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  • 2007 Volume 0 Issue 9
    Published: 20 September 2007
      

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  • LI Xing-wu, SHA Ai-xue, CHU Jun-peng, ZHANG Lei, LU Min-xu
    2007, 0(9): 3-8.
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    LI Xing-wu, SHA Ai-xue, CHU Jun-peng, ZHANG Lei, LU Min-xu. Effect of Quenching Temperature on Deformation-induced Martensite of Ti-3Al-4.5V-5Mo Titanium Alloy[J]. Journal of Materials Engineering, 2007, 0(9): 3-8.

    Effect of quenching temperature on deformation-induced martensite of Ti-3Al-4.5V-5Mo titanium alloy was investigated by testing tensile stress-strain curves at different quenching temperatures and XRD patterns of uniform deformation areas of the fracture tensile samples.The result shows that the tensile deformation mechanism of the alloy quenching at 750-790℃ is deformation-induced martensite of metastable β phase,which is nearly fully transformed to α″ martensite at 6.5% deformation degree in the alloy quenching at 790℃.Stress assisted martensite is formed through βcubic→ α″σ by drawing the tensile samples quenching at 790℃ while strain-induced martensite is obtained through βcubic→βtetragonal→ α″ε quenching at 750℃.Reorientation of deformation-induced α″ martensite occurs during tensile deformation: [010]α″ direction parallel with tensile axis while [100]α″ direction perpendicular to tensile axis.
  • NING Bao-qun, LIU Yong-chang, QIAO Zhi-xia, YANG Liu-shuan
    2007, 0(9): 9-13,22.
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    NING Bao-qun, LIU Yong-chang, QIAO Zhi-xia, YANG Liu-shuan. Determination of Critical Cooling Rates in Undercooled Austenite Transformation Process of T91 Ferritic Heat-resistant Steel[J]. Journal of Materials Engineering, 2007, 0(9): 9-13,22.

    The critical cooling rates in undercooled austenite transformation process of T91 ferritic heat-resistant steel were studied by DIL805A/D high-resolution differential dilatometer.According to the dilatometric measurements,phase transformation kinetic information was obtained with the aid of the analysis of the lever rule from the recorded dilatometric curves.The microstructures of the T91 steel were adopted to determine the corresponding critical cooling rates.The results show that 10K/min is the upper limit for the formation of lath martensite,instead of ferrite appearing at 9K/min.Hence 10K/min could be regarded as the upper critical cooling rate of Ms transformation of T91 steel.In the range of 3-9K/min,the microstructure of the transformed steel is a mixture of the martensite and ferrite.Martensite disappears at 2K/min,and the corresponding structure is full ferrite,which suggests that 2K/min could be regarded as the lower critical cooling rate of Ms transformation of T91 steel.
  • HE Zi-qiang, WANG Xin-lin, QUAN Bai-yun, ZHAO Zhen-ye, LI Zhi
    2007, 0(9): 14-17,29.
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    HE Zi-qiang, WANG Xin-lin, QUAN Bai-yun, ZHAO Zhen-ye, LI Zhi. Glass Forming Ability and Thermal Stability of (Fe0.5Ni0.5)80-xMoxB20 Amorphous Alloys[J]. Journal of Materials Engineering, 2007, 0(9): 14-17,29.

    Glass forming ability and thermal stability of (Fe0.5Ni0.5)80-xMoxB20(x=0,2,4,6,8) amorphous alloys were studied by XRD,TEM and DSC.Furthermore,the expression of glass forming ability and the effects of Mo addition on glass formation and thermal stability of (Fe0.5Ni0.5)80-xMoxB20 amorphous alloys were discussed.The results show that the addition of Mo in (Fe0.5Ni0.5)80-xMoxB20 alloy causes improvement in glass forming ability and thermal stability,which is ascribed to the increase of both the components number and the difference in atomic size of components,and the negative heats of mixing.Tx/Tm is reasonable for indicating the glass forming ability of (Fe0.5Ni0.5)80-xMoxB20 amorphous alloys.
  • ZHANG Guo-xiang, CHEN Guang-nan, LI Huai-xue, ZHANG Kun, LUO Geng-xing
    2007, 0(9): 18-22.
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    ZHANG Guo-xiang, CHEN Guang-nan, LI Huai-xue, ZHANG Kun, LUO Geng-xing. Effect of Laser-quenching Substrate on Resistance Contact Distortion of Cr-plated Coatings[J]. Journal of Materials Engineering, 2007, 0(9): 18-22.

    The duplex technology that the substrate was discretely quenched by laser before chromium-plating was presented.The simulated experiment of contact load into Cr-coating surface was carried along the vertical direction of laser scanning by the scratch device.The experimental result shows that the capacity of resistance contact distortion of Cr-plated coatings increases with the help of laser quenching substrate.The free-standing Cr-coating was prepared by the method of chemically etching substrate.The mechanical properties of initial Cr-plating coating ware measured by nano-indentation through the indenter pressing on the interface of Cr-coating.The comparative result shows that the capacity of resistance contact distortion of Cr-plated coatings is improved by the increase of not only the substrate hardness but also the self-resistance capacity of Cr-coating through laser quenching substrate.
  • MA Wen-shi, DONG An-hui
    2007, 0(9): 23-25.
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    MA Wen-shi, DONG An-hui. Nano-AlN Powder Doubly Modified by KH570 and Polystyrene[J]. Journal of Materials Engineering, 2007, 0(9): 23-25.

    Inorganic nano-AlN powder doubly modified by KH570 and polystyrene was prepared.The nano-AlN powder before and after being modified was characterized by FTIR,TG/DTG and XRD.The results showed that some polystyrene(PS) chains were bonded to the nano-AlN particles surface through the silicane coupling agent KH570.The temperature of maximum mass loss rate of nano-AlN powder rose from 202.3℃ before being modified to 228.07℃.While the mass fraction of modified agents was about 2%-3% of nano-AlN powder,the modified effects were good.Hydrolysis didn’t take place when nano-AlN powder was immersed in water at 70℃ for 24h.The hydrophobic property and anti-hydrolytic property of nano-AlN powder were improved obviously.
  • YUAN Shen-po, LI Shu-kui, SONG Xiu-gang, CHENG Xing-wang, WU Fu-yao
    2007, 0(9): 26-29.
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    YUAN Shen-po, LI Shu-kui, SONG Xiu-gang, CHENG Xing-wang, WU Fu-yao. Fragile Tungsten Alloys Made of W-Ni-Al-Fe[J]. Journal of Materials Engineering, 2007, 0(9): 26-29.

    A fragile penetrator material made of W-Ni-Al-Fe was studied.The material was made by CIP and sintering process.Al2O3 was found in the matrix of the materials through metallographic testing and SEM analysis,which reduced the tensile strength.All of this improved the fragmentation of penetrator.The dynamic compressive strength of the new type materials was the same as 93W-Ni-Fe alloys,but the tensile strength reduced about 200MPa and the extension rates reduced 20%.
  • LIU Xue-feng, RONG Ming-lei, MA Sheng-jun, XIE Jian-xin
    2007, 0(9): 30-33.
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    LIU Xue-feng, RONG Ming-lei, MA Sheng-jun, XIE Jian-xin. Preparation of Pure Copper Plates with Continuous Columnar Crystals[J]. Journal of Materials Engineering, 2007, 0(9): 30-33.

    Pure copper plates were prepared by vacuum melting and argon-shield vertical continuous unidirectional solidification process.The effects of process parameters on the solidification forming were investigated,and microstructure and properties of the fabricated plates were analyzed.The results showed that pure copper plates of 25mm in width and 5mm in thickness with luminant surface and columnar crystals can be continuously and stably fabricated under the conditions of melting temperature 1160℃,drawing speed 70mm/min,cooling water volume 900L/h.The pure copper plates with the tensile strength 146MPa,yield strength 33MPa,elongation 54% and conductivity 105.9% IACS showed an excellent mechanical and conductive properties.
  • ZHANG Bao-fa, JIANG Hai, LI Dong-sheng
    2007, 0(9): 34-36.
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    ZHANG Bao-fa, JIANG Hai, LI Dong-sheng. Influence of Chemical Vapor Deposited Carbon on Oxidation Property of Graphite Materials[J]. Journal of Materials Engineering, 2007, 0(9): 34-36.

    The influence of chemical vapor deposited carbon on the oxidation property of graphite was investigated.The results show that the chemical vapor deposited carbon can apparently improve the oxidation property of fine grain graphite,especially for high temperature deposition.But the chemical vapor deposition has little influence on the oxidation property for the coarse grain graphite.The fine grain graphite is oxidized from the surface and propagates gradually to the inner.For the coarse grain graphite,oxidization occurs in the boundary zones.Although the mass loss during oxidation is very small,the deep inner boundary can be oxidized easily.
  • LIU Jun, PENG Chao-yi, DU Gang, ZENG Jing-cheng, XIAO Jia-yu
    2007, 0(9): 37-41.
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    LIU Jun, PENG Chao-yi, DU Gang, ZENG Jing-cheng, XIAO Jia-yu. Fabricating Carbon/Epoxy Primary-load Bearing Cylinders by Thermal Expansion Mould Method[J]. Journal of Materials Engineering, 2007, 0(9): 37-41.

    The process principle of thermal expansion mould method(TEMM) was illustrated and the key process procedure was further studied.TEMM was utilized to fabricate the carbon/epoxy cylinders that were expected to serve in a large-load bearing thrust structure in the space delivery vehicle.Compared with wound cylinders which fabricated with the same materials and the same size,the axial compressive strength of the TEMM cylinders was much higher than that of the traditional wound cylinders.The micro appearance analysis also indicates that the solidity of TEMM cylinders is better than that of the wound cylinders.
  • XU Zheng-fang, XU Xiang-jun, LIN Jun-pin, ZHANG Yong, WANG Yan-li, LIN Zhi, CHEN Guo-liang
    2007, 0(9): 42-46.
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    XU Zheng-fang, XU Xiang-jun, LIN Jun-pin, ZHANG Yong, WANG Yan-li, LIN Zhi, CHEN Guo-liang. Elimination of β Phase Segregation in As-cast High Nb Containing TiAl Alloy by Heat Treatment[J]. Journal of Materials Engineering, 2007, 0(9): 42-46.

    The effect of the heat treatment on the elimination of the β phase segregation in as-cast high Nb containing TiAl alloy on large scale was studied.The results show that the β phase segregation can be eliminated by holding appropriate time in the two phase region of α+γ.The β-segregation at the grain boundaries and α-segregation in lamellar colonies can be efficiently eliminated after 1250℃/24h + 900℃/30min /AC for the alloy samples;but after 1280℃/6h+900℃/30min/AC,the volume fraction of β phase is very small and completely eliminated after holding 12h at the cost of the average lamellar colony size coarse from 75μm to 123μm.
  • WANG Xiu-fei, HUANG Qi-zhong, SU Zhe-an, YANG Xin, WU Cai-cheng, NING Ke-yan
    2007, 0(9): 47-50.
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    WANG Xiu-fei, HUANG Qi-zhong, SU Zhe-an, YANG Xin, WU Cai-cheng, NING Ke-yan. Effects of Si Content on Mechanical Properties of C/C-SiC Composites[J]. Journal of Materials Engineering, 2007, 0(9): 47-50.

    Carbon fiber reinforced silicon carbide composites were fabricated by warm compaction-in situ reaction process.The effects of Si content on the structure and properties of C/C-SiC were investigated.The results showed that with the increase of silicon,the density and the graphitization degree of the C/C-SiC composites gradually increased while the relative density was getting decreased and the flexural strength was lowered.But the shear strength had no obvious changes.After siliconizing at 2100℃,the graphitization degree of the C/C-SiC materials increased from 21.7% to 45.2% when silicon added up from zero to 35%(mass fraction).Silicon carbide was formed and distributed along the carbon fiber when Si reacted with carbon fiber and resin carbon.All Si was changed into SiC in the composite.When Si was over 30%(mass fraction),there were some carbon riched SiC particles around carbon fiber.
  • CHENG Ju-qiang
    2007, 0(9): 51-54.
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    CHENG Ju-qiang. Joint Microstructure and Properties at Various Welding Method in High Strength Bainitic Steel Plate[J]. Journal of Materials Engineering, 2007, 0(9): 51-54.

    The joint microstructure and mechanical properties of high strength bainitic steel plate were studied by CO2 gas shielded welding(CGSW),submerged arc welding(SAW) and manual arc welding(MAW).The results show that welding and without heat treatment,the microstructure of CGSW is bainite,a little ferrite and pearlite,there is new type bainitic microstructure in heat-affected zone.The microstructure of weld metal for MAW is blocky ferrite and a little pearlite,the microstructure in the heat-affected zone is new type bainite.The microstructure of weld metal for SAW is acicular ferrite,and there is new type bainitic microstructure in heat-affected zone,grains are well-distributed and good joining in bond area.The weld joint of bainitic steel plate has good strength and toughness after various welding.
  • SUN De-ming, ZHANG Qin-he, CHAI Qi, ZHANG Ming-qin, XU Chong-hai
    2007, 0(9): 55-57,61.
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    SUN De-ming, ZHANG Qin-he, CHAI Qi, ZHANG Ming-qin, XU Chong-hai. Analysis of Chemical Compatibility of Al2O3/Cr3C2/(W,Ti)C Composites[J]. Journal of Materials Engineering, 2007, 0(9): 55-57,61.

    Based on the theory of thermal-dynamics,the chemical compatibility of the possible composition system of ceramic material Al2O3/Cr3C2/(W,Ti)C was analyzed.The results show that no chemical reaction could take place under 1800℃ through Cr3C2,(W,Ti)C and Al2O3.And it was tested by the fabrication of the Al2O3/Cr3C2/(W,Ti)C composite with the hot pressing sintering technique.
  • LIU Hui-min, Hunusitu, YOU Guo-yan
    2007, 0(9): 58-61.
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    LIU Hui-min, Hunusitu, YOU Guo-yan. Plastic Deformation Mechanism of In-situ Reactive Spray Formed 7075 Al Alloy[J]. Journal of Materials Engineering, 2007, 0(9): 58-61.

    The plastic deformation behavior of in-situ reactive spray formed 7075 Al alloy during hot compression deformation was studied by isothermal compression test at Gleeble-1500 thermal-mechanical simulator.The dynamic recrystallization mechanism during hot compress was examined using SEM and the true stress-strain curves.The results show that the flow stress decreases with the increase of deforming temperature,dynamic recrystallization occurs at 400℃ of deforming temperature.When the deformation temperature increases to 450℃,the balance is remained between hardening and softening during hot compression deformation.
  • BO Lan, WANG Sheng-jie, KONG Jie
    2007, 0(9): 62-66.
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    BO Lan, WANG Sheng-jie, KONG Jie. UV Curing Behavior and Thermodegradation Mechanism of Polysiloxanes[J]. Journal of Materials Engineering, 2007, 0(9): 62-66.

    Polysiloxanes with different vinyl contents were synthesized via polycondensation reaction,and characterized by FT-IR and GPC.The effects of photoinitiator,atmosphere,and contents of vinyl groups on UV curing behavior of polysiloxanes were explored,according to the absorption area changing of double bond in FT-IR spectra under UV radiation.Finally,TGA was used to investigate their thermodegradation mechanism.Experiment results indicated that curing rate and thermal stability of the polysiloxanes were improved with the increasing of methylvinylsiloxane units in polysiloxanes with IHT-PI-185 as photoinitiator in nitrogen atmosphere.
  • NING Jun-sheng, FAN Ya-fu, PENG Xiu-feng
    2007, 0(9): 67-73,80.
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    NING Jun-sheng, FAN Ya-fu, PENG Xiu-feng. Research and Progress of Plastic Deformation of Magnesium Alloys at High Strain Rate and Large Deformation[J]. Journal of Materials Engineering, 2007, 0(9): 67-73,80.

    Study about micro-structural changes of magnesium alloys under large strains and severe plastic deformation were introduced.Attention is concentrated on the research about the plastic deformation of magnesium alloys under impact loading and high strain rate.Meanwhile,the properties and physical mechanisms of plastic deformation of magnesium alloys under different loads and over a wide range of temperatures were reviewed.Finally,several formula for describing the behaviors of magnesium alloys under dynamic loading at high strain rate was summarized briefly,and some suggestions on the study of magnesium alloys used as structural materials were offered.
  • GUO Jian-wei, HUANG Yang-hai, LIU Sa, DENG Zhi-cheng, YU Lin
    2007, 0(9): 74-80.
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    GUO Jian-wei, HUANG Yang-hai, LIU Sa, DENG Zhi-cheng, YU Lin. Development of Ordered-mesoporous Metal Oxides[J]. Journal of Materials Engineering, 2007, 0(9): 74-80.

    This paper mainly deals with three synthesis pathways of ordered-mesoporous metal oxides,including the charge density matching approach,neutral template approach and ligand-assisted template approach.Then the synthesis mechanism,researching status of some ordered-mesoporous metal oxides,such as ordered-mesoporous Al,Zr,Ti,Mn,Nb metal oxides etc,and their applications are reviewed as well.Finally,the developing direction of ordered-mesoporous metal oxides in the future is pointed out.
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