liang Wei, Wang Yide
    J. Mater. Sci. Technol., 2018, 34 (9): 1564-1569.  DOI: 10.1016/j.jmst.2018.03.007
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    Mg-12Li, Mg-12Li-3(Al-Si), Mg-12Li-7(Al-Si) and Mg-12Li-9(Al-Si) alloys (all in wt%) were fabricated by high frequency vacuum induction melting in a water cooled copper crucible. After subsequently hot-rolling and annealing, their microstructure and mechanical properties were investigated. Experimental results show that mechanical properties of Mg-12Li alloy were significantly improved by the addition of Al-Si eutectic alloy. Mg-12Li-7(Al-Si) alloy shows the highest strength of 196 MPa of the investigated alloys, which is about 1.8 times of the strength of Mg-12Li alloy, and maintains high elongation of 27%. The improved mechanical property with addition of Al and Si in the eutectic proportion into Mg-12Li alloy was attributed to the solution strengthening effect of Al and precipitation hardening effect from AlLi and Mg2Si precipitates.

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    Characterizations and anisotropy of cold-spraying additive-manufactured copper bulk
    Yang Kang, Li Wenya, Guo Xueping, Yang Xiawei, Xu Yaxin
    J. Mater. Sci. Technol., 2018, 34 (9): 1570-1579.  DOI: 10.1016/j.jmst.2018.01.002
    Abstract   HTML   PDF (5098KB) ( 9 )

    In this study, thick copper coatings were deposited by cold spraying (CS) as an additive manufacturing (AM) method. The interfacial microstructure evolution and mechanical behavior were investigated for the as-sprayed and annealed conditions. In addition, experiments together with numerical simulations were employed to study the recrystallization in different stages. Finally, the mechanical anisotropy of the CSed deposit was tested for the first time, being important to the applications of CS-AM. Results show that there exist two stages of recrystallization in the spraying and annealing processes. Heat treatment has a significant effect on mechanical properties, i.e., the tensile strength increases by 34.2% while microhardness decreases by 43.6%. The mechanical anisotropy analysis shows that the tensile strengths of different directions are completely different and show some regular changes.

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    Microstructure and mechanical properties of hot extruded 6016 aluminum alloy/graphite composites
    M. El-Sayed Seleman Mohamed, M.Z. Ahmed Mohamed, Ataya Sabbah
    J. Mater. Sci. Technol., 2018, 34 (9): 1580-1591.  DOI: 10.1016/j.jmst.2018.03.004
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    The incorporation of graphite particles into AA6016 aluminum alloy matrix to fabricate metal/ceramic composites is still a great challenge and various parameters should be considered. In this study, dense AA6016 aluminum alloy/(0-20 wt%) graphite composites have successfully been fabricated by powder metallurgy process. At first, the mixed aluminum and graphite powders were cold compacted at 200 MPa and then sintered at 500 °C for 1 h followed by hot extrusion at 450 °C. The influence of ceramic phases (free graphite and in-situ formed carbides) on microstructure, physical and mechanical properties of the produced composites were finally investigated. The results show that the fabricated composites have a relative density of over 98%. SEM observations indicate that the graphite has a good dispersion in the alloy matrix even at high graphite content. Hardness of all the produced composites was higher than that of aluminum alloy matrix. No cracks were observed at strain less than 23% for all hot extruded materials. Compressive strength, reduction in height, ultimate tensile stress, fracture stress, yield stress, and fracture strain of all Al/graphite composites were determined by high precision second order equations. Both compressive and ultimate tensile strengths have been correlated to microstructure constituents with focusing on the in-situ formed ceramic phases, silicon carbide (SiC) and aluminum carbide (Al4C3). The ductile fracture mode of the produced composites became less dominant with increasing free graphite content and in-situ formed carbides. Wear resistance of Al/graphite composites was increased with increasing graphite content. Aluminum/20 wt% graphite composite exhibited superior wear resistance over that of AA6016 aluminum alloy.

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    Thermodynamic investigation of phase equilibria in Al-Si-V system
    Luo Qun, Li Kang, Li Qian
    J. Mater. Sci. Technol., 2018, 34 (9): 1592-1601.  DOI: 10.1016/j.jmst.2018.01.004
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    The Al-Si-V system is assessed to understand the phase equilibria of V-containing (3d transition metal) Al-Si alloys, which are generally of great importance for technical applications. Four annealed alloys were prepared to study the phase equilibria of Al-rich corner (V ≤ 23.3 at.%, Si ≤ 57.6 at.%) in the temperature range of 500-930 °C. The microstructure and phase constituents of the samples were determined by X-ray diffraction (XRD) and scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectrometer (EDS). The existence of ternary phase τ (Al0.6Si1.4V, TiSi2-type) was confirmed with the composition ranging from 17.98 to 18.59 at.% Al and 48.89-49.20 at.% Si. However, it did not equilibrate with fcc(Al) below 868 °C, which was determined by differential scanning calorimetry (DSC). The Si3V5 appeared in Al58.5Si18.3V23.2 and Al64.7Si20.2V15.1 alloys annealed at 500 °C. It nearly disappeared after 3000 h-annealing and its thermodynamic stability was discussed. According to the measured phase relationships, the thermodynamic description of Al-Si-V system was optimized combing with the enthalpies of formation of binary and ternary compounds obtained by density functional theory (DFT). The Si-V system was modified to obtain the congruent liquidus of Si3V5 and enthalpy of formation of Si3V5 and Si2V with experimental data. By comparing the calculated phase equilibria and phase transitions with experimental data, it showed that a good agreement was reached. The description of Al-Si-V system could be used to guide the development of Al-Si alloys.

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    Interfacial failure behavior of PyC-Cf/AZ91D composite fabricated by LSEVI
    Li Shaolin, Qi Lehua, Zhang Ting, Zhou Jiming, Li Hejun
    J. Mater. Sci. Technol., 2018, 34 (9): 1602-1608.  DOI: 10.1016/j.jmst.2017.12.013
    Abstract   HTML   PDF (3305KB) ( 5 )

    Carbon fiber reinforced AZ91D matrix composites with pyrolytic (PyC) coating deposited on fiber surface (PyC-Cf/AZ91D composites) have been fabricated by Liquid-solid extrusion following vacuum pressure infiltration technique (LSEVI). Interfacial microstructure and failure behavior of the composites were investigated. Instead of interfacial reaction products, block-shaped interfacial precipitates Mg17Al12 were detected at the interface, which indicates that interfacial reaction was restrained by LSEVI and PyC coating. Nano-MgO was detected at the interface. Interfacial failure behavior of the PyC-Cf/AZ91D composites, which was the failure between PyC coating and AZ91D alloy due to the mismatch of thermal expansion and relatively poor bonding, was proposed. Fracture surface of the PyC-Cf/AZ91D composites was characterized by fibers pulling-out tests. PyC coating served not only as protection to the fibers, but also an adjustment of the interface of the composites.

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    Preparation of Al matrix nanocomposites by diluting the composite granules containing nano-SiCp under ultrasonic vibaration
    Lü Shulin, Xiao Pan, Yuan Du, Hu Kun, Wu Shusen
    J. Mater. Sci. Technol., 2018, 34 (9): 1609-1617.  DOI: 10.1016/j.jmst.2018.01.003
    Abstract   HTML   PDF (5500KB) ( 4 )

    In this work, an efficient process by diluting the nano-SiCp/Al composite granules in the molten matrix under ultrasonic vibration (UV) was developed to prepare metal matrix nano-composites (MMNCs). Millimeter-sized composite granules with high content of SiC particle (8 wt%) were specially fabricated by dry high-energy ball milling (HBM) without process control agent, and then remelted and diluted in molten Al alloy under UV. The MMNCs melt was finally squeeze cast under a squeeze pressure of 200 MPa. Microstructure of the composite granules during dry HBM was investigated, and the effect of UV on microstructure and mechanical properties of the MMNCs was discussed. The results indicate that nano-SiC particles are uniformly distributed in the nano-SiCp/Al composite granules, which are covered by vestures of pure Al. During diluting, nano-SiC particles released from the composite granules are quickly dispersed in the molten matrix by UV within 4 min. Microstructure of MMNCs is significantly refined under UV and squeeze casting, eutectic Si phase modified to fine islands with an average length of 1.4 μm. Tensile strength of the squeeze cast MMNCs with 1 wt% of nano-SiC particles is 269 MPa, which is improved by 25% compared with the A356 alloy matrix.

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    Indirectly extruded biodegradable Zn-0.05wt%Mg alloy with improved strength and ductility: In vitro and in vivo studies
    Xiao Chi, Wang Liqing, Ren Yuping, Sun Shineng, Zhang Erlin, Yan Chongnan, Liu Qi, Sun Xiaogang, Shou Fenyong, Duan Jingzhu, Wang Huang, Qin Gaowu
    J. Mater. Sci. Technol., 2018, 34 (9): 1618-1627.  DOI: 10.1016/j.jmst.2018.01.006
    Abstract   HTML   PDF (4096KB) ( 3 )

    As compared to permanent orthopedic implants for load-bearing applications, biodegradable orthopedic implants have the advantage of no need for removing after healing, but they suffer from the “trilemma” problem of compromising among sufficiently high mechanical properties, good biocompatibility and proper degradation rate conforming to the growth rate of new bones. In the present work, in vitro and in vivo studies of a Zn-0.05wt%Mg alloy (namely, Zn-0.05Mg alloy) were conducted with pure Zn as a control. The Zn-0.05Mg alloy is composed of a small amount of Mg2Zn11 phase embedded in the refined Zn matrix with an average grain size of ~20 μm. The addition of 0.05 wt% Mg into Zn significantly increases the ultimate tensile strength up to 225 MPa and the elongation to fracture to 26%, but has little influence on the in vitro degradation rate. Both Zn and Zn-0.05Mg alloy exhibit homogeneous in vitro degradation with a rate of about 0.15 mm/year. Based on the cytotoxicity evaluation, Zn and Zn-0.05Mg alloy do not induce toxicity to L-929 cells, indicating that they have little toxicity to the general functions of the animal. An in vivo biocompatibility study of Zn and Zn-0.05Mg alloy samples by placing them in a rabbit model for 4, 12 and 24 weeks, respectively did not show any inflammatory cells, and demonstrated that new bone tissue formed at the bone/implant interface, suggesting that Zn and Zn-0.05Mg alloy promote the formation of new bone tissue. The in vivo degradation of Zn and Zn-0.05Mg alloy does not bring harm to the important organs and their cell structures. More interestingly, Zn and Zn-0.05Mg alloy exhibit strong antibacterial activity against Escherichia coli and Staphylococcus aureus. The above results clearly demonstrate that the Zn-0.05Mg alloy could be a potential biodegradable orthopedic implant material.

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    Achieving superior mechanical properties in friction lap joints of copper to carbon-fiber-reinforced plastic by tool offsetting
    Wu L.H., Nagatsuka K., Nakata K.
    J. Mater. Sci. Technol., 2018, 34 (9): 1628-1637.  DOI: 10.1016/j.jmst.2018.04.015
    Abstract   HTML   PDF (4397KB) ( 3 )

    It is a challenge to achieve a sound welded metal/carbon-fiber-reinforced thermoplastic (CFRTP) joint with high strength and few bubbles. In this study, sound lap joints of Cu and CFRTP were obtained by friction lap joining (FLJ) directly at rotation rates of 600-2000 rpm, with the welding tool at the joint center and offsetting the tool 7 mm away from the center toward the retreating side, respectively. Tool offsetting reduced the non-uniform temperature distribution in the lap joints resulting from the high conductivity of Cu, which not only enhanced the tensile shear force from 0.89-2.25 kN to 1.71-3.54 kN, with the maximum increasing rate of 135%, but also reduced the bubble area to only 19% of the original level of 2000 rpm. It is the first time to report a high-quality Cu/CFRTP joint with a high strength and few bubbles. The large increase of the strength after tool offsetting was attributed to the increase of the joining area, the decrease of bubbles and the decrease of the CFRTP degradation. The details on the generation, quantitative distribution and expulsion of the bubbles in the FLJ joints were discussed.

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    Novel ternary g-C3N4/Fe3O4/MnWO4 nanocomposites: Synthesis, characterization, and visible-light photocatalytic performance for environmental purposes
    Mousavi Mitra, Habibi-Yangjeh Aziz, Seifzadeh Davod
    J. Mater. Sci. Technol., 2018, 34 (9): 1638-1651.  DOI: 10.1016/j.jmst.2018.05.004
    Abstract   HTML   PDF (6310KB) ( 6 )

    The g-C3N4/Fe3O4/MnWO4 nanocomposites were prepared by a refluxing-calcination procedure. Visible-light-induced photocatalytic experiments showed that the g-C3N4/Fe3O4/MnWO4 (10%) nanocomposite has excellent ability to degrade a range of contaminants including rhodamine B, methylene blue, methyl orange, and fuchsine, which is about 7, 10, 25, and 31 times of the g-C3N4 photocatalyst, respectively. Reactive species trapping experiments revealed that superoxide anion radicals play major role in the photodegradation reaction of rhodamine B (RhB). After the treatment process, the utilized photocatalyst was magnetically recovered and reused with negligible loss in the photocatalytic activity, which is vital in the photocatalytic processes. Finally, a mechanism was proposed for the enhanced interfacial carrier separation and transfer and the improved photocatalytic performance.

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    Joining of Cf/SiBCN composite with CuPd-V filler alloy
    Li Wen-Wen, Chen Bo, Cao La-Mei, Liu Wei, Xiong Hua-Ping, Cheng Yao-Yong
    J. Mater. Sci. Technol., 2018, 34 (9): 1652-1659.  DOI: 10.1016/j.jmst.2018.01.001
    Abstract   HTML   PDF (3147KB) ( 2 )

    Two compositions of CuPd-V system filler alloy were designed for joining the Cf/SiBCN composite. Their dynamic wettability on the Cf/SiBCN composite was studied with the sessile drop method. The CuPd-8V alloy exhibited a contact angle of 57° after holding at 1170 °C for 30 min, whereas for CuPd-13V alloy, a lower contact angle of 28° can be achieved after heating at 1200 °C for 20 min. Sound Cf/SiBCN joints were successfully produced using the latter filler alloy under the brazing condition of (1170-1230)°C for 10 min. The results showed that the active element V strongly diffused to the surface of Cf/SiBCN composite, with the formation of V2C/VN reaction layer. The microstructure in the central part of the joint brazed at 1200 °C was characterized by the V2C/VN particles distributing scatteringly in CuPd matrix. The corresponding joints showed the maximum three-point bend strength of 82.4 MPa at room temperature. When the testing temperature was increased to 600 °C, the joint strength was even elevated to 108.8 MPa. Furthermore, the joints exhibited the strength of 92.4 MPa and 39.8 MPa at 800 °C and 900 °C, respectively.

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    Effect of fluoride on the corrosion behavior of nanostructured Ti-24Nb-4Zr-8Sn alloy in acidulated artificial saliva
    Li Ji, Bai Yun, Fan Zhidong, Li Shujun, Hao Yulin, Yang Rui, Gao Yongbo
    J. Mater. Sci. Technol., 2018, 34 (9): 1660-1670.  DOI: 10.1016/j.jmst.2018.01.008
    Abstract   HTML   PDF (4048KB) ( 5 )

    The surface of titanium dental implants is highly susceptible to aggressive fluoride ions in the oral environment. Nanotechnology has proven an effective approach to improve the stability and corrosion resistance of titanium by applying a passive film. In this study, we investigated the effects of fluoride on the corrosion behavior of nanostructured (NS) Ti-24Nb-4Zr-8Sn (Ti2448) alloy in acidulated artificial saliva (AAS) at 37 °C, and then conducted comparisons with its coarse grained (CG) counterpart. Electrochemical techniques, such as potentiodynamic polarization and electrochemical impedance spectroscopy (EIS), as well as surface analysis including X-ray photoelectron spectroscopy (XPS) with argon ion sputtering, and scanning electronic microscopy (SEM) were employed to evaluate the effects of fluoride on sensitivity to pitting and the tolerance of Ti2448 to fluoride in AAS solution. The results demonstrate that corrosion current density increased with F- concentration. In all respects, the NS Ti2448 alloy presented corrosion resistance superior to that of its coarse grained (CG) counterpart at low F- concentrations (≤0.1%). Furthermore, a high content of F- (1%) was shown to promote the active dissolution of both alloys by increasing the rate of corrosion. Following immersion in the fluoridated AAS solution for 60 days, a tissue-friendly compound, Ca3(PO4)2, was detected on the surface of the NS when F- = 0.01% and Na2TiF6 was identified as the main component in the corrosion products of the CG as well as NS Ti2448 alloys when F- = 1%. High concentrations of F- produced pitting corrosion on the CG alloy, whereas NS Ti2448 alloy presented general corrosion in the form of lamellar separation under the same conditions. These findings demonstrate the superior corrosion resistance of the NS Ti2448 alloy as well as lower pitting sensitivity and higher tolerance to fluoride due mainly to grain refinement.

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    Role of Co in formation of Ni-Ti clusters in maraging stainless steel
    Tian Jialong, Babar Shahzad M., Wang Wei, Yin Lichang, Jiang Zhouhua, Yang Ke
    J. Mater. Sci. Technol., 2018, 34 (9): 1671-1675.  DOI: 10.1016/j.jmst.2018.04.020
    Abstract   HTML   PDF (2461KB) ( 5 )

    The effect of Co addition on the formation of Ni-Ti clusters in maraging stainless steel was studied by three dimensional atom probe (3DAP) and first-principles calculation. The cluster analysis based on the maximum separation approach showed an increase in size but a decrease in density of Ni-Ti clusters with increasing the Co content. The first-principles calculation indicated weaker Co-Ni (Co-Ti) interactions than Co-Ti (Fe-Ti) interactions, which should be the essential reason for the change of distribution characteristics of Ni-Ti clusters in bcc Fe caused by Co addition.

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    Strain-induced formation of a gradient nanostructured surface layer on an ultrahigh strength bearing steel
    Zhang K., Wang Z.B.
    J. Mater. Sci. Technol., 2018, 34 (9): 1676-1684.  DOI: 10.1016/j.jmst.2017.12.012
    Abstract   HTML   PDF (4741KB) ( 11 )

    In the present work, an ultrahigh strength bearing steel (AISI 52100) was subjected to surface mechanical rolling treatment (SMRT) at room temperature. Microstructural observations showed that martensitic laths, twins and cementite particles in the initial microstructure underwent distinct plastic strains and were gradually refined into nanostructures. Consequently, a gradient nanostructured (GNS) surface layer with a mean grain size of ~24 nm at the top surface was obtained on the bearing steel, resulting in an increment of ~20% in the surface hardness. Analyses based on microstructural evolution, phase constitution and in-depth hardness distribution revealed a mechanically induced formation mechanism of the GNS surface layer. The multiple surface severe plastic deformation under fine lubrication and cooling during SMRT contributed to the formation of a thick hardened surface layer on the bearing steel.

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    Effect of grain size on mechanical property and corrosion resistance of the Ni-based alloy 690
    Lv Jinlong
    J. Mater. Sci. Technol., 2018, 34 (9): 1685-1691.  DOI: 10.1016/j.jmst.2017.12.017
    Abstract   HTML   PDF (2836KB) ( 14 )

    Mechanical property of coarse grained and nano/ultrafine grained alloy 690 and their corrosion resistance after immersion in high temperature borate buffer solution were investigated. The grain refinement significantly enhances the tensile strength of the alloy 690. In addition, the grain refinement facilitates the formation of the deformation twin which improves the ductility of the alloy 690. It has been found that the grain refinement promotes to form more Cr2O3 on the surface of the alloy 690 in high temperature borate buffer solution. At the same time, the grain refinement inhibits the formation of spinel type oxides. More hematite type oxides formed on nano/ultrafine grained alloy 690 improves its corrosion resistance in borate buffer solution. The hematite type oxides have a lower concentration of point defect than that of the spinel type oxides, which results in an excellent corrosion resistance of nano/ultrafine grained alloy 690. These results are supported by the Mott-Schottky analysis and the point defect model.

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    Stable controlled growth of 3D CuO/Cu nanoflowers by surfactant-free method for non-enzymatic hydrogen peroxide detection
    Yuan Ruimei, Li Hejun, Yin Xuemin, Zhang Leilei, Lu Jinhua
    J. Mater. Sci. Technol., 2018, 34 (9): 1692-1698.  DOI: 10.1016/j.jmst.2017.11.030
    Abstract   HTML   PDF (2835KB) ( 2 )

    Sensitive, convenient and rapid detection of hydrogen peroxide (H2O2) is highly desirable in fields like fundamental biological research, food industries, and clinical & environmental analysis. Herein, a hierarchical porous CuO/Cu flower-like active electrode material for non-enzymatic H2O2 sensor was synthesized via a low-cost and one-step chemical oxidation of Cu powder in water bath without surfactants. In order to discuss the growth mechanism of the product, products with different growth time length were fabricated. The electro-catalysis of all products were first exhibited by cyclic-voltammetry, and the product under 6 h reaction shows the best result. The detailed electro-catalytic behaviors of the best product (under 6 h reaction) are characterized by cyclic-voltammetry and amperometry under alkaline conditions. The materials have high sensitivity of 103 μA mM-1 cm-2 (R2 = 0.9979), low detection limit of 2 μmol/L and wide concentration range (from 2 μmol/L to 19.4 mmol/L). Large specific surface area and stabled nanostructure enabled good features, such as stability and sensitivity for the H2O2 determination.

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    Experimental and computational investigations of LaNi5-xAlx (x = 0, 0.25, 0.5, 0.75 and 1.0) tritium-storage alloys
    Liu Guoliang, Chen Demin, Wang Yuanming, Yang Ke
    J. Mater. Sci. Technol., 2018, 34 (9): 1699-1712.  DOI: 10.1016/j.jmst.2018.01.007
    Abstract   HTML   PDF (3964KB) ( 5 )

    Although already scientists in recent years have reported some experimental and theoretical results of La-Ni-Al series of tritium-storage alloys, several key aspects remain the subject of considerable debate. In an effort to interpret some of these unknowns, we have performed experimental and theoretical investigations for LaNi5-xAlx (x = 0, 0.25, 0.5, 0.75 and 1.0) tritium-storage alloys. Firstly, the XRD characterization indicates that the unit cell volumes of LaNi5-xAlx increase with Al content in alloys. Secondly, the PC-isotherm measurement of LaNi5-xAlx alloys shows that their hydrogen absorption/desorption plateau pressures reduce with the increase of Al content while their plateau widths narrow simultaneously. The deuterium absorption/desorption plateaus have a similar trend to hydrogen’s except for their plateaus being higher than hydrogen’s. To explain the above experimental findings, a series of calculations based on density functional theory (DFT) and frozen phonon approach have been performed. The results manifest that: (1) the partial substitutions of Al for Ni reduce the hydrogen formation energies of LaNi5-xAlxH and the number of available interstitial sites, and therefore lead to the absorption/desorption plateau pressures being reduced and the plateau widths being narrowed down at the same experimental temperatures; (2) the covalent interaction between H and Ni is an important factor for estimating the stability of LaNi5-xAlx-H system; (3) since the calculated enthalpy change ΔH is generally more accurate than the calculated entropy change ΔS with respect to the corresponding experimental value for each LaNi5-xAlx-H (or D), the curves of ΔH vs. hydrogen storage capacity instead of Van’t Hoff relation, can be used to predict the experimental plateau pressures of LaNi5-xAlx-H (D or T) at a given temperature; (4) the hydrogen isotope effect of LaNi5-xAlx-H (D or T) system can be quantitatively described as a linearity relation between ΔZPE + ΔHvib and (Q = H, D, T). From the good agreement between the predicted and experimental and , it is deduced that predicting of LaNi5-xAlxT is feasible. The procedure of pre-computing and comparing curves of ΔH vs. hydrogen storage capacity proposed in this paper provided an attractive tool to increase the efficiency of experimental alloying design of hydrogen (deuterium or tritium) storage materials.

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ISSN: 1005-0302
CN: 21-1315/TG
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