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      20 June 2020, Volume 48 Issue 6 Previous Issue    Next Issue
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    Electromagnetic Metamaterials Column
    Infrared stealth metamaterials
    Xiao-ming LIU, Zhi-yu REN, Lu-ping CHEN, Guo-jian LI, Qiang WANG, Ji ZHOU
    2020, 48 (6): 1-11.   DOI: 10.11868/j.issn.1001-4381.2019.001019
    Abstract ( 1466 ( PDF (6942KB)( 1102 Citation

    The basic principles and methods of infrared radiation and infrared stealth technology were discussed in this paper. It was found that flexible regulation of multi-band spectrum was the key to realize infrared stealth compatible with radar stealth, laser stealth and visible light stealth. The research status of traditional infrared stealth materials were summarized and the bottleneck of their development was clarified. Furthermore, the design idea, research basis and development advantages of infrared stealth metamaterials with spectral tailoring function were proposed. We reviewed the research status and development trend of the infrared stealth compatible with radar stealth, infrared stealth with infrared radiation window and infrared stealth compatible with laser and visible light.

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    Research progress in terahertz metamaterials and their applications in imaging
    Xiao-jian FU, Lei SHI, Tie-jun CUI
    2020, 48 (6): 12-22.   DOI: 10.11868/j.issn.1001-4381.2019.000849
    Abstract ( 1164 ( PDF (6845KB)( 1180 Citation

    Electromagnetic metamaterials have attracted more and more research interest due to their exotic physical properties and important applications in manipulating electromagnetic waves. In this paper, the research progress in terahertz metamaterials and their applications in imaging was reviewed: firstly, the research of terahertz metamaterials was overviewed, and tunable and reconfigurable terahertz metamaterials as well as terahertz digitally coding and field-programmable metamaterials were discussed in detail; then, the applications of terahertz metamaterials in imaging were illustrated, including terahertz imaging technologies based on metasurface lenses, metamaterial absorbers, reconfigurable metasurfaces, and field-programmable metasurfaces; finally, the prospects of terahertz metamaterials and their applications in imaging were provided.Reconfiguration and in telligence of the functions will be an important development direction of terahertz metamaterials, and the emerging information metamaterials which integrate meta meaterials and information technology will enable more efficient and convenient terahertz imaging.

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    Research progress in broadband absorber based on artificial electromagnetic medium
    Hong-yan DU, Zi-dong ZHANG, Rui TIAN, Wen-jin ZHANG, Jian ZHANG, Xin-yu LIU, Kai SUN, Run-hua FAN
    2020, 48 (6): 23-33.   DOI: 10.11868/j.issn.1001-4381.2019.001015
    Abstract ( 642 ( PDF (4455KB)( 304 Citation

    Artificial electromagnetic medium can effectively expand the absorption bandwidth of the absorber, which has aroused wide attention of researchers at home and abroad. The main typical structure and application of broadband absorbers based on artificial electromagnetic medium were reviewed in recent years. The mechanism of artificial electromagnetic medium structure in improving the absorption rate of the absorber was analyzed. The theoretical model of widening the bandwidth of the absorber based on lumped elements was introduced. The important role of artificial electromagnetic medium in expanding the absorbing bandwidth was emphasized. Finally, the application prospect of electromagnetic medium in the field of science and technology was prospected, and it was pointed out that the future development trend of broadband electromagnetic absorbers mainly focuses on coordinability, multi-physics coupling and low-cost production, especially the efficient large-area low-cost production process will become important for the future.

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    Research progress in hyperbolic metamaterials and sensors
    Hong-ya WU, Yun YANG, Guang-lei ZHANG, Yang BAI, Ji ZHOU
    2020, 48 (6): 34-42.   DOI: 10.11868/j.issn.1001-4381.2019.001020
    Abstract ( 804 ( PDF (1837KB)( 507 Citation

    Metamaterials are artificial structures with extraordinary electromagnetic properties. Much attention has been attracted to metamaterials because of their electromagnetic properties like permittivity, permeability, and refractive index that traditional materials cannot achieve. Hyperbolic metamaterials show highly anisotropic dielectric tensors or permeability tensor, the components of which are negative in one or two spatial directions. Compared with other types of metamaterials, hyperbolic metamaterials are relatively easy to be fabricated at optical frequencies, broadband non-resonant and three-dimensional volume responses, and flexible wavelength tunability. In this review, definition, implementations of hyperbolic metamaterials, tunable and active hyperbolic metamaterials and developments of sensitive sensors are introduced in detail. The principle and progress of the hyperbolic metamaterials based on metal/dielectric multilayer structure and metal nanowire array as biosensors were focused and discussed in this paper, and it was pointed out that the long-term goal of the development of hyperbolic metamaterials sensors is simple structure, easy preparation, wide band and multivariate analysis.

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    Ferromagnetic/ferroelectric composites and microwave properties of its metamaterial structure
    Hong-xia GUO, Jia-meng ZHANG, Qing-min WANG, Ke BI
    2020, 48 (6): 43-49.   DOI: 10.11868/j.issn.1001-4381.2019.000980
    Abstract ( 632 ( PDF (5499KB)( 209 Citation

    A series of YIG/BST ferromagnetic/ferroelectric composites were prepared by solid-state reaction using yttrium iron garnet (Y3Fe5O12) and barium titanate (Ba0.5Sr0.5TiO3). The phase and microstructure of the composites were investigated by XRD and SEM, and the dielectric and magnetic property were studied in detail. The results show that the ferroelectric phase and ferromagnetic phase exist independently when the composite is sintered at a certain temperature; (1-x)YIG-xBST (x=0.1, 0.2, 0.3, 0.4, 0.5) composites possess great dielectric properties: at room temperature, with increasing frequency (102-106Hz), the dielectric constant of each component composite and the dielectric loss decreases gradually; when the frequency is 1 MHz, the dielectric constant of the composite increases with the increase of BST content, and the dielectric loss first drops and then stabilizes; with the increase of temperature (0-400 ℃), the dielectric constant and dielectric loss of each composite at different frequencies gradually increase. The composites exhibit the hysteresis loop shape of a typical soft magnet. As the BST content increases, the saturation magnetization (Ms) gradually decreases, and the magnetic permeability decreases. The microwave property of the composite based metamaterial structure was studied. The results show that it can realize magnetic tunability.

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    Review
    Research and application of artificial solid electrolyte interphases for lithium metal anodes protection
    Xin QI, Chen WANG, Wen-zheng NAN, Qi-hu HONG, Si-kan PENG, Shao-jiu YAN
    2020, 48 (6): 50-61.   DOI: 10.11868/j.issn.1001-4381.2019.001209
    Abstract ( 734 ( PDF (2032KB)( 491 Citation

    Lithium metal has the lowest redox potential (-3.04 V vs standard hydrogen electrode) and extremely high specific capacity (3860 mAh·g-1), making it the ideal anodes materials for lithium secondary batteries. However, during the electrochemical cycling, due to the nonuniform nucleation growth of lithium, lithium dendrites are generated on its surface, and continue to grow and pierce the separator, causing short-circuiting of the batteries and even a fire. In the face of increasing energy density requirements, lithium metal anodes have once again become the focus all over the world. Therefore, it is necessary to protect the lithium metal anodes, suppress negative problems, and exert high performance. The artificial solid electrolyte interphase technology is an effective protection strategy for lithium metal anodes, which is essentially coating the surface of lithium metal with protective layers in advance. The artificial solid electrolyte interphase layers should have good ionic conductivity and electrochemical stability, high barrier property and mechanical strength, which can make the lithium metal anodes have high efficiency, long-term life and dendrites-free properties.The artificial solid electrolyte interphase technology brings hope to lithium metal anodes applications. In this review, the research progress of artificial solid electrolyte interphase strategy for lithium metal anodes protection in recent years was reviewed, the preparation methods, structural characteristics, cycling performances of lithium metal anodes and other aspects were introduced in detail. The specific application and performances of artificial solid electrolyte interphases in lithium secondary batteries were for summarized. Moreover, the current problems were analysed and it was pointed out that for researches of lithium metal anodes, not only the mechanism research need to be strengthed, but also needs to be combined with practical applications.

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    Research progress of non-precious metal oxide coated anodes for electrocatalytic degradation of organic pollutants in water
    Chang-bin TANG, Yu-xuan LU, Fei WANG, Ping HUANG, Li-hua YU, Juan-qin XUE
    2020, 48 (6): 62-72.   DOI: 10.11868/j.issn.1001-4381.2019.000422
    Abstract ( 635 ( PDF (3545KB)( 319 Citation

    Electrocatalytic oxidation is an effective water treatment method for degradation of organic pollutants, and the key to the technical advantages lies in anode materials with excellent performance. Ti-based anode can be conveniently prepared by coating a titanium substrate with a non-noble metal oxide such as lead, tin or manganese. At the same time, the anode materials with outstanding stability and catalytic activity can be obtained by various preparation and modification methods, which make it have great development prospects. Research progress on the stability optimization of non-precious metal oxide coating anode was reviewed from the perspective of substrate processing, intermediate layer optimization and surface modification. Catalytic activity enhancement was summarized from the aspect of surface synergism and the expansion of the action area, and the modification mechanism of coating anodes was commented. Finally, in order to promote the development of the electrocatalytic oxidation anode materials and its application in water treatment, development direction of non-precious metal oxide coated anodes was pointed out.

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    Research progress in superhydrophobic anticorrosion coatings
    Xia WANG, Hui WANG, Li HOU, Huan JIANG, Wen-jie ZHOU
    2020, 48 (6): 73-81.   DOI: 10.11868/j.issn.1001-4381.2018.000632
    Abstract ( 961 ( PDF (1832KB)( 669 Citation

    The corrosion of materials brings serious economic and safety problems to the society. Superhydrophobic coatings have great potential for anti-corrosion due to the special structure of the surface. In this paper, the establishment and development of several superhydrophobic theoretical models were reviewed. The theoretical basis and existing problems of applying superhydrophobic coatings to corrosion protection were analyzed. Several methods, such as hydrothermal method, sol-gel method and etching method, were discussed. The commonly used superhydrophobic coating preparation methods were summarized. In the field of large-scale application and corrosion protection of superhydrophobic coating, it is necessary to study the corrosion protection behavior of the coating in theory, simplify the process, reduce the cost, and improve the mechanical stability of the coating and the controllable transformation of water drop on the surface of the coating.

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    State-of-art of nitride microwave absorption materials
    Yi CUI, Heng-yong WEI, Jing-kai YANG, Bin ZHU, Jing-long BU, Bo LIANG
    2020, 48 (6): 82-90.   DOI: 10.11868/j.issn.1001-4381.2019.000829
    Abstract ( 787 ( PDF (1865KB)( 517 Citation

    With the increasing development of the microwave absorption materials, nitride material has attracted more attentions, and is expected to become a new kind of potential microwave absorbing materials due to their excellent physical and chemical properties. In this paper, the research status of nitride microwave absorbing materials was discussed, and the research status of titanium nitride, iron nitride, manganese nitride, boron carbon nitride and alloy nitride was summarized in detail. Finally, the developing trend of nitride materials was prospected from the aspects of morphology control, bionic structure design, high temperature microwave absorption and microwave absorption mechanism.

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    Research Article
    Preparation of flower-like CdO microspheres and its catalytic performances towards thermal decomposition of ammonium perchlorate
    Fan-da ZENG, Gang LI
    2020, 48 (6): 91-97.   DOI: 10.11868/j.issn.1001-4381.2019.000287
    Abstract ( 601 ( PDF (2299KB)( 155 Citation

    A two-step method involving solvothermal synthesis and annealing was used to prepare the flower-like CdO microspheres.The flower-like precursor microspheres assembled by nano-flakes were firstly fabricated by the solvothermal method using Cd(Ac)2 as source materials in methanol system.Through calcining the precursor, CdO porous microspheres with well-preserved morphologies were then obtained.X-ray diffraction(XRD), Fourier transform infrared spectroscopy(FT-IR), thermal gravimetry(TG), scanning electron microscopy(SEM), transmission electron microscopy(TEM) and N2 adsorption-desorption were used to characterize the phases, chemical composition, morphologies and pore structures of the samples.Differential scanning calorimetry(DSC) was employed to evaluate the catalytic performance of these CdO microspheres for thermal decomposition of ammonium perchlorate(AP).The results show that the as-obtained CdO microspheres play a positive role in catalyzing the thermal decomposition of AP.Adding 2%(mass fraction)CdO microspheres into AP, the peak temperature decreases from 444.4 ℃ to 402.8 ℃ and the heat released increases from 586.9 J/g to 1091.7 J/g.The activation energy of AP decomposition significantly decreases from 280.5 kJ/mol to 83.78 kJ/mol.Based on the results, a possible catalytic mechanism for the thermal decomposition of AP over flower-like CdO microspheres is proposed.

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    Synthesis and electrochemical performance of CuO/CuxSy octahedral core-shell structure
    Zhen-wei WANG, Xiao-shan YANG, Ya-yun ZHENG, Ying-jiu ZHANG, Jie XU
    2020, 48 (6): 98-105.   DOI: 10.11868/j.issn.1001-4381.2019.000381
    Abstract ( 729 ( PDF (5015KB)( 205 Citation

    A copper oxide/copper sulphide (CuO/CuxSy)composite was simply synthesized through an ion-exchange process just at room temperature, owning a unique octahedral core-shell structure. By adjusting reaction time of sulfuration, the morphology and composition of CuO/CuxSy octahedral core-shell material were changed, which has an important influence on the electrochemical performance. XRD, SEM, TEM and XPS were conducted to analysize the morphology and structure of CuO/CuxSy composite. It shows the hollow composite possesses a shell layer with the interconnected CuxSy nanosheets and a CuO core-layer in the octahedron.The unique core-shell octahedral structure and the synergy between CuO and CuxSy are beneficial for the electrochemical process. When the reaction time is 6 h, as-obtained CuO/CuxSy core-shell octahedral material has a high specific capacity of 413.6 F·g-1 at a current density of 1 A·g-1, and better rate performance and stability even at a higher current density of 20 A·g-1.

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    Effect of stretching process on crystalline structures and alternating current conductivity of CNF/PVDF composites
    Li-li SUN, Nan WU, Rui PENG
    2020, 48 (6): 106-111.   DOI: 10.11868/j.issn.1001-4381.2019.000993
    Abstract ( 494 ( PDF (2663KB)( 242 Citation

    Carbon nanofiber (CNF)/poly (vinylidene fluoride) (PVDF) composites with different CNF concentrations from 1% (mass fraction, the same as below) to 5% were prepared into thin films via solution casting method firstly, followed by the stretching process. The effect of stretching process on the crystallization and alternating current (AC) conductivity of CNF/PVDF composites was discussed. The results reveal that the phase transformation from α- to β-crystal PVDF can be effectively induced by stretching process. Simultaneously, the crystallinity is decreased. On the other hand, CNFs in PVDF are re-oriented and the AC conductivity of CNF/PVDF composites is decreased, the percolation threshold of which is raised from 1% to a value between 3% and 5%.

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    Preparation and relevant properties of amorphous AlBN dielectric films
    Feng-feng LIU, Yu-xiong LI, Zhan-peng SUI, Yong CAI, Yong-hong ZHANG, Chun-ping JIANG
    2020, 48 (6): 112-117.   DOI: 10.11868/j.issn.1001-4381.2019.000323
    Abstract ( 487 ( PDF (2857KB)( 188 Citation

    Amorphous AlBN dielectric films were deposited on GaN (002) by pulsed laser deposition (PLD). The crystal structure and composition of the grown films were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Conductive atomic force microscope (CAFM) and I-V methods were also used to test the electrical properties of films with different thickness. The results show that the AlBN dielectric films with different thickness is amorphous, and the content of boron in all the films is about 6.7%(atom fraction). The root-mean-aquare (RMS) surface roughness Rq of the films with thickness of 3 nm and 18 nm are only 0.209 nm and 0.116 nm, respectively, indicating smooth surface of these AlBN film. When the voltage of ±10 V is applied, there is no obvious leakage current in the film with a thicknes of 18 nm. However, in the metal-insulator-metal (MIM) structure, a large leakage current appears in the 18 nm thin film structure, and the leakage current density is about -2×10-4 A/cm2 at -2 V.

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    Influence of Gd2O3 doping contents on conductivity of Ce1-xGdxO2-δ electrolyte
    Yuan-yuan LIU, Shu-ting LI, Jun PENG, Sheng-li AN
    2020, 48 (6): 118-124.   DOI: 10.11868/j.issn.1001-4381.2019.000322
    Abstract ( 565 ( PDF (3426KB)( 359 Citation

    Gd2O3 doped CeO2(GDC) was widely used in solid oxide fuel cell (SOFC) because of its high ionic conductivity at 500-700 ℃. However, during the SOFC operation, Ce4+ was reduced to Ce3+ at the anode side of the battery, resulting in electronic leakage, which leaded to the degradation of SOFC battery performance. The Ce1-xGdxO2-δ(x=0.05, 0.10, 0.15, 0.20, 0.25, mole fraction) solid electrolyte was prepared by sol-gel method. The effects of different Gd3+ doping amount on the total conductivity and electronic conductivity of GDC electrolyte were studied, and the relationships between the total conductivity, electronic conductivity, and temperature, oxygen partial pressure were analyzed. The results show that, when the Gd2O3 doping content is 0.20, the total conductivity of GDC reaches the highest 8.59×10-2 S·cm-1 at 750 ℃. The electronic conductivity decreases with the increase of Gd3+doping amount, and reaches the highest 6.47×10-4 S·cm-1 at 750 ℃ when Gd3+doping amount is 0.10. The GDC with doping amount of 0.20 highlights the highestionic conductivity because of its highest total conductivity and smaller electronic conductivity.

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    Preparation and oil absorption properties of PP non-woven nanofiber membranes by melt differential electrospinning
    Chao XIE, Jian XING, Yu-mei DING, Xun WANG, Wei-min YANG, Hao-yi LI
    2020, 48 (6): 125-131.   DOI: 10.11868/j.issn.1001-4381.2019.000486
    Abstract ( 606 ( PDF (2747KB)( 203 Citation

    Recycling is the most effective way to dispose of waste polymer materials. It can not only reduce the harm of polymer materials to the natural environment, but also achieve the purpose of saving cost and turning waste into treasure. A self-made melt differential electrospinning device was used to recover the degraded polypropylene (PP) non-woven fabric as a raw material, and the special powder for recycling and degrading PP non-woven fabric after acid treatment and adding different plasticizers with a mass fraction of 10%. A blend of materials of sodium stearate, acetyl tributyl citrate (ATBC), and dioctyl adipate (DOA) was spun, and a nanofiber membrane was prepared at 300 ℃. The optimum degradation time of PP nonwoven fabric spinning and the effect of adding different plasticizers on the morphology, oil absorption performance and reusability of PP-degraded non-woven fabric nanofibers were investigated. Studies have shown that the addition of plasticizer ATBC works best. When the spinning voltage is 40 kV, the spinning distance is 70 mm, the spinning temperature is 300 ℃, and the ATBC mass fraction is 10%, the fiber diameter is as fine as 1.13 μm. The fiber membrane oil absorption ratio is 115.4 g/g, and the oil retention ratio is 70.3 g/g, which are 4 times and 3 times that of the initially commercially available PP nonwoven fabric, and has good reusability.

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    Microstructure, bending and shear properties of 2.5D shallow cross-linked Cf/Al composites
    Jing-peng FENG, Huan YU, Zhi-feng XU, Chang-chun CAI, Zhen-jun WANG, Yin-sheng HU, Ya-na WANG
    2020, 48 (6): 132-139.   DOI: 10.11868/j.issn.1001-4381.2019.000648
    Abstract ( 677 ( PDF (7818KB)( 246 Citation

    2.5D shallow cross-linked Cf/Al composites with volume fraction of 50% were fabricated by vacuum pressure infiltration. The microstructure, bending and shear properties at room and high temperature were studied. The failure mechanism of bending and shear properties of the composites were analyzed. The results indicate that the warp and weft microstructures of 2.5D shallow cross-linked Cf/Al composites have some defects such as microvoid and fiber aggregation. The bending strength, bending modulus and shear strength of the composites at room temperature are 268.4 MPa, 75.2 GPa and 41.0 MPa, respectively. The bending strength, bending modulus and shear strength of the composites at 350 ℃ are 139 MPa, 70.9 GPa and 39.2 MPa, respectively. The bending strength, bending modulus and shear strength of the composites at 400 ℃ are 97.6 MPa, 68.5 GPa and 29.9 MPa, respectively.The bending failure is mainly caused by the compressive stress on the inner surface, which leads to press fracture of the warp fiber bundle and the extrusion deformation of the weft fiber bundle. Tensile failure of composites is not obvious with the increase of testing temperature at the outer side tension. Shear failure occurs first in the damage interface of the matrix and fiber bundle, the fiber bundle is pulled out and the fracture surface is not at the same level at room temperature, the fracture of the fiber bundle shows 45° failure at 350, 400 ℃.The buckling of the warp fiber bundle and the extrusion deformation degree of the weft fiber bundle become more and more serious with the increase of the test temperature.

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    Microstructure and mechanical properties of inertia friction welded joint of Ti-22Al-25Nb alloy
    Qiang ZHAO, Wen-hui ZHU, Tian-wei SHAO, Yan-lin SHUAI, Jia-tao LIU, Ran WANG, Li ZHANG, Xiao-bo LIANG
    2020, 48 (6): 140-147.   DOI: 10.11868/j.issn.1001-4381.2019.000842
    Abstract ( 612 ( PDF (5558KB)( 183 Citation

    The Ti-22Al-25Nb alloy was welded by inertia friction welded technology. The micros-tructure and microhardness of welded joints before and after heat treatment were studied.The tensile mechanical properties at 650 ℃ and 750 ℃ of welded joints were analyzed. The results show that the weld zone of the as-welded joint consists of B2 phase and a very small amount of residual α2phase. After heat treatment, the weld zone consists of B2 phase and O phase. The O phase is transformed from B2 phase, and there is no composition change during the phase transition process. The microhardness of the as-welded zone is higher than that of the base material. After heat treatment at 780 ℃ for 3 h, the microhardness of the welded zone increases significantly due to the precipitation of fine O phase. But the microhardness of the welded zone with heat treatment at 800 ℃ for 3 h is between that of the as-welded state and the heat treatment at 780 ℃ for 3 h. The specimen of high temperature tensile fracture in the base material, and the tensile fracture morphology presents ductile fracture feature with many small shallow dimples.

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    Effects of hot isostatic pressing and heat treatment process on microstructure and tensile properties of selective laser melting manufactured GH4169 alloy
    Lei SHI, Li-ming LEI, Wei WANG, Xin FU, Guang-ping ZHANG
    2020, 48 (6): 148-155.   DOI: 10.11868/j.issn.1001-4381.2019.000416
    Abstract ( 685 ( PDF (6070KB)( 262 Citation

    GH4169 alloys were manufactured by selective laser melting (SLM). The microstructure evolution and tensile properties of GH4169 alloys during hot isostatic pressing(HIP) and heat treatment(HT) process were analyzed by OM, SEM, EBSD and TEM. The results show that the grains of the as-deposited samples in the building direction are columnar, exhibit very fine cellular-dendritic structure with fine Laves phases precipitating in the interdendritic region. Most of porosities and Laves phases disappear after HIP, and the microstructure parallel to the building direction is transformed into equiaxed grains. Short rod-like δ phases are precipitated along grain boundaries after annealing at 980 ℃ for 1 h. The tensile properties at room temperature and 650 ℃ of specimens after HIP and HT are higher than those of the standard requirements for the forgings, and the temperature has a little influence on the fracture mode.

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    Fatigue property and fracture analysis on cold-expanded hole structure of GH4169 alloy
    Xin WANG, Xing CHEN, Ren-gao HU, Bo HU, Chun-ling XU, Zhi-hui TANG, Yuan-xing GU
    2020, 48 (6): 156-162.   DOI: 10.11868/j.issn.1001-4381.2018.001058
    Abstract ( 523 ( PDF (2754KB)( 229 Citation

    Cold expansion (CE) was applied on the centre-hole plate of GH4169 alloy. The fatigue lives, as received and after CE, were investigated at 825 MPa/600 ℃/R=0.1. Surface roughness before and after CE, residual stress profiles during fatigue cycles were studied. And the influence of surface integrity on fatigue process was analyzed by the careful fracture observation with two CE samples of different lives (25105 cycles and 10719 cycles). The results show that the median fatigue life estimation of specimens after CE doubles compared with as-received. The lower surface average roughness after CE and the stable residual stress profile during fatigue process are the main reasons for fatigue life promotion. However, the standard deviation of fatigue lives increases after CE. The fractographic quantitative analysis shows the propagation lives of two specimens beyond 0.1 mm from fatigue source are considered, but initiation lives (18786 cycles and 5915 cycles, respectively) are of great difference. As a contrast, the reason of the big dispersion about CE fatigue lives is the different initiation life within 0.1 mm from the source. Therefore, the attention should be paid to the surface integrity control of near surface during cold expansion to improve the stability of hole structure fatigue property.

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    Fei's square wave regulation on composition and amorphization of Ni-P alloy coating
    Qi-qi GUO, Jing-yin FEI, Man ZHANG, Xi-zheng HAN, Li-na ZHAO
    2020, 48 (6): 163-169.   DOI: 10.11868/j.issn.1001-4381.2018.001110
    Abstract ( 515 ( PDF (2441KB)( 170 Citation

    In order to solve the problem that the Ni-P alloy coating with an amorphous structure having excellent corrosion resistance cannot be obtained in the conventional electrodeposition process, Ni-P alloy coatings were prepared on the basis of a high-speed electroplating bath, and the law of influence of waveform parameters on the amorphization process of Ni-P alloy coatings was studied by using Fei's square wave electrodeposition method. The micromorphologies of Ni-P alloy coatings were characterized by scanning electron microscopy (SEM) under different conditions. The P content of the coatings was analyzed by energy spectrum analysis (EDS). Structural changes of phase of the coatings were investigated by X-ray diffraction (XRD). The optimized pulse process parameters are: the average current density is 15 A/dm2, the inverse pulse coefficient is 0.3, the duty ratio is 0.6, and the frequency is 1 Hz. The results show that by adjusting Fei's square wave pulse parameters, the fully amorphous Ni-P alloy coating can be electrodeposited, which has the features of high P content up to 17.93% (mass fraction), negligible nickel crystal diffraction peaks, and the smooth surface with a bright appearance as well.

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    Effect of heat treatment on microstructure and mechanical properties of FeCrMnNiCox alloy
    He-qi LI, Xiao-min WANG, Hong-yan ZENG
    2020, 48 (6): 170-175.   DOI: 10.11868/j.issn.1001-4381.2019.000647
    Abstract ( 569 ( PDF (2067KB)( 217 Citation

    FeCrMnNiCo, FeCrMnNiCo0.5 and FeCrMnNi alloys were prepared by vacuum melting and casting technology after metal powders was mixed by planetary ball mill. The effects of heat treatment temperature on the microstructures, tensile properties and hardness of three kinds of multi-principal alloys were studied by means of metallographic microscope, scanning electron microscopy (SEM), hardness tester and universal tensile testing machine. The results show that the hardness of FeCrMnNi alloy after heat treatment at 900 ℃ is the highest and the maximum hardness is 380HV. The plasticity of FeCrMnNiCo0.5 alloy is the largest after heat treatment at 700 ℃, and its elongation after fracture is 54.7%. At the same heat treatment temperature, with the increase of Co content, the alloys' structure is changed from dendritic to honeycomb, and the alloys' tensile strength is decreased. The hardness of the same alloy is increased with the increase of heat treatment temperature, which may be related to the increase of precipitates after heat treatment, but its tensile strength remains unchanged.

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