XUE Ke-min, ZHANG Qing, LI Ping, DUAN Yuan-pei. Hot Deformation Behavior of β21S Alloy at Elevated Temperature[J]. Journal of Materials Engineering, 2008, 0(4): 1-4,69.
Hot compression tests of β21S alloy were performed on Gleeble-1500 tester at strain rates ranged in 0.01-1s-1 and deformation temperature 750-1100℃.The effect of deformation conditions on flow stress and microstructure of the tested alloy was studied.The deformation activation energy and corresponding stress exponent under hot-compression evaluated quantitatively,the model of flow stress was obtained.The results show that the flow stress is obviously affected by strain rate and deformation temperature.The flow stress becomes higher with increase of strain rate at constant temperature,and lower with increase of deformation temperature at constant strain rate.The recovery only occurs at higher strain rate and on lower temperature,par recrystallize occurs and the degree of recrystallize increases with decrease of strain rate and increase of temperature.The deformation activation energy 211.04kJ/mol and corresponding stress exponent 4.0129 were obtained respectively.
JIANG Min-hong, GU Zheng-fei, CHENG Gang, CHENG Jun, ZHAO Jia-cheng. Preparation and Properties of Rare Earth-iron Giant Magnetostrictive Material with 533 Axial Alignment[J]. Journal of Materials Engineering, 2008, 0(4): 5-7,73.
Tb0.3Dy0.7Fe2 alloys with (533) axial alignment were prepared by an electric arc melting-directional solidification technique and controlling melting temperature and heat flux orientation.The results shows that Tb0.3Dy0.7Fe2 alloys have a higher magnetostriction,and the magnetostriction λ∥ and λS arrive 1045×10-6,856×10-6 respectively under 0MPa stress and 400 kA·m-1 magnetic field.X-rays diffraction shows that there is(533) strongest peak for the axial orientation of alloy rod with(311),(110) weak peaks,and there are(110),(220),(311),(511) peaks which are all weaker for the transverse-cross orientation.Moreover,the hysteresis loop of the alloy was also tested and discussed.
LIAO Shu-lun, ZHANG Li-wen, YUE Chong-xiang, GUO Shu-qi, ZHEN Yu. Research on Thermal Deformation Behavior and Model of Flow Stress of GCr15 Steel[J]. Journal of Materials Engineering, 2008, 0(4): 8-10,14.
The behavior of thermal deformation of GCr15 steel had been investigated by single-stage compression tests on Gleeble-3800 thermal-mechanical simulator.The deformation temperature ranged from 950℃ to 1150℃,and the strain rate ranged from 1s-1 to 10s-1.A hyperbolic sine equation was employed to describe the relationship between the peak stress and Zener-Hollomon parameter,in which the activation energy of deformation and other constants were obtained using regression analysis.Meanwhile,the equation for peak strain and the model of flow stress were also obtained.It is shown that the predicted results of the flow stress equation are good agreement with the experimental data.
HAN Xiao, WANG Yuan-sheng. Effect of Emulsion Polymerization Conditions on Permeabilities of Fe3O4/Conductive Polyaniline Nanoparticles[J]. Journal of Materials Engineering, 2008, 0(4): 11-14.
Electrically conducting polyaniline(PANI)-magnetic oxide(Fe3O4) composites with electrical and ferromagnetic behaviors were synthesized by the way of emulsion polymerization in the presence of dodecyl benzene sulfonic acid(DBSA) as a surfactant and dopant and ammonium persulfate(APS) as the oxidant.The permeabilities of Fe3O4/DBSA-PANI nanocomposites with core-shell structure were studied by varying the contents of Fe3O4,DBSA and APS.The results show that the Fe3O4 can improve the magnetic loss of the composites remarkably and widen the absorbing wave band.The contents of DBSA and APS have the less influence on the permeabilities of the composites because they mostly influence the conjugated structures and conductivities of the PANI,but the excessive DBSA and APS will increase the number of interfacial atoms and dipoles in the composites and therefore make the permeability have a fluctuant change.The different dissipative mechanisms were discussed to explain the varieties.
CAO Mao-sheng, ZHOU Wei, LEI Yi-long, RONG Ji-li. Behavior Characterization of Dynamic Mechanical Response for Carbon/Epoxy Composites Under Compressive Load[J]. Journal of Materials Engineering, 2008, 0(4): 15-18.
The compressive tests were performed to obtain the dynamic mechanical properties of a novel carbon fiber reinforcement epoxy composites at high strain rate range.The dynamic compressive properties were investigated utilizing the Split Hopkinson Pressure Bar(SHPB) apparatus through the normal direction as well as the in-plane direction under high velocity impact loading.Based on the test results,the dynamic stress-strain relation was obtained at four different strain rates loading,respectively.At the same time,the fractography of the samples was characterized by the SEM method.The results showed that the dynamic compressive strength and the failure strain of the laminated samples in the normal direction were higher than that in the in-plane direction at high strain rates.The main damage and fracture modes were matrix crack,delamination and shear fracture under the dynamic compressive loading.
LI Shu-lan, XU Ren-ping. Comparison Analysis for 40CrMnSiMoVA Bar and Forging Crack Growth Character[J]. Journal of Materials Engineering, 2008, 0(4): 19-22,46.
Based on study of mechanical performance of 40CrMnSiMoVA bar and forging,their crack growth character is statistically analyzed,mean value and variance are statistically tested.The result showed that crack growth rate and life of both material increase with crack increase,the divergence of crack growth life increases with crack length increases,the divergence of crack growth rate decreases at the beginning and increases in the end with crack length increase.The divergence of 40CrMnSiMoVA forging is larger than that of bar material.The results can be used for material selection and application.
DING Xin-bo, ZHANG Hui-ping, YAN Xiong. Effect of the State of Organic Small Molecule in Hybrid Materials on Damping Properties[J]. Journal of Materials Engineering, 2008, 0(4): 23-26,42.
The damping properties of organic hybrids consisting of chlorinated polyethylene(CPE),2,2′-methylene-bis-(6-tert-butyl-4-ethyl-phenol)(EBP),and 2′-methylene-bis-(4-methyl-6-cyclohexyl-phenol)(ZKF) have been investigated by dynamic mechanical analysis(DMA) and differential scanning calorimetry(DSC).The dynamic mechanical thermal properties of CPE/EBP hybrid materials show that all CPE/EBP hybrid samples clearly exhibit two significant peaks except the CPE/EBP with 5% mass fraction,and a novel relaxation peak appears above the glass-transition temperature of CPE,implying that there is a CPE-rich matrix phase and an EBP-rich domain co-existed in CPE/EBP hybrids.However,there is only one loss peak for all the samples of the CPE/ZKF hybrids and the height of the loss peak increases drastically with the increased content of ZKF.From the DSC measurements,we find that all of the CPE/ZKF hybrid samples are almost in an amorphous state and has only one phase.These may imply that the dispersal state of the organic filler in polymer matrix plays a great role in the damping properties of the organic hybrid materials.
REN Peng-gang, LIANG Guo-zheng, ZHANG Zeng-ping. Study on Curing Reaction of Bisphenol A Dicyanate Ester and Its Epoxy Modified Systems[J]. Journal of Materials Engineering, 2008, 0(4): 27-32,37.
The reaction mechanism and product structure of bisphenol A dicyanate ester(BADCy) resin and its epoxy(E51 and E20) modified systems were investigated by DSC and FTIR.The results showed that the polycyclotrimerize reaction took place in BADCy.While the main reaction in epoxies modified system at low temperature(<180℃) were: Cyclotrimerization of cyanates,polyetherfication of epoxy groups and cyclotrimerization of cyclic dimmers and the formation of oxazoline ring.At high temperature(>200℃),the formation of oxazolidinone ring were dominant.The contents of cyclotrimerization,polyetherfication,oxazoline ring and oxazolidinone ring were mainly dependent on the content of epoxy group in the modified systems and the curing temperature.
KE Li-ming, PAN Ji-luan, XING Li, QIN Zhan-ling. Physical Mechanism of Friction Stir Weld Formation of Aluminum Alloy[J]. Journal of Materials Engineering, 2008, 0(4): 33-37.
The physical mechanism of the weld formation during friction stir welding and the influence of welding parameters on the size of weld nugget were investigated.The results shown that,the friction stir weld is composed of three parts of metals,that is,the weld nugget,the metal flowing along the thickness of the workpiece at the trail of the advancing side,and the from the two sides of the stir pin.There exist a confluence region to which the metal flows from four directions on the weld cross section.If the metal flowing is not enough,the weld defects would form in this region.The formation of the nugget and its size are dependent on the screw threads on the stir pin surface and the welding parameters.The more the metal flowing to the bottom of the workpiece under the driving of the screw threads in unit weld length,the larger the weld nugget near the bottom is.If the rotation speed of stir tool is too high or the travel velocity of the tool is too low,the metal around the stir pin would be easy to flow to the upper part of the weld,and this will decrease the size of the nugget.
DAI Qing-wei, ZHANG Ding-fei, YUAN Wei, SHI Guo-liang, DUAN Hong-ling. Researches on Extrusion,Microstructure and Mechanical Properties of New Mg-Zn-Mn Alloy[J]. Journal of Materials Engineering, 2008, 0(4): 38-42.
It was found that the new Mg-Zn-Mn wrought magnesium alloy could be extruded at 310℃ while complete dynamic recrystallization took place during extruding.Solution and aging treatment,especially 2-step aging,can significantly increase the strength of the alloy which can achieve the strength of the high strength ZK60 wrought magnesium alloy.
ZHAO Peng, PU Yu-ping, HUANG Chun-hui, LU Guang-shu. Effect of Adding Ultrasonic on Copper Electroless Plating of Polyurethane Foam[J]. Journal of Materials Engineering, 2008, 0(4): 43-46.
To research the influence of adding ultrasonic on the process that electroless plating copper film on the framework of polyurethane foam,the paper respectively investigated the effect of adding ultrasonic on the Sn-Pd activated polyurethane foam directly and on the copper film covered framework.The result shows that adding ultrasonic on the copper film covered framework can shorten the inducing time and elevate the speed of the reaction,and the lifting rate of weight increasing slows down while the ultrasonic power augments.When adding ultrasonic on the Sn-Pd activated polyurethane foam,which had not been covered with continuous copper film,the palladium nuclei could be shocked away from the framework,so the ultrasonic should be added after 5 minutes' pre-plating at least.
WANG Yun, SUN Ri-wen, XU Zhen-ying, DAI Ya-chun, ZHANG Kai, YUAN Guo-ding, CAI Lan. Investigation into the System and Numerical Simulation of Warm Microextrusion[J]. Journal of Materials Engineering, 2008, 0(4): 47-50.
One of the main occurring problems in miniaturization of part size is size effects,which demanding new requirements especially on microforming theory,apparatus and process etc.Warm microextrusion process is proposed in view of micro extrusion in cold and hot forming insufficiency.Then,the self-designed warm microextrusion system is presented in the review of the state of art in microforming apparatus,and its principle is carried on the elaboration.In order to explore the flowing behavior of workpiece in the microextruding cylinder,ABAQUS/Explicit module is utilized to carry on the numerical simulation for warm microextrusion,the stress distribution and metal flowing behavior under different friction conditions in the warm extruding process at 210℃ are analyzed.From the results,we can obtain the influence of the different process parameters on warm microextrusion and the corresponding microforming laws,which offers the scientific theoretical foundation on its mould optimization design.
PENG Yuan-dong, YI Jian-hong, GUO Ying-li, LI Li-ya, LUO Shu-dong. Effects of Soaking Time on Microstructure and Properties of Microwave Sintering Fe-2Cu-0.6C Alloy[J]. Journal of Materials Engineering, 2008, 0(4): 51-55.
The properties and microstructure of microwave sintering Fe-2Cu-0.6C alloy at 1150℃ for different soaking time were studied,and compared with that of the conventional sintered samples under the same sintering temperature properties.The results showed the microwave sintered properties were higher than conventional sintered.The properties reached optimal,when the microwave sintering soaking time changed from 5min to 15min.The density was 7.22 g/cm3,HRB was 78,tensile strength was 416.8 MPa and elongation was 5.5%.But prolonged soaking time to 20min,the properties were not changed.Optical microscopy revealed that microwave sintered sample had finer microstructures,as small,rounded,and uniformly distributed pores,which was advantageous to obtain the tiny crystal grain and high density.There were much flaky and granular pearlite compared with the conventional sintered,so microwave sintering can significantly improve the sample's performance.Through fracture analysis,the conventional sintered was brittle intergranular fracture and microwave sintered was mixed fracture made up of brittle intergranular and ductility intergranular fracture.
WANG Li-juan, LI Jian, LIU Yi-xing. Study on Preparation of Electromagnetic Shielding Composite by Electroless Copper Plating on Fraxinus Mandshurica Veneer[J]. Journal of Materials Engineering, 2008, 0(4): 56-60.
Electromagnetic shielding composite was prepared by electroless copper plating using hypophosphite as reducing agent.Effect of temperature and pH value of plating solution on composition and electrical performance of coatings were investigated.Surface morphology of electroless plated veneers and the composition of the copper coating were observed and determined by scanning electronic microscope(SEM) and energy dispersive X-ray analysis(EDAX).Crystal structure of the coating was investigated by X-ray diffraction(XRD).Low-resistance measuring instrument and spectrum analyzer were used for measuring surface resistance and electromagnetic shielding effectiveness(ESE).The results show that porous structure of wood itself still exists on plated veneer,and the surface of wood veneer is covered by the coating entirely.It is found that temperature and pH value have effects on composition,surface morphology of the coating and electrical performance of the composite in the course of plating.Excessively low or high temperature and pH value are adverse for copper deposition.The surface resistivity and ESE of plated veneer under temperature 70℃ and pH value 9.8 are lower and higher,respectively.Copper is elementary substance mixed a small quantity of nickel,phosphour and cuprous oxide in the coating which is more compact.The resistivity transverse and parallel fiber direction are 0.139Ω/cm2 and 0.111Ω/cm2,and the ESE is about 55-60dB in the frequencies from 10kHz to 1.5GHz.
WANG Yuan-kun, CHENG Chang-zheng, HU Zong-jun, NIU Zhong-rong. Analysis of Functionally Graded Coatings by Boundary Element Method[J]. Journal of Materials Engineering, 2008, 0(4): 61-64.
The analytic formulations of the nearly singular integrals were introduced into the boundary element method(BEM) of the coating structures.The strength of the coating structures under Hertzian type pressure was modeled by BEM.The isotropic and functionally graded coatings were considered,respectively.The Tresca stress contours in the coating structures were portrayed.The numerical results showed that there were stress discontinuities at the coating-substrate interface when the isotropic coating was used.The discontinuity could be attenuated when the isotropic coating was replaced by the functionally coating.In addition,the maximum value of Tresca stress in the coating could be reduced.
LIU Ying-ying, YAO Ze-kun, GUO Hong-zhen. Progress in Studying on Superplasticity of Ti3Al Intermetallic Compound[J]. Journal of Materials Engineering, 2008, 0(4): 65-69.
The progress in studying on the superplasticity of Ti3Al intermetallic compound is summarized and evaluated in detail.According to the results that have been obtained,the optimal superplastic deformation temperature as well as strain rate of this kind of alloy are within 940-980℃ and 10-4-10-3 s-1,respectively.Its largest elongation is about 1500%,which approaches the superplasticity level of the conventional Ti alloy.Its main mechanism of superplasticity deformation is grain boundary sliding,and the main reason of failure is the formation and conjunction of the voids.In the light of the experimental results and the existing questions,further research and some prospects are proposed.
XIAO Xuan, LU Shi-qiang, HU Ping, HUANG Ming-gang, NIE Xiao-wu. Progress in Research on Alloying Effect in Laves Phase NbCr2 Intermetallic Compound[J]. Journal of Materials Engineering, 2008, 0(4): 70-73.
Alloying toughening mechanism on Laves phase NbCr2 intermetallic compound is reviewed.The general effects of alloying elements on the phase stability,microstructure and mechanical property are discussed.The existing problems and development prospects are suggested.
LI Xiao-bing, LIU Ying. Control and Prepartion to Wettability of Material Surfaces[J]. Journal of Materials Engineering, 2008, 0(4): 74-80.
Wettability is one characteristic of material surface.The main factors to wettability are surface energy,surface roughness and micro/nano structure.Low surface energy is the basic condition of super-hydrophobic surface.Then,surface roughness and micro/nano structure are crucial factors.By theory studies and experiment testification,the contact angles increase with reducing surface energy or adding surface roughness,and are affected by micro/nano structure of material surfaces.Organic silica,fluorin resin,and its modified resin are low surface energy materials in common use.The methods to roughening surface and formatting micro/nano structure are templet method,CVD,sol-gel,micro machining,particle filling,etc.Furthermore,there are progresses on reversion from hydrophobic to hydrophile.
