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  • 2001 Volume 0 Issue 7
    Published: 20 July 2001
      

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  • ZHENG Yunrong, MA Shuwei, ZHANG Jun, HUANG Weidong, FU Hengzhi
    2001, 0(7): 3-6.
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    ZHENG Yunrong, MA Shuwei, ZHANG Jun, HUANG Weidong, FU Hengzhi. Solidification Behavior of Ni3Al/Ni7Hf2 Directionally Solidified Eutectic Alloys[J]. Journal of Materials Engineering, 2001, 0(7): 3-6.

    Microstructure,and solidification behavior of Ni3Al/Ni7Hf2composites were investigated The results show that the Ni-5.8Al-32Hf and Ni-4Al-26Hf-8Cr-4W alloys are suitable composition for directionally solidified eutectic composites Ni3Al and Ni7Hf2 phases exist in as cast alloy, but small amount of β NiAl phases appears in the slowly solidified alloys. The solidified temperature ranges of the ternary alloy and the quinary alloys are 41℃ and 57℃ respectively The critical ratio of G/R is found to be 5×105and 7×106℃·s·cm-2.The lamellar Ni3Al/Ni7Hf2 eutectic aligned parallel to the direction of solidification was prepared with G=250℃ cm-1and R=5μm·s-1for the ternary alloy, and G=350℃cm-1 and R=1μm·s-1of the quinary alloy.
  • YANG fubao, GUO Jianting, ZHOU Jiyang
    2001, 0(7): 7-10.
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    YANG fubao, GUO Jianting, ZHOU Jiyang. Mechanically Synthesis and Mechanical Properties of Nanocrystalline NiAl Matrix Composite Reinforced by HfC Particles[J]. Journal of Materials Engineering, 2001, 0(7): 7-10.

    WT5BZ]Reactive milling elemental mixed powders have been used to synthesize NiAl-HfC composite The formation mechanism can be attributed to two explosive reaction, Ni+Al→NiAl+△H;Hf+C→HfC+△H,aroused by mechanical collision After densification by hot pressing and isostatically pressing,its microstructure and mechanical properties have been investigated The results show that the reinforced HfC particles size is below 100nm, and coarse ones(50~100nm)are distributed mainly in grain boundaries of matrix The yield strength of NiAl 10HfC composite is significantly stronger than that of NiAl Furthermore, it also possesses good compressive ductility.The yield strength of NiAl 10HfC composite at high temperature is dependent on strain rate,and deformation is controlled by diffusion mechanism.
  • WEI Zunjie, WANG Hongwei, ZHANG Erlin, ZENG Songyan
    2001, 0(7): 11-14.
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    WEI Zunjie, WANG Hongwei, ZHANG Erlin, ZENG Songyan. Effect of Carbon Content on Microstructure of As-Cast Ti-11Al Alloy[J]. Journal of Materials Engineering, 2001, 0(7): 11-14.

    Particulate reinforced Ti-11Al matrix composites with different C content were fabricated by using a reaction synthesis method Microstructures of the composite were investigated by XRD,OM and SEM The results indicate that the matrix of alloy is transformed to single α2 phase from α+α2 two phases, and reinforcements become Ti3AlC and TiC two phases from single TiC phase as C content increasing to a critical value Also with the increasing of C content, the morphology of reinforcements are changed from short lath shape to undeveloped dendrite and equiaxed dendrite In the meantime, the main reasons of microstructure transformation were analyzed in the light of phase diagrams.
  • QI Yihui, GUO Jianting, CUI Chuanyong, LI Gusong
    2001, 0(7): 15-18.
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    QI Yihui, GUO Jianting, CUI Chuanyong, LI Gusong. Influence of Hot Isostatic Pressing on Microstructure and Properties of NiAl-Cr(Zr) Intermetallic Alloy[J]. Journal of Materials Engineering, 2001, 0(7): 15-18.

    The microstructure and high temperature mechanical properties of as cast and HIP ed multiphase NiAl-33.5Cr-0.5Zr intermetallic alloy were investigated The results indicates that the magnitude of the eutectic cell of the HIP edalloy is at least the same as as cast, but α Cr phase turn out coarser and longer,the Ni2AlZr phase at the cell boundary is converted to Zr rich phase After HIP-ed, the compressive yield stress is significantly increased When the strain rate is 1.04×10-3 s-1at 1273K, the compressive yield stress has an approximate 50% increase and when the strain rate is 1.04×10-4 s-1 and 5×10-5s-1 at 1273K, the compressive yield stress has an approximate 100% increase The curves of the true compressive stress true strain between as cast and HIP ed alloy at low strain rate are significant different.The behavior of high temperature deformation is fitted successfully by power law and temperature compensated power law TEM observation indicates that the high temperature deformation mechanism is controlled by subgrain formation.
  • YANG Shengliang, ZHUO Yue, YIN Xinfang, YANG Deming
    2001, 0(7): 19-21.
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    YANG Shengliang, ZHUO Yue, YIN Xinfang, YANG Deming. The Interfacial Microstructure of CF/Al Composites[J]. Journal of Materials Engineering, 2001, 0(7): 19-21.

    The interfacial reaction characteristics of CF/Al composite wires with a diameter of 0.5mm fabricated by ultrasonic aid liquid infiltration method and composite plates made by vacuum high pressure liquid infiltration process were studied via transition electron microscope (TEM) Two types of carbon fiber, T300 and M40J, are used as reinforcement.The TEM results show that the interfacial reactant is needle like Al4C3.However,the interfacial reaction of both types of fiber is relative slight and there exits obvious difference in the magnitude of Al4C3 between two types of carbon fiber.The length of Al4C3 is about 200~400nm in T300/Al wire and 100~200nm in M40J/Al.The results indicate that the reactivity of high strength type carbon fiber T300 with the liquid aluminum is higher than that of the high modulus type graphite fiber M40J.It is realized that the difference in reactivity should result from the microstructure difference between two types of fiber, that is the high graphitization degree of M40J fiber retards the diffusion of carbon atom.The interfacial reaction of CF/Al composite plates is found to be very slight and little reaction can be found in the interface.This results should be related to the fabrication process, that is the short infiltration time under high pressure and high cooling speed of composites minimize the contact time of fiber with matrix at high temperature and leads to the slight interfacial reaction.
  • LUO Fa, ZHOU Wancheng
    2001, 0(7): 22-24.
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    LUO Fa, ZHOU Wancheng. Preparation and Properties of Si2ON2/LAS Nanocomposite[J]. Journal of Materials Engineering, 2001, 0(7): 22-24.

    Preparetion and properties of Si2ON2/LAS nano-composite were investigated.The results show that the Si2ON2/LAS nano-composite can be formed from nanoβ-Si3N4and LAS glass powder in hot pressing conditions.The nano-Si2ON2in the composite is club-like.The optimum content of nano Si2ON2 is 20 wt%.Compared with pure LAS glass-ceramic, the strength and fracture toughness of the composite are increased by a factor of 31% and 88%, respectively.The strength and fracture toughness are decreased rapidly when the amount of nano Si2ON2 is over 20wt%.This decrease is caused by the decrease in the density of the composite.
  • WANG Rongming, LI Chunzhi, YAN Minggao
    2001, 0(7): 25-28.
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    WANG Rongming, LI Chunzhi, YAN Minggao. Micro-mechanism Study on the Properties Affects in a Low Expansion Superalloy GH907 with Addition of RE Elements[J]. Journal of Materials Engineering, 2001, 0(7): 25-28.

    The affective rule of the mechanical and physical properties in Fe-Ni-Co-Nb-Ti-Silow expansion superalloys with addition of RE elements has been studied.The alloy system with good notch-bar rupture strength and oxidation resistance at high temperatures has been selected and investigated.The micro-mechanism of the properties improvement has also been proposed by comparison of the microstructures and interface structures of the alloys with and without yttrium addition.The results reveal that the rare earth element exists in the platelet phase and changes the content, morphology, distribution and crystal structure of the phase.The crystal misfit and stress at the interface between the platelet phase and the matrix decrease significantly.
  • YANG Lei, PAN Qinglin, YIN Zhimin, WU Jiansheng
    2001, 0(7): 29-32.
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    YANG Lei, PAN Qinglin, YIN Zhimin, WU Jiansheng. Effects of Minor Sc and Zr on Microstructure and Properties of Al-Zn-Mg Alloy[J]. Journal of Materials Engineering, 2001, 0(7): 29-32.

    The Al-Zn-Mg-Sc-Zr alloy was prepared by ingot-metallurgy processing.The tensile mechanical properties of the studied alloys at different treatments were tested and the microstructure and mechanical properties of the alloy was studied by using optical microscope and transmission microscope.The results show that the minor Sc and Zr can greatly fine the grain size of the Al-Zn-Mg alloy ingots. Minor Sc and Zr can remarkably improve the properties of the Al-Zn-Mg alloys. The strengthening mechanisms are considered as fine grain strengthening, substructure strengthening, and dispersion strengthening.
  • ZHU Liqun, WU jun, LIU feng, ZHANG Chungang
    2001, 0(7): 33-35.
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    ZHU Liqun, WU jun, LIU feng, ZHANG Chungang. Study of the Capability of the Electrocomposite Coating on the Cu-Zr Alloy[J]. Journal of Materials Engineering, 2001, 0(7): 33-35.

    Using the method of electrodeposition,the Ni-ZrO2 composite coating was deposited on the Cu-Zralloy substrate.The influence of the content of ZrO2 powder in the plating solution on the content of the coating was studied too.The high-temperature oxidation resistance law of the Ni-ZrO2 coating was studied.From the study result,The oxidation resistance of the Ni-ZrO2 composite coating is better than that of Ni coating.The corrosion resistance of the Ni-ZrO2 composite coating was also studied In the solution of 0.5mol/LHNO3,the corrosion resistance of the Ni-ZrO2 composite coating is better.
  • ZHU Yongfa, YIN Musheng, WANG Li, YAO Wenqing, JI Shishan, CAO Lili
    2001, 0(7): 36-39.
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    ZHU Yongfa, YIN Musheng, WANG Li, YAO Wenqing, JI Shishan, CAO Lili. A Study of Interface Diffusion and Reaction of Ti/ZrN2/Al Film[J]. Journal of Materials Engineering, 2001, 0(7): 36-39.

    ZrN2 and Ti multiplayer was deposited on aluminium using DC magnetron sputtering method.The interface diffusion and chemical states on interface were investigated using line shape analysis and depth profile analysis of Auger electron spectroscopy.The results show that the interface diffusion of Ti/ZrN2/Al is intensified by vacuum heat treatment.The interface reaction also is promoted by heat treatment and TiNx species are formed on the interface Serious oxidation takes place in the film.
  • ZHANG Jianguang, ZHANG Mingfu, HAN Jiecai, HE Xiaodong
    2001, 0(7): 40-42.
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    ZHANG Jianguang, ZHANG Mingfu, HAN Jiecai, HE Xiaodong. α-Fe2O3 Nanocrystallites Prepared by a Combustion Method[J]. Journal of Materials Engineering, 2001, 0(7): 40-42.

    Using hydrate ferric nitrate as starting materials and PVA as chelate agent,α-Fe2O3 nanocrystallites were successfully prepared by a combustion method without adjusting pH value of reaction system.The combustion products were analyzed and investigated by means of XRD,TEM and infrared spectroscope.The results show that the product of combustion reaction at 150℃ includes partial γ-Fe2O3 and α-Fe2O3.After calcining as-combusted product at 400℃ for 1.5h,the mixture of γ-Fe2O3 and α-Fe2O3 is obtained and organic components is decomposed completely.After calcination at 450℃ for 1.5h,γ-Fe2O3 is transformed to α-Fe2O3 entirely and spherical α-Fe2O3 particles are obtained.The diameter of spherical particles predicted from TEM photograph is 20nm to 35nm.The diameter of particles in the product of calcination at 500℃ is 25nm to 40nm and slightly bigger than the former.
  • TAN Jingshuang, ZHANG Baofa, JIANG Hai, LI Dongsheng
    2001, 0(7): 43-44.
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    TAN Jingshuang, ZHANG Baofa, JIANG Hai, LI Dongsheng. A Study on Structure and Fracture Morphologies of Carbon/Carbon Composite Brake Discs[J]. Journal of Materials Engineering, 2001, 0(7): 43-44.

    The preforms of several types of brake discs were investigated by a special corrosion method.The fracture morphologies of the brake discs in parallel and perpandicular faces were ob-served by scanning electron microscope.The interfacial characteristics between carbon fibers and the matrices were analyzed.
  • ZHU Hua, ZHANG Hongyan, YANG Xiren, ZHANG Juhua
    2001, 0(7): 45-46.
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    ZHU Hua, ZHANG Hongyan, YANG Xiren, ZHANG Juhua. Prediction for Service Life of Aeronautical Rubbers and Sealant by Computer Technique[J]. Journal of Materials Engineering, 2001, 0(7): 45-46.

    Based on Arrhenius equation and aging data which were acquired by air aging method, the experiential aging formula of rubber was calculated, and a software edited with VB language was created and used to predict service life of aeronautical rubbers and sealant.The service life of XM 22B sealant and 5880 rubber predicted by the software was very fitted with the experiment data.
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