最新刊期
卷 ， 期 7 ， 2007
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- 摘要：The semi-solid slurry of AlSi7Mg alloy was prepared by being poured at a low superheat and stirred at a low power electromagnetic field for a short time,and then the slurry was further soaked for proper time and finally rehoformed into a key-shaped die cavity.The influences of slurry temperature,injection specific pressure and injection rate on the rheoforming process were investigated.The results show that the major spherical primary α-Al phase and a little rosette-like primary phase in the AlSi7Mg alloy can be observed with pouring at 630～650 ℃ and stirring by an a low power electromagnetic field for a short time.The primary α-Al phase can be further spheroidized and coarsened as a result of accelerate ripening of primary α-Al phase by soaking treatment at liquid-solid zone for some time.The experimental results reveal that the slurry temperature,injection specific pressure and injection rate have great effects on the filling ability of semi-solid AlSi7Mg slurry,where the higher the slurry temperature,injection specific pressure and injection rate are,the higher the slurry filling ability and the shorter the core distance for the ingate are and the easier the filling of semi-solid AlSi7Mg alloy is.The slurry can fully fill the cavity of key parts with the slurry temperature more than 585 ℃,or the injection specific pressure more than 20 MPa,or the injection rate more than 1.73 m/s.The key parts have uniformly distributed microstructures,showing that the above-mentioned methods can be suitable for producing the semi-solid parts with high quality.关键词：Semi-solid;Electromagnetic Field;Rheo-forming;Microstructure;AlSi7Mg Alloy
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发布时间：2023-12-18 - 摘要：The metallographic etch for as-cast and solid solution treated samples of AZ91D magnesium alloy in sand casting and permanent mould casting has been performed,and as-cast microstructure and ESBD experiment of die casting AZ91D magnesium alloy have been investigated.The results show that the dendrites in as-cast microstructures of sand casting and permanent mold samples are characterized by sixtuple-symmetrical features,in which the angle between the primary dendrites is 60°,and the grain size can coarsen after solid solution.The absence of sixtuple-symmetrical features can be observed as a result of high cooling rate restraining the full growth of dendrites in die casting samples.EBSD experiment can accurately measure the grain size and grain orientation in die casting samples.关键词：AZ91D Magnesium Alloy;Metallographic Etch;Dendrite;EBSD
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发布时间：2023-12-18 - 摘要：The inner pressure creep behaviors of advanced Zr alloy M5TM and N36 with similar microstructure have been measured,and their textures have been observed by XRD.The effects of testing stress on creep mechanism have been approached based on experimental data.The equation of creep rate via normalization stress has been established by taking the yield stress of the alloys as normalization values in the testing conditions,which can fully respond the effects of texture on the inner pressure creep behavior in the condition of the abort of creep power function.关键词：Zr Alloy;Texture;Inner Pressure Creep
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发布时间：2023-12-18 - 摘要：The ignition-proof time of the magnesium powder with 0.2～1.0 mm in size prepared by electromagnetic vibration atomizing and quenching has been examined at 1 000 ℃.The results show that the ignition-proof time of rapidly-solidified magnesium powder keeps for 17～21s while that of milling-passivated magnesium powder keeps for 11～14 s.The morphology of the rapidly-solidified magnesium powder was observed by SEM and EPMA.It is found that the C-enrichment on the surface of the magnesium powder can be observed.The chemical stability of powder surface can be strengthened to lead to the passivation effects due to the formation of compact surface during rapid solidification.关键词：Electromagnetic Vibration Atomizing;Quenching;Magnesium Powder;Passivation
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发布时间：2023-12-18 - 摘要：The influences of nano-carbon particle concentration in bath,current density,temperature and stirring method on the properties of electro-deposited Cr-C composite coating have been investigated.The surface morphology and phase structure of the coating were analyzed by scanning electronic microscopy（SEM） and X-ray diffractometer（XRD）,and its micro-hardness was determined by micrometer.The results indicate that the black Cr-C composite coatings with compact and uniformly distribution structure can be generated by adjusting the processing parameters,where the maximum micro-hardness can reach 10.8 GPa and maximum particle volume fraction in the coating can reach 8.82%.The optimized processing parameters for electro-depositing composite coating are as follows:current density of 100 A·dm-2,temperature of 15 ℃ and nano-carbon concentration in bath of 10 g·L-1.In addition,ultrasonic disperse was used to assist slowly mechanical stirring.关键词：Electro-deposition;Black Cr-C Nano-composite Coating;Microstructure;Micro-Hardness
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发布时间：2023-12-18 - 摘要：SiC/Al-5.3Cu-0.8Mg-0.6Al-0.5Mn heat resistant aluminum matrix composites with volume fraction of 50% SiC were prepared by squeezing-infiltration method.The effects of high volume fraction SiC particle on the microstructure and mechanical properties of the alloy have been investigated.The results show that high volume fraction SiC particle can greatly improve the aging hardening and tensile strength of the composites,where the tensile strength of the composites can be increased from 356 MPa to 520 MPa with peaking aging at 185 ℃.The SiC/Al-5.3Cu-0.8Mg-0.6Al-0.5Mn heat resistant aluminum matrix composites possesses a compact and uniformly distributed microstructure,and its fracture mode is characterized by the boundary separation,toughness fracture of the matrix and particle crack.Although the high volume fraction SiC particle can not affect the aging precipitation process of the matrix alloy,in which the precipitate is composed of Ω phase and minor θ’ phase,the interfacial reaction between SiC particle and matrix alloy can be observed to create nano-scale Al4C3 phase.关键词：Heat Resistant Aluminum Matrix Composites;SiC Particles;Microstructure;Mechanical Properties
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发布时间：2023-12-18 - 摘要：An ERP management information system for investment casting enterprises was developed including order,sale,production,stock,human resource and customer relationship and so on,based on the investigation of present investment casting enterprise management mode on production and the analysis of management problems in the enterprise combining with management procedure and current ERP idea.The ERP system offers a set of resolution map for investment casting enterprises,obtaining desirable effects by applying into some enterprises.关键词：Investment Casting Enterprise;ERP;Application
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发布时间：2023-12-18 - 摘要：A numerical calculation based on phase field method was developed to describe two-dimensional solidification and evolution of the interface morphology as well as the effects of phase field parameters on pure matter using succinonitrile.The results show that with increasing anisotropy values,the cell can be evolved into developed dendrites gradually,while the nuclei can be grown into the cell with γ of 1/15.With increasing undercooling rate,the second dendrite occurs in the structure and grows,where the tip velocity at steady state becomes faster and faster;with the increase of coupling coefficient,the tip velocity at steady state can be improved,however,the interfacial stability can be decreased.关键词：Phase Field;Succinonitrile;Dendrite Growth;Tip Velocity
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发布时间：2023-12-18 - 摘要：A thermal-mechanical model was developed to describe semi-solid thixo-forging process with high solid fraction,including temperature field,maximum/minimum temperature distribution,moving speed of the mould as well as forming force.The simulated results reveal that occurrence of conventional hot-forging can be observed during thixo-forging,meanwhile,high forging speed can decrease forming force,which can result in the liquid-solid phase separation in the billets.The simulated maximum forming force is well in agreement with experimental one,showing the availability of the model,however,there exists the difference in forming force during thixo-forging,which means the model need be further optimized.关键词：Semi-solid Thixo-forging;Model;Temperature Field;Forming Force
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发布时间：2023-12-18 - 摘要：The thixo-formed A356 alloy parts were investigated by micro-defects analysis,mechanical properties testing and numerical simulation.The results reveal that the appearance and distribution of defects in parts were seriously affected by the state of fluid field during filling to deteriorate the mechanical properties.The defects in the parts can be greatly reduced to improve the mechanical properties by optimizing the fluid field in the thixo-forming process.关键词：Semi-solid;Thixo-forming;Filling;Defects;Simulation
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发布时间：2023-12-18 - 摘要：The wear resistance of hot work steel DIEVAR,DAC and self-developed TFHS-1 for magnesium die casting were examined by GWY-2000 high temperature wear tester.The results indicate that the oxidation wear is dominant in wear mechanism at a high temperature of 550 ℃ in the condition of dry abrasion,meanwhile minor adhesion wear and abrasive wear in the abrasive mechanism can be observed.The wear properties of TFHS-1 steel are superior to that of DIEVAR and DAC steel.In addition,the wear properties of TFHS-1 steel can be obviously improved with increasing tempering temperature,showing great effects of heat treatment on wear properties at an elevated temperature.关键词：High Temperature Wear;Oxidation Abrasion;Hot Work Steel;Magnesium Alloy Die Casting
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- 285
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发布时间：2023-12-18 - 摘要：Aluminum alloy motor enclosure with super-high rotating differential rate has been produced by low pressure casting.Horizontal four opening mould structure and main core vertical upper-opening mould structure were adopted in the mould.In addition,an opening gating system was designed,in which the ingate was set at the position of 45°with side-prating surface.The liquid aluminum alloy was poured at 680～720 ℃ and the lower-mould and side-mould were preheated at 300～350 ℃ and 250～300 ℃,respectively.Constant-pressure automatic control system was employed for liquid surface pressure-applying device,meanwhile,quenching and artificial aging were used.The mechanical properties of the enclosure are obviously superior to those required in the nation standard through above mentioned ways.关键词：Enclosure;Mould;Low Pressure Casting;As-cast Quenching
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- 131
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发布时间：2023-12-18 - 摘要：The structure characteristics and the operating principles of the die casting die with rotating cross direction core for thread demoulding by rack and spur gear transmission were described,in which one-mould-twin-cavities structure were adopted.The mould was designed to use open force transferred by rack and spur gear mechanism rotating cross direction core for thread demoulding.The rack is fixed outside the template of the die casting machine,so the length is free from the restriction of thickness of the die casting die,simplifying the die structure and reducing the size of the die.The mould is compact in structure and credible and easy in operation,exhibiting high product efficiency and the accuracy of parts produced.关键词：Automatic Thread Demoulding;Die Casting Die;Rack and Spur Gear Mechanism;Rotating Cross Direction Core
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发布时间：2023-12-18 - 摘要：The investment shell mold was made of polyethylene wax and colloidal silica.The production verifies that it is an available method to make sol silica shell mold with polyethylene wax,providing a new approach for reducing pollution and decreasing the making cost as well as spreading the sol silica shell mold and producing high quality investment castings.关键词：Investment Casting;Polyethylene Wax;Sol Silica Shell Mold
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发布时间：2023-12-18 - 摘要：The quantitative analysis of crack in guide blade of high pressure turbine for an engine was conducted by MEF4A image analyzer,SEM quanta 400 and EMPA.The crack characteristics in the guide blade of high pressure turbine were determined by observing macro-morphology and fracture morphology of crack as well as microstructure of the blade.The origination of crack was analyzed also.关键词：Turbine Blade;Crack;Microstructure
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发布时间：2023-12-18 - 摘要：There exist slag hole,gas hole and shrinkage porosity in nodular iron steering knuckles for micro-car in shell mold casting with middle-pouring gating system.Through enlarging exhausted channel and the size of gating and runner system,adjusting pouring direction of liquid Fe into cavity and selecting proper nodular agent,raw Fe for nodular iron and auxiliary materials,the qualified rate of the castings can be increased from about 50% to more than 85%.关键词：Steering Knuckle;Nodular Iron;Shell Mold
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发布时间：2023-12-18 - 摘要：A mould with new gas film definition for aluminum alloy in continuous casting was designed,in which the gas film was formed between mould and initial solidified shell,which can decrease the transverse heat transfer in the mould to form approximately single direction heat transfer condition in the billets and to decrease the liquid front depth and to shorten the length of initial solidified shell to eliminate the inner defects in aluminum alloy ingot and to improve the quality of the ingot.The numerical simulation of heat transfer in new mould and conventional mould has been conducted,showing that the remarkable change of temperature field can be observed in the new mould.The continuous casting 7075 aluminum alloy billets with smooth surface can be produced with new mould in the condition of stability and balance of gas film.The relationship of drawing velocity and gas flux with gas pressure as well as their effects on the billet quality have been described.The stability of gas film can be controlled by gas flux in the condition of a constant liquid surface height.关键词：Continuous Casting;Aluminum Alloy;Mould;Gas Film Definition;Billet Quality
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- 112
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发布时间：2023-12-18 - 摘要：Aiming at the structure features of large copper screw nut with 8.9 tons in weight,the brass screw nut with high strength was successfully manufactured for rolling machine of Nanjing Steel Company through strictly controlling chemical composition in the screw nut and using rotating speed of 870～925 r/min,and pouring at 1 040～1 080 ℃ as well as cooling with water.关键词：Brass with High Strength;Large Screw Nut;Centrifugal Casting
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发布时间：2023-12-18 - 摘要：In-situ TiC particle reinforced ZA70 composites have been fabricated by adding the Al-Ti-C powder blocks into molten aluminum ZA70 alloy.It was found that the co-presence of brittle Al3Ti flakes with TiC particles is observed in the composites with melting at 900 ℃,while the presence of TiC particles can be only observed in ones with the melt temperature increased to 1 300 ℃.Occurrence of TiC particles can improve the strength at room and high temperatures and slightly deteriorate the elongation of the composites.However,the formation of Al3Ti flakes can weaken the strengthening effects of TiC particles.关键词：In-situ Synthesis;TiC/ZA70 Composites;Microstructure;Mechanical Properties
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发布时间：2023-12-18 - 摘要：Al3Ti particles reinforced Al matrix composites have been prepared by in-situ SHS synthesis in 5Al-Ti system.The reaction mechanism and therodynamics of 5Al-Ti powder blocks were described,and effects of processing parameters on microstructure of the composites were investigated.The results reveal that in-situ Al3Ti particles can be created at 850 ℃ in 5Al-Ti system,which exhibits fine blocks and short rods and uniformly distributes into the Al matrix.The hardness of the composites can be increased with the increase of Al3Ti particles content.In addition,the rational stirring way is beneficial for the uniform distribution of the Al3Ti particles in the composites.关键词：In-situ Synthesis;Al3Ti Particles;SHS;Aluminum Matrix Composites
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- 404
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发布时间：2023-12-18 - 摘要：The Al-Ti-B-RE master alloy was prepared with K2TiF6,KBF4,Al-10RE by in-situ synthesis.The optimized element compositions,namely 5% Ti,1%B,0.5%RE,were optimized by an orthogonal testing.The morphology of TiAl3 phase in the master alloy exhibits blocks with small size,and uniformly distributes into the master alloy.The grain size in the A356 aluminum alloy with the master alloy treated is 25.7% of that of un-treated alloy,in which the distance from dendrites are evidently dropped,showing the refining effects of the Al-Ti-B-RE master alloy superior to that of Al-5Ti-B master alloy.关键词：Al-Ti-B-RE Master Alloy;Refiner;Composition Optimization;Grain Refinement
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- 254
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发布时间：2023-12-18 - 摘要：AZ91D magnesium alloys were processed by micro-arc oxidation（MAO） in silicate solution by means of a self-designed AC（alternative current） power suppler.The optimized processing parameters of MAO for AZ91D magnesium alloy in silicate solution were determined on the basis of an orthogonal testing with four factors and three levels used to systematically investigate the coating thickness,surface roughness and corrosion resistant.The results show that the MAO film is characterized by porous structure and smaller apertures and compact film layer as well as uniform distribution in the surface of the AZ91D magnesium alloy,consisting of MgO,Mg2SiO4,AgAl2O4 and minor SiO2,in the condition of the optimized processing parameters.The absence of apparent pit-erosion in the film surface can be observed after immersing for 168 h in 3.5% NaCl solution at room temperature,demonstrating the corrosion resistance greatly superior to that of AZ91D magnesium alloy substrates.关键词：AZ91D Magnesium Alloy;MAO;Silicate Solution;Morphology;Corrosion Resistance
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发布时间：2023-12-18 - 摘要：The Al-Ti-C master alloy was prepared with K2TiF6,graphite powder and pure aluminum by in-situ reaction method.Microstructure of the master alloy was observed by OM（optical microscope）,SEM（scanning electron microscope） and EPMA.The results show that the bulk Al3Ti phase can be observed with the addition of K2TiF6,graphite powder at the same temperature,while the needle or long strip Al3Ti phase can be observed at different addition temperatures.In addition,the TiC particle exhibits different synthesized mechanism with different adding temperature of K2TiF6,graphite powder关键词：Grain Refiner;Microstructure;Synthesized Mechanism
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发布时间：2023-12-18 - 摘要：Microstructure and electro-chemical properties of Mg-Sr anode were investigated.The results indicate that the grain size in the Mg-Sr anode can be decreased with the increase of Sr content.The current efficiency and open potential of the anode will reach the peak value of 58.56% and-1.735 Vsce with 0.19% Sr content,while the current efficiency will be decreased and the open potential will be shift positively with the Sr content more than 0.19%.Microgalvanic cell can be formed from Mg17Sr2 phase segregated from boundary and α-Mg phase with 0.19% Sr content,which can inhibit the intergranular corrosion and reduce the grain spallation as well as relieve the deterioration effects of Fe phase to lead to the improvement of current efficiency and the positive shift of open potential as a result of refining grain size and enlarging grain boundary area as well as more uniform inclusion phase distribution.With the Sr content more than 0.19%,excessive Mg12Sr2 phase can increase the self-corrosion rate of the anode,resulting in the decrease of current efficiency and positive shift of open potential.关键词：Mg-Sr Anode;Microstructure;High Potential;Electro-Chemical Properties
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发布时间：2023-12-18 - 摘要：The closed-pore aluminum foam was manufactured by direct foaming with blowing gas into the molten aluminum,and the effects of the processing parameters on the pore structure and the stability of aluminum foam were investigated.The aluminum foam with mean pore size and more than 90% porosity can be manufactured by means of Al-Si alloy as raw materials and Al2O3 particles as adhesion agent with foaming temperature at 750～780 ℃ and particle volume fraction of 10%～15% as well as gas flux at 0.5～1.5 L/min.The production verifies that the gas injection foaming is a promising method to produce aluminum foam with high porosity simply and efficiently.关键词：Aluminum Foam;Gas Injection Method;Pore Aperture;Stability
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- 342
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发布时间：2023-12-18 - 摘要：Effects of self-spin of liquid copper in mould on microstructure and mechanical properties of hollow copper pipe have been investigated.The results reveal that the change of flow ways of liquid copper can evidently refine the grain size and improve the distributed uniformity of solidified structure.With the improvement of solidified structure,the average tensile strength and elongation of the hollow copper pipe billets can be increased by 9.7% and 36.5% respectively.关键词：Self-spin;Copper Pipe Billets;Solidification Structure;Mechanical Properties
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发布时间：2023-12-18 - 摘要：Yunnan variegated copperware is a unique folk art in the Yunnan province.The key processes to produce variegated copperware are described,and the effects of alloy components,materials of cast mould and emergent and coloring agent on the variegated pattern were paid attention to.The factors influencing the variegated copperware were presented.The results demonstrate that the desirable variegated pattern can be observed with 6% Zn content in the variegated copperware.The irregular variegated pattern can be formed in sand mold casting while particle variegated pattern can be observed in the permanent mold.In addition,the variegated copperware is almost independent on the emergent and coloring agent.关键词：Art Foundry;Variegated Copperware;Variegated Pattern;Emergence;Coloring
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发布时间：2023-12-18 - 摘要：Effects of Zr on glass forming ability and thermal stability of Fe-Al-Ga-P-C-B-Si amorphous alloy have been analyzed by XRD and DSC.The experimental results reveal that the alloy retains amorphous features with Zr content less than 2.0%（atom percentage）.Although the DSC curve had no obvious glass transition,the XRD observation indicated that the alloy with 1% Zr content（atom percentages）,which is attributed to the exothermic peak of initial crystalline phase,had blanketed glass transition.DSC curves of the alloy with 0.5% and 2% Zr contents presented apparent glass transition temperature and wider undercooled liquid region,respectively,and the position of crystalline exothermic peak shifted towards higher temperature area,which reveals that the alloy have high glass forming ability and thermal stability.In addition,the thermal stability was verified by the parameters γ.关键词：Fe-based Amorphous Alloy;XRD;DSC;Glass Forming Ability（GFA）;Thermal Stability;Crystalline Phase
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发布时间：2023-12-18 -
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