ZHAO Xi-hong, SUN Yue-jun, HUANG Zhao-hui, GONG Sheng-kai. Creep Deformation Mechanism of Directionally Solidified Ni3Al-base Superalloy IC10 at 760℃[J]. Journal of Materials Engineering, 2009, 0(1): 1-3,9.
The creep behavior of directionally solidified superalloy IC10 was investigated at 760℃/750MPa and the deformation mechanism was studied.The results showed that anti-phase boundary(APB) and stacking fault(SF) were observed by using TEM,which indicated that the dislocations cutting through γ’ precipitates was the main creep deformation mechanism at 760℃.The morphology of cracks were observed by SEM,the cracks initiated from the interface between γ matrix and carbides,and extended along the direction normal to the applied stress.
HE Yong-sheng, GUO Xi-ping, SUN Zhi-ping, JU Xiao-chuang. Microstructure and Compositional Distribution in Arc-melted Advanced Nb-silicide-based Ultrahigh Temperature Alloy[J]. Journal of Materials Engineering, 2009, 0(1): 4-9.
The ingot of Nb-Ti-Si-Cr-Al-Hf-Mo-B-Y ultrahigh temperature alloy was prepared by firstly vacuum non-consumable arc melting and then vacuum consumable arc melting.The microstructures,constituent phases and compositional distribution in the master alloy ingot were analyzed.The results showed that the main constituent phases of the ingot were Nb solid solution(Nbss),(Nb,X)3Si and(Nb,X)5Si3(where X represents Ti,Hf and Cr elements).The microstructure of the ingot mostly consisted of primary Nbss dendrites,Nbss+(Nb,X)5Si3 eutectic colonies(lamellar or petal-like) and(Nb,X)3Si blocks.However,the microstructure in the central parts of both the top and bottom of the ingot was composed of Nbss+(Nb,X)5Si3 eutectic colonies,with little primary Nbss dendrites or(Nb,X)3Si blocks.The compositional distribution was not uniform in the master alloy ingot.The Si content increased from the edge part to the central part,and the Ti content decreased from the edge part to the central part of the ingot.
LIU Xue-feng, MA Sheng-jun, LIU Jin-ping, XIE Jian-xin. BP Neural Networks Models for Constitutive Relationship During High Temperature Deformation Process of Cu-12%Al Alloy[J]. Journal of Materials Engineering, 2009, 0(1): 10-14.
On the basis of the compression experiment data obtained from Gleeble-1500 thermal simulator,the predicted model of the whole process of high temperature deformation for the relation between true stress and true strain,strain rate and temperature for Cu-12%(mass fraction)Al alloy was developed with BP Neural Network(BPNN) method.The results show that BPNN method is feasible to establish whole process of high temperature compression deformation constitutive relation model of Cu-12%Al alloy.The average relative error between predicted and experimental data of true stress is less than 1.8%,and the predicted model can reflect the real feature of the practical deformation process.
ZHANG Xiu-li, SUN Xiao-hui, LI Ming-yang. Evolution of Persistent Slip Bands in Fatigued Copper Single Crystals Under Intermediate Temperature Recovery[J]. Journal of Materials Engineering, 2009, 0(1): 15-18.
In single-slip-oriented copper single crystals which were cyclically deformed under constant plastic shear strain amplitude control,Persistent Slip Bands(PSBs) was formed.Under intermediate temperature recovery of copper(0.3-0.5)TmK,by means of different temperature and different period of time,fatigued copper single crystals with PSBs were annealed in vacuum.The results show that during intermediate temperature recovery,the interaction of elastic force,penetrating force and tree dislocation resistance drive dislocations motion through annihilation and diffusion of vacancies and vacancy clusters,make some dislocations walls of PSBs bending and thinning,finally disappearing part by part under the mechanism of annihilation and have the density of dislocation falling rapidly.With the energy importing by an annealing treatment,the service life of "damage" components can be extended.
MA Qin-qin, ZHENG Wei-wei, LI Xing-wu. Microstructures of TC16 Titanium Alloy Annealed at Different Conditions[J]. Journal of Materials Engineering, 2009, 0(1): 19-22.
The effects of annealed process on the microstructure of TC16 were investigated.The results show that only α and β phases are observed at all annealing conditions.The microstructure is characterized by lamellar α and equiaxed α grains distributing on β matrix when TC16 is annealed at α + β region.With the increase of annealed temperature the degree of α spheroidization and α grain size are all increased.With the increase of holding time the amount of equiaxed α grains and the grain size are increased.Under air cooling condition,the size of both lamellar α and equiaxed α are smaller.When annealed at β single phase region,α phases are formed along the original β grain boundaries and in the coarse β grains.In one β grain several zones of different-oriented lamellar α exist.
YANG Li-ying, DONG Xiao-ping, LI Xiao-ting, LIU Wei, LU Min-xu. Microstructure of Welded Joint for X60 Steel Welded with ECrNiMo-3[J]. Journal of Materials Engineering, 2009, 0(1): 23-27.
SEM and TEM were used to observe and analyze the microstructure of welded joint formed by ECrNiMo-3 welding electrode fabricating X60 steel.EDS was utilized to examine the distribution of alloying elements including of Fe,Ni,Cr and Mo element at each zones of weld joint,the content of Mn and C in the partially melted zone was obtained by calculation.The result shows that the dendritic structure is formed at entire mix zone and Mo segregates into inter-dendrite.Unmixed zone is planar crystals by united growth from partially melted zone of X60 steel.There is no segregation phenomenon and the width of the zone is about 30μm.The content of Fe gradually decreases and the variation trend that of Cr,Ni,Mo is reverse from fusion line to entire mixed zone,so the unmixed zone is alloy element transition zone.The partially melted zone composes of martensite and the second phase particles with 200nm width.
YU Mei, LI Song-mei, LIU Jian-hua, CHEN Dong-mei. Preparation of Nickel Coatings on T-ZnO Whiskers and Their Electromagnetic Performance[J]. Journal of Materials Engineering, 2009, 0(1): 28-31,36.
Nickel coatings were prepared on the surface of T-ZnO whiskers by electroless plating technique.The morphology,components and crystal structure of the T-ZnO whiskers powders after coated were characterized by SEM,EDS and XRD.The result showed that the nickel films were successfully coated on the surface of T-ZnO whiskers.The nickel films had an amorphous structure with a little mass fraction of phosphorus at about 2%.The electromagnetic parameters of the composite powders of Ni/T-ZnO demonstrated that the composite powders of Ni/T-ZnO whiskers possessed more effective microwave absorption properties compared with T-ZnO whiskers.The value and frequency of minimum reflection loss of the composite powder changed with the time increment of the electroless plating.The minimum reflection loss can reach-17.5dB at the frequency of 11.7GHz.
XU Li-ning, ZHANG Ying-huai, LU Min-xu, XU Xi-cheng, QIN Jie. Mechanism of Oxidation Pre-treatment Improving Effect of Silane Treatment on Steel[J]. Journal of Materials Engineering, 2009, 0(1): 32-36.
The interface bonding of steel/oxidation film/silane film/epoxy coating system was studied using SEM,EDX and FTIR.By comparing the steel/silane film/epoxy coating system,the influence of oxidation film on the polymerization and interface structure of silane film was studied.The results show that for the oxidation sample the tension shear fracture is mainly on the silane/coating interface.While,for the sample without oxidation,the fracture is mainly on the steel/silane interface.The oxidation film can restrain the self-polymerization of silane and improve the coating/steel bonding strength.
GUO Yun-shu, PAN Qing-lin, NIE Bo, HE Zhen-bo, YIN Zhi-min. Investigation on Aging of 2A23 Alloy for Age-forming[J]. Journal of Materials Engineering, 2009, 0(1): 37-40.
Tensile test,Vickers hardness test and TEM analysis were used to study the aging treatments and the microstructures and mechanical properties under different aging treatments of 2A23 aluminum alloy for age-forming.The results show that the suitable aging temperature is 170℃ and aging time is 20h.S’phase is the main strengthening phase of the alloy.The pre-deformation before aging can make S’(Al2CuMg) precipitation distribute more dispersively and homogenously,thus can greatly improve tensile strength.The strength of the alloy improves with the increasing of pre-deformation,but over pre-deformation resulted in the decreasing of the plasticity of the alloy.The favorable pre-deformation is about 2.5%-5%.
ZHU You-li, YE Xiong-lin, HE Jia-wu, LI Li, HUANG Yuan-lin. Mechanism on Improvement of Fatigue Performance of Pre-corroded 7A52-CZ Aluminum Alloy by Ultrasonic Deep Rolling Treatment[J]. Journal of Materials Engineering, 2009, 0(1): 41-45.
The effects of an ultrasonic deep rolling(UDR) treatment on the fatigue behavior of pre-corroded 7A52-CZ aluminum alloys were investigated.7A52 aluminum alloy specimens were corroded in exfoliation corrosion(EXCO) solution at different durations.Some corroded specimens were treated by UDR.Fatigue tests were carried out for the uncorroded,corroded and UDR treated specimens.By means of X-ray diffraction stress measurements and scanning electron microscopy(SEM),residual stress and fractograph of 7A52 aluminum alloys with and without UDR treatment were analyzed.The results indicated that UDR produced compressive residual stresses with depth approaching 1mm.UDR treatment can extend the fatigue life of the pre-corroded 7A52 specimens to a large extent,depending on the level of corrosion and UDR parameter.For the light corroded specimens,UDR treatment changed the fatigue crack nucleation site from surface to the transition zone between the compressive residual stresses and tensile stresses,resulted in a much longer fatigue life.For the severely corroded specimens,the crack still nucleated by intergranular cracking,however,due to the compressive residual stresses introduced and the closure of the corrosion pits and corrosion microcracks,UDR treatment still improved fatigue performance of the pre-corroded 7A52 aluminum alloy substantially.
YANG Zhi-li, CHEN Deng-ming, LIAO Dao-han. Numerical Simulation on Directional Solidification Process of Al-Ni-Co Alloy[J]. Journal of Materials Engineering, 2009, 0(1): 46-49.
By the aid of finite element analysis method,transient temperature fields of Al-Ni-Co magnetic steel directional solidification process were simulated.The influence of different technological conditions on the temperature gradient and growth velocity of liquid-solid interface was analyzed.The results show that,with molten steel temperature increasing,the ratio of temperature gradient to growth velocity of liquid-solid interface rises sharply during the initial solidification period and then changes from 2000℃·s·cm-2 to 6000℃·s·cm-2.When the liquid-solid interface reaches 5-6cm,the ratio decreases rapidly and tends to coincide.The numerical simulation can provide an available tool to optimize the directional solidification process of Al-Ni-Co alloy.
DANG Xu-dan, TAN Yong-gang, XIAO Jun, LI Yong, YUAN Yong-hu. Finite Element Modeling Analysis of Compressive Modulus About X-cor Sandwich[J]. Journal of Materials Engineering, 2009, 0(1): 50-54.
Through the contrast of two finite models a finite element computational model of compressive modulus about X-cor sandwich was proposed.The finite element software ANSYS was used in the computation of compressive modulus.Through numerical analysis the stress field and compressive modulus of X-cor sandwich were achieved,the effect of changing radius,density,angle and volume fraction of Z-pin to the compressive modulus of X-cor sandwich was analyzed.The numerical analysis results indicate that as the radius,density and volume fraction of Z-pin increase the compressive modulus of X-cor sandwich increases,as the angle of Z-pin increases the compressive modulus of X-cor sandwich decreases and the compressive modulus of X-cor sandwich has a linear relation to the volume fraction of Z-pin.In addition changing radius of Z-pin and changing density of Z-pin have a same effect to the compressive modulus of X-cor sandwich.Via the computation of finite model the influencing trends of the X-cor sandwich parameters to its compressive modulus are achieved and the rationality of the proposed finite model is verified.
CAO Wei-wei, ZHU Bo, WANG Cheng-guo. Investigation on Correlation Between Microstructure and Thermal Radiation Property for Carbon Fiber[J]. Journal of Materials Engineering, 2009, 0(1): 55-58,63.
The normal spectral emissivity and normal total emissivity of T700 carbon fiber,T300 carbon fiber and its surface desizing sample by current were measured by automatic instrument for spectral radiation measurement,and the correlation between microstructure and thermal radiation property for carbon fiber was investigated.The results show that the normal total emissivity of T700 carbon fiber and T300 surface desizing carbon fiber are lower than T300 original sample,and the variation of spectral emissivity is in three wavebands,this is related with the microstructure of carbon fiber.The spectral emissivity in 2500nm to 5000nm waveband is influenced on free carrier transition mechanism,and the spectral emissivity in 5000nm to 6500nm waveband and 6500nm to 13000nm waveband are related with the libration of C—C bond in carbon planes and the proportion of amorphous carbon in microstructure respectively.
SUN Jian-bo, LIU Wei, LU Min-xu. Electrochemical Corrosion Behavior of 16MnR Steel with Plastic Strain in CO2 Environment[J]. Journal of Materials Engineering, 2009, 0(1): 59-63.
Oil country tubular goods often service under stress and strain conditions.In order to investigate the effect of stress and strain on CO2 corrosion behavior of 16MnR steel,electrochemical measurement techniques were employed to determine the electrochemical impedance spectra(EIS),linear polarization resistance(LPR) and corrosion potential(Ecorr) after different plastic deformation.The results show that the corrosion potential shifts in negative direction,linear polarization resistance decreases,and corrosion rate increases with increasing strain.The Nyquist plots of EIS spectra under tensile and compressive strain exhibit two semicircles: a first capacitance loop at high frequency and a second inductance loop at low frequency.The distance along the real axis where the two loops appears decreases with increasing strain,which indicates the total impedance resistance decreases with strain.Cold working deformation improves the electrochemical activity of 16MnR steel,which increases the anodic dissolution and corrosion rate.
LIANG Li-yun, TAN Bi-en, ZENG Yi-bing, ZHANG Lian-zheng, PAN Hui-ming. Effect of Atomic Oxygen on Property of Addition Silicone Rubber[J]. Journal of Materials Engineering, 2009, 0(1): 64-69.
The atomic oxygen(AO) resistance of the thermal control coatings was tested by the ground-based simulation facility of coaxial source atomic oxygen and the mechanism of AO resistance was studied by using attenuated total-internal reflection fourier transform infrared spectroscopy(ATR FT-IR),X-ray photoelectron spectroscopy(XPS) and scanning electron microscopy(SEM).The results show that the thermal control coatings which was made by low molecular vinyl rubber have the good resistance of AO exposure,and the filler ZnO coated by potassium silicate will make the resistance of AO exposure of the additional silicone rubber decrease.
CHENG Xing-wang, LI Xiang, YU Zhou, LONG Xue. Magnetic Properties Study on Mn Doped ZnO Synthesized by Chemical Method[J]. Journal of Materials Engineering, 2009, 0(1): 70-73.
Mn doped ZnO Dilution Magnetic Semiconductors(DMSs) samples with nominal composition Zn0.993Mn0.007O were fabricated by chemical method.The structural and magnetic properties as well as optical properties of the synthesized samples were studied.The results indicated that samples sintered at temperatures below 600℃ showed a single wurtzite ZnO structure with prominent ferromagnetism at room temperature,while sample sintered at 800℃ a second phase,namely,ZnMnO3 observed with significant reduced ferromagnetism and an enhancement of paramagnetism.Structural and optical properties study demonstrated that the ferromagnetism observed in the studied samples was originated from the doping of Mn in the lattice of ZnO crystalline,which confirmed intrinsic room temperature ferromagnetism in(ZnMn)O crystal.
LUO Chu-yang, XIONG Jun-jiang, CHENG Ze-lin, LI Hong-yun, PENG Bo. Experimental Investigation on Fatigue Behaviour of RTM Composite Cross-joints[J]. Journal of Materials Engineering, 2009, 0(1): 74-76,80.
Fatigue experiments of three kinds of composite cross-joints,processed respectively by using resin transfer moulding(RTM),stitched RTM and co-bonding techniques,were carried out to investigate the influences of processing on fatigue behaviour,and failure mechanism was then discussed from the experimental observation.The results show that the RTM cross-joint has the highest fatigue strength in three kinds of cross-joints and the stitching and co-bonding processes have significant influences on fatigue strength of joints.Experimental observations show that the de-lamination firstly appears at upper angular point in resin-rich triangular zone of tee-joint and then propagates along the interface between resin-rich triangular zone and curved web/flange until the bottom plate,subsequently,grows along the horizontal bottom plate till failure of joint.
JIA Pan-jiang, CHEN Bang-feng. Application of ZL205A High Strength and High-quality Casting in Large Aircraft[J]. Journal of Materials Engineering, 2009, 0(1): 77-80.
This paper systematically summarizes casting characteristic,chemical composition,mechanical properties and application of ZL205A alloy.Some suggestions for ZL205A alloy excellent casting used in large aircraft of China were made.
