LI Jie, SUN Feng, LI Chun-zhi, GUO Feng, LI Zhi, YAN Ming-gao. Analysis of Strengthening Precipitates of High Co-Ni Ultra-high Strength Steel[J]. Journal of Materials Engineering, 2009, 0(7): 1-4.
TEM was used to investigate the precipitates in ultra-high strength steel AerMet100 after overaging at 510℃,and the nature of these precipitates was identified by using SAD analysis.The results show that the precipitates are mainly consisted of two types of particles,one is the well-known rod-like M2C carbide with 17.5nm in length and 6nm in diameter,well aligned in the three normal directions which are parallel to the 〈001M family of directions of martensitic matrix,and the orientation relationship with martensitic matrix is(011)M//(001)M2C,[100]M//[100]M2C.The other kind of precipitate is ellipsoidal Fe2Mo intermetallic compound(Laves phase) with 11.5nm in diameter,and orientation relationship is(112)M//(001)L,[111]M//[100]L.Both of them are dispersed within the matrix of fine lath martensite and equivalent in size.
ZHOU Zhen-ni, HOU Ting-ping, ZHANG Guo-hong, ZHANG Jing-jing, WU Kai-ming. Carbide Precipitation in a Medium Carbon Low Alloy Steel Under a High Magnetic Field[J]. Journal of Materials Engineering, 2009, 0(7): 5-8.
The carbide precipitation in ferrite during ioothermal holding at 700℃ and 530℃ in a medium carbon low alloy steel was investigated under a 12 Tesla high magnetic field utilizing transmission electron microscopy(TEM).Results show that the sequence of carbide precipitation at 700℃ is not changed;and conversely the sequence of carbide precipitation at 530℃ is changed.
ZHU Yong-bing, MU Si-guo, LI Hua-qing, GUO Fu-an. Texture Analysis of Cu-Cr-Zr Alloy in Process of Deformation[J]. Journal of Materials Engineering, 2009, 0(7): 9-11,38.
The Cu-Cr-Zr alloy was treated by hot rolling,solution and cold rolling.The types and the evolution of texture in the different state were investigated using X-ray diffraction.The results show that the main textures of the alloy after hot rolling are Copper{112}〈111〉(C),Brass{011}〈211〉(B) and S{123}〈634〉 texture,including the faint cube{001}〈100〉 texture.The intensity of the texture decreases after solution and the cube texture disappears.In the condition of cold rolling,the intensity of texture enhances with the increasing of the deformation.The main textures during the cold rolling are C,B and S texture.In the early stage of the cold rolling,it appears the Goss{011}〈100〉(G) texture,then weakening gradually until disappears.
LI Hong-yu, SONG Xi-ping, WANG Yan-li, CHEN Guo-liang. Dependence of Composition of γ'/γ Phases on Aging Time and Temperature in Superalloy GH742[J]. Journal of Materials Engineering, 2009, 0(7): 12-15,22.
The phase composition of γ’phase and γ matrix in GH742 was investigated by energy dispersive of X-ray spectroscopy(EDX) in an analysis transmission electron microscope(TEM-EDX).The dependence of composition of γ' and γ phase on aging time indicates that the composition of γ' and γ phase evolves drastically in short aging time at the temperature of 1050℃ and reaches the equilibrium condition when aging for 1440 min.The dependence of composition of γ' and γ phase on temperature indicates that the composition of γ' and γ phases evolves with the increasing temperature in the range of 750℃ to 1100℃.The dependence of partitioning ratios Cγ'/Cγon temperature shows that the partitioning ratios Cγ'/Cγ of γ'-forming elements Ti,Al,Nb,Ni have a decrease and those of γ-forming elements Cr,Co,Mo have an increase with the temperature increasing.
XIE Chong-bo, XU Yong-dong, WANG Yi, ZHANG Li-tong, CHENG Lai-fei, WANG Yi-guang, TONG Chang-qing. Preparing of 3D C/SiC-TaC Composites Using Slurry and CVI Method and Research on Anti-ablation Property[J]. Journal of Materials Engineering, 2009, 0(7): 16-22.
Using a kind of slurry which contains 1μm TaC fillers 4%(volume fraction) to introduce TaC fillers into 10mm thick 3D carbon fiber perform,three kind of TaC content(low,medium,high) preforms were obtained.3D C/SiC-TaC composites were prepared after densification using CVI SiC.The resultant and microstructure were studied using XRD and SEM after oxygen-acetylene flame test.The results showed that this joint method could prepare C/SiC-TaC composites,the high content TaC fillers were oxided into TaC and Ta2O5 which were a solid and liquid mixture,this mixture could effectively cover the ablation surface and promote anti-ablation poperty.
YAO Jian-sheng, LI Zhi-hong, TANG Ding-zhong, LIU Xiao-guang, XIAO Ke. Effect of Particle Size of Al2O3 Powder on Property of Silica Sol Slurry and Ceramic Shell[J]. Journal of Materials Engineering, 2009, 0(7): 23-27.
The Al2O3 powders of three different particle sizes were used to confect the slurry.The rheological properties of slurry and mechanical properties of ceramic shell were investigated,and the gravitational distortion of shell at high temperature was also investigated.The advantage and disadvantage of three kinds of Al2O3 powders were tested through the disquisition of actual casting instance.The experiment results indicated that the rheological properties of three slurries were all favorite,and better comprehensive properties were possessed to the shell made by W20+W40 powder.Its bending strength at 1500℃ was up to 1.14MPa,and its gravitational distortion reduced to 2.98%.The statistical results of actual casting condition suggested that this kind of casting had favorable technological property which had smooth surface and had no sand burning and seam.
GE Qi, ZHANG Jun-ying, WANG Tian-min, XIAO Shi-tang. Application of Taguchi Methods in the Preparation Techniques of Light-storing Ceramics[J]. Journal of Materials Engineering, 2009, 0(7): 28-31.
The advanced quality management theory "Taguchi Methods" was applied to the preparation techniques of light-storing ceramics,a new kind of architectural decorative material,and further to the optimization design and quality control in order to acquire the higher stable process.The fluctuation around the average value was controlled by the ceramics glaze and the manufacture mode of the surface glaze,and at the same time,the appropriate choices for other factors would reduce the cost of product.The effectiveness of the "Taguchi Methods" was tested.
WANG Fu, WANG Qiang, CAO Wen-bin, SUN Jia-lin. Microwave Synthesis of SiC Powders with Coke and Quartzite[J]. Journal of Materials Engineering, 2009, 0(7): 32-35.
SiC powders were synthesized through the reaction between coke and quartzite by microwave heating.The results show that full conversion can be achieved at 1600℃ for holding 30min and the content of SiC in the reacted powders is higher than 98%.SiC powders were synthesized from coke powders with diameters of ～2μm,5-20μm,100-200μm,which have similar particle size with the starting coke particles.The microwave-assisted synthesis is fast and economical,and can significantly promote the reaction.
QIN Xin, ZHANG Yan-hua, XIONG Lin-yu. Experimental Investigation on Fatigue Crack Growth in GH4169 Superalloy at High Temperature[J]. Journal of Materials Engineering, 2009, 0(7): 36-38.
The experimental study on fatigue crack growth of GH4169 superalloy has been carried out.The temperatures of fatigue crack growth tests was 650℃.The results show that the fatigue crack growth rate,initial crack length,critical crack and temperature all have an effect on fatigue crack growth of GH4169.The fatigue crack growth and critical crack of base metal and joints also have great difference.
DAI Yong-juan, TAND Di, MI Zhen-li, JIANG Hai-tao, LU Jian-chong. The Influence of Manganese on the Stacking Fault Energy and Deformation Mechanisms of the TWIP Steel[J]. Journal of Materials Engineering, 2009, 0(7): 39-42.
The stacking fault energy of the Fe-XMn-3Si-3Al system alloys was calculated according to the thermodynamic model of stacking fault energy.The calculated results showed that the stacking fault energy of Fe-XMn-3Si-3Al system alloys increased with increasing manganese content.The influence of Manganese content on the deformation mechanisms,mechanical properties and microstructure of Fe-XMn-3Si-3Al system alloys was discussed based on above results.With the increasing of manganese content,the Fe-XMn-3Si-3Al system alloys show different deformation mechanisms from the TRIP effect turns to the TWIP effect.At the same time,the strength decreasing and the elongation increasing.
LI Guang-zhu, SHEN Yan-xia, ZHAN Mao-sheng. Study on Performance of Thermal Insulation of Aromatic Polyimide Foams[J]. Journal of Materials Engineering, 2009, 0(7): 43-46.
Experimental studies were undertaken to investigate glass transition temperature,thermal conductivity at static temperature and performance of thermal insulation at dynamic temperature of 4 kinds for aromatic polyimide foams by DMTA and self-made apparatus.The relationship of density,temperature between thermal conductivity of polyimide foams and performance of thermal insulation of polyimide foams at dynamic temperature were examined.The results show that stiffness of monomer(especially diamine) has influence on glass transition temperature of polyimide foams;the density of polyimide foams ranging from 50-140kg/m3has little influence on thermal conductivity;with static temperature ranging from 50-350℃ rising,thermal conductivity of polyimide foams are also rising;at dynamic temperature,polyimide foams show hysteretic nature obviously.
LIU Wei, GAO Zong-zhan, LIU Yong-shou, YUE Zhu-feng. Experimental Study of Creep Behaviors of MDYB-3 PMMA Under Different Temperatures[J]. Journal of Materials Engineering, 2009, 0(7): 47-49,82.
Creep behaviors of aeronautic Polymethyl Methacrylate(MDYB-3 PMMA) under different temperatures were experimentally investigated.The creep curves of PMMA at 20℃,50℃ and 75℃ and with various stresses were obtained.It was indicated that the duration curves of creep could be divided into three phases.Experimental results showed that the steady creep accumulation speed was increasing with the temperature and stress increasing,and the rupture stretch was increasing accordingly,but the failure time was reducing.The Chen theory,Norton formula and exponential expression were used to describe three phases of creep behaviors respectively.
GE He-yi, LIU Hua-shi, CHEN Juan. Microstructure of PAN Precursor Fibers in Wet-spinning[J]. Journal of Materials Engineering, 2009, 0(7): 50-53.
The morphology and the structural interrelationship of PAN fibers in wet-spinning have been analyzed by the means of Scanning Electron Microscope(SEM) and Transmission Electron Microscopy(TEM).The results indicated that the structure of PAN precursor fibers was inherited from that of nascent fibers.PAN precursor fibers were composed of four parts.The sheet-like skin which had high crystallization and highly oriented structure was compact and homogeneous.The core which had low crystallization was loose and disorderly.Meanwhile,the precursor fibers had a pillar-like layered structure along the fiber axis.From the skin to the endothecium,the average thickness of each layer increased gradually.Furthermore,a structural model of PAN precursor fibers has been established.
DU Bo-xue, LIU Yong, MENG Ling-fei. Dielectric Breakdown Properties of Biodegradable Polyethylene Film Immersed in Contamination Solution[J]. Journal of Materials Engineering, 2009, 0(7): 54-57,92.
Eco-friendly insulating materials have been expected to solve severe environmental pollution caused by electric and electronic insulating castoffs.As typical friendly-environmental materials,biodegradable polymers are needed systematical investigation on their electrical properties for the substitute of present insulating materials.Biodegradable polyethylene(BDPE) films were employed as the specimens and high density polyethylene(HDPE) films were selected as the reference.Effects of contamination level on dielectric breakdown properties of BDPE film immersed in artificial saline solutions were investigated by using DC voltage.The breakdown craters were captured by using a monocular-video-zoom microscope.An image-pattern-identification technique was applied to calculate the breakdown area and box dimension of breakdown craters.Obtained results revealed that for both BDPE film and HDPE film,breakdown voltage,breakdown area and box dimension all decrease with increasing the contamination level.By comparing the test results,it showed that under contaminated conditions,breakdown endurance of BDPE film is better than that of HDPE film.
DU Feng-shan, WANG Dan-chao, YAN Liang, DAI Sheng-long, YANG Shou-jie. Fatigue Life Analysis of Aluminum Alloy 2E12 Plates with Center Holes[J]. Journal of Materials Engineering, 2009, 0(7): 58-61,66.
On the basic of the fatigue tension test of aluminum alloy 2E12,the process and realization process of fatigue life prediction is deeply introduced by using FEM software ABAQUS and fatigue analysis software MSC.Fatigue.Numerical simulation results are consistent with the theoretical calculation results and the reliability of numerical simulation to analyze the fatigue life of products is verified.Then aluminum alloy 2E12 plates models with different aperture to analyze fatigue life are created.The results show that the ratio of aperture and the length has a marked impact on fatigue life and D/L has power function relation with logarithmic life.
ZHANG Shou-quan, ZHU Jing-lei, HUANG Ji-hua, WANG Hai-tao, ZHANG Hua, ZHAO Xing-ke. Tribological Performance of TiC/Fe Coatings Fabricated by Reactive Plasma Spray[J]. Journal of Materials Engineering, 2009, 0(7): 62-66.
TiC reinforced Fe-based cermet coatings have been deposited on the mild steel substrate by reactive plasma spraying using Fe-Ti-C powder prepared by a precursor pyrolysis process.Microstructure,phase composition and wear surface of the coatings were examined by means of scanning electron microscopy and X-ray diffraction.Friction and wear test of TiC/Fe coatings and substrate were investigated by SRV abrasive tester.The results show that the TiC /Fe cermet coatings with 53%(mass fraction)TiC ceramic phases exhibited better abrasive wear resistance and about 25 times higher than that of the 45 mild steel.The adhesive wear and micro-spalling are the major wear mechanism of the TiC/Fe coatings fabricated by reactive plasma spraying.
MU Ren-de, XU Zhen-hua, HE Shi-mei, HE Li-min, CAO Xue-qiang. La2(Zr0.7Ce0.3)2O7——a New Oxide Ceramic Material for Thermal Barrier Coatings[J]. Journal of Materials Engineering, 2009, 0(7): 67-71,78.
La2(Zr0.7Ce0.3)2O7(LZ7C3) as a candidate material for thermal barrier coatings(TBCs) was coated by electron beam-physical vapor deposition(EB-PVD).The composition,crystal structure,surface and cross-sectional morphologies and isothermal oxidation behavior of the LZ7C3 coating were studied.The results indicate that the composition of LZ7C3 coating deviates from the ingot through energy dispersive spectroscopy(EDS) detection,however,the X-ray diffraction(XRD) pattern of the coating is similar with the ingot.By CeO2 adulteration,the linear thermal expansion coefficient(TEC) of LZ7C3 bulk is larger than that of La2Zr2O7(LZ),and the isothermal oxidation performance of the LZ7C3 coating is superior to that of traditionally zirconia containing 8%(mass fraction) yttria(8YSZ) after isothermally oxidized at 1100℃ for 890h.The failure of the LZ7C3 coating is mainly a result of the TEC mismatch,the abnormal oxidation of bond coat and the occurrence of micro-cracks inside ceramic topcoat.
WANG Dong-sheng, TIAN Zong-jun, CHEN Zhi-yong, SHEN Li-da, LIU Zhi-dong, HUANG Yin-hui. Study on Laser Remelting MCrAlY Coatings Prepared by Plasma Spraying on TiAl Alloy Surface[J]. Journal of Materials Engineering, 2009, 0(7): 72-78.
To improve the hightemperature oxidation resistance of the MCrAlY coatings prepared by plasma spraying on TiAl alloy surface,laser remelting experiment had been carried out and the effects of laser remelting on microstructure and oxidation resistance on the coatings were researched.The surface morphology,microstructure and phase of the coatings before and after oxidation were investigated using scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS) and X-ray diffractometry(XRD).The results show that the coating has a higher compactness and the lamellar structure of plasma-sparyed coating is eliminated after laser remelting.Meanwhile,aluminum is redistributed at the top of the remelted coating and forms an Al-rich region because of relative low density of Al.The plasma-spayed MCrAlY coating has better oxidation resistance than the original TiAl alloy,and the laser-remelted coating has the best oxidation resistance.
ZHU You-li, LI Zhan-ming, HE Jia-wu, WANG Yong. Microstructure Changes of 2A12 Aluminum Alloy Weld Bead Surface Layer by Ultrasonic Impact Treatment[J]. Journal of Materials Engineering, 2009, 0(7): 79-82.
2A12 aluminum alloy welded joint was strengthened by Ultrasonic Impact Treatment(UIT).The microstructure characterization of the welded bead surface layer with and without UIT was studied by SEM observation and X-Ray Diffraction(XRD) analysis.Results show that the metallurgical structure of the near surface material of the weld zone was densified due to ultrasonic impact treatment.The depth of plastic deformation extended up to about 300μm from the surface.The grain refinement behavior was obvious.XRD analysis show that the diffraction peaks after UIT was broadened significantly,which was related to grain refinement and lattice distortions.Quantitative estimation of the grain size and of the lattice distortions after UIT was evaluated by Scherrer equation and Williamson formula based on the peak broadening.Results show that the average grain size after UIT is about 123nm and the average micro-strain value is about 0.134%.At last,the mechanisms of grain refinement were discussed.
LIU Pei-sheng, XIA Feng-jin, LUO Jun. Analyses of the Classical Model for Porous Materials[J]. Journal of Materials Engineering, 2009, 0(7): 83-87.
New developments are ceaselessly gained for the preparation,the application and the property study of porous materials.As to the theories about the structure and properties of porous materials,the famous classical model—Gibson-Ashby model has been being commonly endorsed in the field of porous materials all over the world,and is the theoretical foundation widespreadly applied by numerous investigators to their relative researches up to now.Some supplementary thinking and analyses are made for the shortages in this model in the present paper,and it is found that some shortages can even break the completivity originally shown by this model.Based on the summery about these problems,another new model is introduced which can make up the shortcomings existed in Gibson-Ashby model.
LIU Shi-min, ZHOU Yu. Study on Development and Tendency of Bioactive Coatings on Titanium Alloys Surface[J]. Journal of Materials Engineering, 2009, 0(7): 88-92.
Hydroxyapatite is usually prepared on the titanium and titanium alloys surface in order to get bioactive coatings.The research goes through four stages,such as single ordinary hydroxyapatite coating,composite coating,nano-coating,and gradient coating.The questions of different coatings are analyzed.The nanostructure gradient coatings will be a new direction for the coating on the titanium and its alloys surface.
