LIU Hui-min, REN Yun, LIU Jun, YAO Qing-hu. Grain Growth of in-situ Reactive Liquidus Cast Al Alloy at Semi-solid State[J]. Journal of Materials Engineering, 2006, 0(1): 3-7,11.
The microstructures of in-situ reactive liquidus cast 7075+X%(volume fraction)TiC((X=0,0.5,1.2,2.5))Al alloys at semi-solid state were observed using SEM.The grain sizes were measured using a mean linear intercept method and the effect of in-situ TiC particles on grain growth in the two-phase(liquid+solid)region of liquidus cast 7075 Al alloy was analyzed.The result shows that the in-situ TiC particles can not only keep liquidus cast 7075 Al alloy with fine and globular microstructure,but also control evidently grains growth by pinning effect during reheating.
FAN Ying-wei, YE Yang, HOU Shu-e, SONG Jin-xia, HAN Ya-fang. Effect of Carbon Content on Microstructure of IC6 Alloy[J]. Journal of Materials Engineering, 2006, 0(1): 8-11.
The microstructure of alloy IC6 with different carbon contents as-cast and after homoginization at 1260℃ for 10h was studied by SEM with EDS and XRD.The results showed that the microstructure of as-cast alloy was mainly composed of γ',γ,NiMo,α-Mo,M3B2 and M6C phases.NiMo,α-Mo,M3B2 and M6C phases distributed in the interdendrite in bone or net pattern.Quantity of NiMo,α-Mo and M3B2 phases decreased obviously with increase of C content,and α-Mo phase disappeared when C content reached 0.20%(mass fraction),while the amount of M6C increased with increase of C content.Microstructures of the three alloys changed obviously after 1260℃/10h solution heat treatment,and NiMo,α-Mo phases disappeared.The shape of M3B2 and M6C transformed from bone and net pattern in as-cast to strip and block pattern.Quantity of M6C increased obviously with increase of C content,distributing continuously in the interdendrite.
WU Yi, ZOU Zheng-guang, YIN Chuan-qiang, LI Xiao-min, ZHOU Lang. Thermodynamics on Steel-bonded Cemented Carbide GT35 by in-situ Carbothermic Reduction Form Ilmenite[J]. Journal of Materials Engineering, 2006, 0(1): 12-15.
Steel-bonded cemented carbide GT35 was fabricated by reaction sintering technology,using mineral ilmenite containing iron and titanium elements as the raw material.Synthesis and sintering were accomplished unanimously in the vacuum resistance furnace.A new way to synthesize the GT35 composite with relative low cost was practiced.The thermodynamics of the FeTiO3-C system was studied in detail through thermal analysis.The results showed that carbothermic reduction happened in the FeTiO3-C system,followed by the deoxidation of ilmenite step by step via a series of different valent titanium oxides to get TiC and iron solid solution as the ultimate phases.The experimental research confirmed that the interface bonding of GT35 was good and its structure was also compact.
LIU Wei-wei, TANG Ding-zhong. Effect of Withdrawing Rate on Solidification Microstructure of Single Crystal Superalloy DD6[J]. Journal of Materials Engineering, 2006, 0(1): 16-18.
The effect of withdrawing rate on the solidification microstructure of a single crystal superalloy DD6 was investigated.The results show that,with the increase of withdrawing rate,the morphology of liquid-solid interface of DD6 alloy transforms from coarse dendrite to fine dendrite,the size of the γ' phase particles decreases,the shape of γ' particles tends to be more cubic,the volume fraction of γ-γ' eutectic increases and the volume fraction of coarse primary γ' precipitates in γ-γ' eutectic decreases.
ZHANG Zhao, CHEN Jin-tao, ZHANG Hong-wu. Scale Effect of Pin on Friction Stir Welding[J]. Journal of Materials Engineering, 2006, 0(1): 19-23,31.
Finite element method was used to study the material behavior and the residual stress distributions during the friction stir welding process.The results show that the flow of the material in the tangent direction takes the main contributions to the movement of the material in the friction stir welding process.A fluidized bed of material flow comes into being around the pin.With the increase of the pin’s diameter,the laminar flow becomes much easier to be observed. The maximum of the longitudinal residual stress occurs in the boundary of the heat affected zone.The double peak feature of the longitudinal residual stress can be found.The region of the large residual stress becomes wider when the diameter of pin is increased.
LI Jin-ping, HAN Jie-cai, LI Qing-fen, MENG Song-he, ZHANG Xing-hong. Study of Two-phase Particle Softening HfB2 Composites[J]. Journal of Materials Engineering, 2006, 0(1): 24-26,65.
The two-phase particle softening HfB2 composites were prepared by means of mixing and hot-pressing.Their compressive properties,hot expansion coefficient, ablation resistance and the microstructure were studied.The results showed that the compressive properties of the HfB2 composites at room temperature were finer,while those at high temperature decreased sharply.With the temperature increased,the volume expansion ratio increased gradually;the average linear expansion factor hardly changed;while the instant linear expansion factor decreased first,and then raised,there was a minimum value.It was 5.65×10-6/K at 900℃.After the HfB2 composites had been ablated on the plasma-arc heater for 8s,the partial softening particles of the composites were melted and spurted,remaining holes.
LIU Ping, PANG Xiao-hui, YANG Jun-hong, LIU Xiao-yan, LI Guo-hua. Investigation on Apply of Spectroscopic Chromatic-dispersion-power[J]. Journal of Materials Engineering, 2006, 0(1): 27-31.
The investigation was carried on spectroscopic line-chromatic-aberration.The experience formulas were given to calculate the line chromatic aberration power of spectroscope.The research results of this work can be used to determine the corresponding relation between spectrum and adjustment knob.The experience formulas can meet the requirements of determining spectrum line.The experimental results agreed well with the calculated values.
ZHANG Bao-fa, RUAN Hong-wu, LI Dong-sheng. C/C Composite as Observed by Polarized Light[J]. Journal of Materials Engineering, 2006, 0(1): 32-34.
Various types of deposited carbon textures can be identified by the appearance under optical microscopy with cross-polars.The extinction angle of the deposited carbon in C/C composite can be measured by rotating the analyzer.The problems encountered during the observation by polarized light microscopy are listed.The method to measure the extinction angle is also introduced.In addition,the recently research results on pyrocarbon anisotropy is briefly presented.
PAN Lei, TAO Jie, CHEN Zhao-feng, LIU Zi-li. Acoustic Effect of High Intensity Ultrasonic in Particles/Metal Melt[J]. Journal of Materials Engineering, 2006, 0(1): 35-37,42.
The mechanism and effective range of the high intensity ultrasonic(20kHz,1kW)in the SiCp/ZA27 melt at 600℃ were discussed and analyzed.It is shown that the maximum of the local instantaneous high press and high temperature caused by acoustic cavitation can be 105MPa and 1.77×104K.The effective intensity of the acoustic stream is different in every part of the melt.In order to obtain prime composites,it must be ensured that every part of the melt is treated by high intensity ultrasonic.The preparation mechanism of SiCp/ZA27 composites with homogeneously dispersing reinforced particles and prime interface under high intensity ultrasonic treatment is the result of the cooperative effects of acoustic cavitation and high speed acoustic stream in melt.
ZHONG Xiang-yu, BAO Jian-wen, CHEN Xiang-bao, LI Ye. Study on Toughness and Dielectric Property of Modified Cyanate Ester Resin[J]. Journal of Materials Engineering, 2006, 0(1): 38-42.
Morphology of the modified cyanate ester resin system toughened by polyetherimide was investigated.Impact resistance and dielectric performance of the modified resin system were characterized and analyzed.The results show that polyetherimide can not only toughen this resin system,but improve the dielectric performance.The dielectric performance of the modified resin system is remarkably influenced by the concentration of catalysis,the cure temperature and toughening agent.
CHENG Xiu, JIE Xiao-hua, CAI Lian-shu, LU Guo-hui, XIE Guang-rong. Microstructure and Properties of Ni-P-SiC(Nanometer)Electroless Composite Coating[J]. Journal of Materials Engineering, 2006, 0(1): 43-46,56.
The Ni-P-SiC(nanometer)composite coating was prepared by the electroless depositing.The effect of the content of the nanometer SiC particles on the microstructure and properties was discussed.The results showed that depositing rate increased by adding proper nanometer SiC particles in the solution.The reason was that the liquid-solid interface increased,so the effective activating area increased.For the nanometer SiC in the film,the coating hardness increased.The hardness of the film reached 1000～1100HV before annealing and could reach 1650HV after annealing.The wear resistance of the nanometer coating increased comparing with the micrometer composite coating.The crystallizing rule of the film was analyzed by DSC and the crystallizing temperature increased greatly.
ZHANG Guang-cheng, GU Jun-wei, DONG Shan-lai, ZHANG Qiu-yu, KONG Jie, TANG Yu-sheng, LI Ying. Preparation and Mechanism Analysis of Intumescent Flame-retardant Coatings[J]. Journal of Materials Engineering, 2006, 0(1): 47-52.
An intumescent flame-retardant coating was prepared using the determinated unsaturated polyester resin and epoxy resin as matrix resins,ammonium polyphosphate,melamine and pentaerythritol as flame-retardant assistants,by adding fillers and other assistants.Results show that such a coating has good physical-chemical properties.Under the thickness reaching 2.0mm,it is found that the limit of fire-endurance can get to 210 minutes.Differential scanning calorimentry(DSC)and thermo-gravimetric analysis(TGA)were used to analyze the various components’ thermal characteristics of flame-retardant coating system.The heating decompose course and interaction of different component are studied.The shape of char-layer burned is observed by Photo and scanning electric microscope(SEM)apparatus.X-ray diffraction(XRD)is also used to study the clay-layer structure.On this base,the form of char-layer and the flame-retardant mechanisms of intumescent flame-retardant coating were systematically investigated.
JIN Yong-ji, SHAO Tian-min, YIN Liang, GAO Xue-ning. Investigation on Surface Nitridation of Titanium by Pulsed Laser[J]. Journal of Materials Engineering, 2006, 0(1): 53-56.
Surface nitridation of titanium was induced by pulsed laser irradiation in nitrogen atmosphere.The nitridation layers were characterized by scanning electron microscope(SEM),X-ray diffraction(XRD)and Raman spectroscopy.XRD results showed that the main phases of the nitridation layers were α-Ti and δ-TiN,with a small amount of α-Ti(N).With the increase of laser average power,δ-TiN and α-Ti(N)content in the nitridation layers increased.Correspondingly,the nitrogen content also increased.The hardness and Young’s modulus of the nitridation layers were measured by nano-indentation with a load of 2mN and found to be 11.5~15GPa and 200~250GPa,which were much higher than that of titanium.
WANG Xiao-feng, SHAN Ping, HU Sheng-sun, WU Zhi-sheng. Mechanism of Effect of Deep Cryogenic Treatment on Microstructure of Cr-Zr-Cu Alloy for Electrode[J]. Journal of Materials Engineering, 2006, 0(1): 57-60.
The variations of microstructure of Cr-Zr-Cu alloy before and after deep cryogenic treatment(DCT)were observed and analyzed by means of optical microscope,TEM,XRD and so on.The mechanism of the effect of deep cryogenic treatment on microstructure of the alloy was discussed.The results showed that Cr,Zr particles dispersively precipitated from the matrix,the twin structures emerged during deep cryogenic treatment and there were changes of diffraction peak intensity of some crystal planes(i.e.texture)in Cr-Zr-Cu alloy under long-time cryogenic treatment.The grain preferred orientation was sufficiently corroborated by XRD results of Cr-Zr-Cu alloy before and after cryogenic treatment.
WU Guo-song, ZENG Xiao-qin, GUO Xing-wu, YAO Shou-shan. Application of Vapor-deposition Coatings on Magnesium Alloys Surface Modification[J]. Journal of Materials Engineering, 2006, 0(1): 61-65.
Properties,development of preparation technology of vapor-deposition coating and its application on magnesium alloys surface modification were reviewed.The recent study of protective coatings deposited on magnesium alloys by PVD and CVD technology was introduced.It also shows that vapor-deposition coating is a good substitute for traditional galvanic coating and has a great prospect in application in the future.
