最新刊期
卷 ， 期 12 ， 2007
- 摘要：Ni-Al intermetallic compounds were prepared with Al powder and Ni powder by SHS（self-propagating high-temperature synthesis）.The thermal explosion curves were mapped,and the reactive process was described.Meanwhile,the mechanism of thermal explosion and the microstructure of products were analyzed,and the boundary conditions as well as the effects of variables on thermal explosion were expounded.The results indicate that the ignition time and temperature of thermal explosion can be declined with increasing heating rate and reducing particle size,in which the ignition temperature of reaction is lower than the eutectic temperature.The thermal explosion of Ni-Al system is induced by solid-solid diffusion reaction,and the reaction product singular NiAl phase of Ni-32Al can be observed.关键词：SHS;Thermal Explosion;Ni-Al Intermetallic Compounds;Reaction Variables
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发布时间：2023-12-18 - 摘要：Rapidly solidified behavior of Cu-10Ag alloy droplets prepared by ultrasonic arc spray atomization was observed by SEM and X-ray.The powder consists of spheroidal particle with size in the range of from 15 to 70 μm and average size of 45μm.The initial cooling rate of alloy droplets can be realized from 105 K/s to 107 K/s.The solidification structure of alloy droplets is composed of Cu-rich cell containing about 7% Ag and cell wall containing 50%60% Ag,exhibiting cellular structure.In addition,the average cell size is decreased from about 2 μm to about 1 μm with the particle size decreasing from 80 μm to 15 μm.The solidification mechanism was analyzed also.关键词：Ultrasonic Arc Spray Atomization;Ag-Cu Alloy;Rapid Solidification
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发布时间：2023-12-18 - 摘要：The Ti-Mo and Ti-Cr alloys were fabricated by tungsten electrode melting and centrifugal casting.The Mo and Cr element on microstructure,mechanical properties and dry friction-wear resistance of Ti alloys have been analyzed.It was found that Ti-Mo alloys are composed of equiaxed β phase,and the effects of Mo addition can be ignored on the refinement of the equiaxed crystal,while Ti-Cr alloys consist of dendrite β phase,and the Cr addition has the positive effects on the refinement of the dendrite.The Ti-Mo alloy is higher than the Ti-Cr alloy in hardness,however lower in compressive strength and compression rate and near in elastic modulus with the same Mo and Cr addition.The minimum stable friction coefficient can be observed in Ti alloys with 20% Mo addition among four kinds alloys.Wear surface of Ti-Mo alloys has deeper furrow while wear surface of Ti-Cr alloy has narrow furrow with amounts of abrasive particles.关键词：Ti Alloy;Microstructure;Mechanical Properties;Dry Friction-wear Resistance
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发布时间：2023-12-18 - 摘要：Effects of holding time on morphology,size and distribution of primary Si in Al-22Si alloy treated by EPM have been described.The results indicate that the solidification structure of Al-22Si alloy has been obviously modified with the melt treated by electric pulse,in which the uniformly distributed primary Si is converted from coarse lath into bulky and its average size is decreased from 153.15 μm to 77.35 μm,however,the inoculation modification is faded with increasing holding time.The structure in the EPM treated alloy is similar with that of no-EPM treated alloy with holding for 80 min,increasing from 77.35 μm to 143.67 μm in average size.关键词：EPM;Primary Phase;Cluster;Inoculation Fading
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发布时间：2023-12-18 - 摘要：The effects of electromagnetic continuous casting on the phase constituent,microstructure and corrosion resistance of magnesium alloy AZ31 were investigated.The results reveal that although the change of phase constituent in electromagnetic continuous casting AZ31 magnesium alloy can not be observed,the grain size in the billet is refined with broken dendrites and uniform continuous β-Mg17Al12 phase distributed around bulk α-Mg phase.Compared with that of the billets in conventional continuous casting,the corrosion rate of AZ31 magnesium alloy billets in electromagnetic continuous casting is decreased by 29.4 % in 5% NaCl salt spray testing,which is attributed to the continuously distributed net β-Mg17Al12 phase effectively controlling the corrosion of Mg alloy.关键词：Magnesium Alloy;Electromagnetic Continuous Casting;Microstructure;Corrosion
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发布时间：2023-12-18 - 摘要：The chemical conversion coating was homogeneously created on the surface of Mg-10Li-1Zn alloy in a phosphate-permanganate solution.Some processing variables,including chemical composition content,temperature and time of the conversion solution,were optimized by orthogonal testing to obtain a desirable constituents and processing.Moreover,the microstructure and chemical composition of conversion coating with Cr free were described.Hydraulic-potential polarization curves show that the phosphate-permanganate conversion coating exhibits better corrosion-resistantance on Mg-10Li-1Zn alloy compared with conventional chromate conversion coating.关键词：Mg-Li Alloy;Conversion Coating;Phosphate-permanganate;Corrosion Resistance
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发布时间：2023-12-18 - 摘要：The morphology and microstructure of powder prepared by spray forming have been observed by SEM（scanning electron microscope）and OM（optical microscope）.Observation reveals that the particle in sprayed powder is spherical or near-spherical with uniform distribution,moreover,the smaller the particle size is,the more spherical the morphology is.Major particles are formed by heterogeneous nucleation and the minor particles are formed by homogeneous nucleation.In addition,the microstructure of sprayed powder is dendritic structure.关键词：Spray Forming;Sprayed Powder;Dendrite;Droplet
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发布时间：2023-12-18 - 摘要：The physical and mathematical model were established based on the principles and heat transfer features of the OCC to investigate the effects of some variables,including cooling distance,pulling velocity and internal-wall temperature in mold,on the position and shape factors of liquid-solid interface during OCC process.The optimized processing parameters and the feature data of liquid-solid interface in the condition of optimized processing parameters were described.The influencing orders of processing parameters on the features of liquid-solid interface were determined,verifying by practical production.关键词：OCC;Numerical Simulation;Liquid-solid Interface Position;Shape Factor
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发布时间：2023-12-18 - 摘要：Parameters influencing rheology behavior of semi-solid magnesium include temperature,strain rate and holding time.Apparent viscosity of the semi-solid magnesium alloy is declined with the increase of shearing rate and heating temperature,however,with the shearing rate more than 5×10-3 s-1,its increase becomes slow gradually.The curves of apparent viscosity to solid fraction of MB15 alloy are different from that of AZ91D due to its grain shape and spheroidization rate,exhibiting slow change.In addition,the apparent viscosity is decreased to keep constant state with increasing in holding time.关键词：AZ91D Magnesium Alloy;Semi-Solid Isothermal Heat Treatment;Deformation Behavior
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发布时间：2023-12-18 - 摘要：The microstructure and properties of semi-solid magnesium alloy billets prepared by extruding casting were described on the basis of the slurry prepared by two-screw stirring method.The results indicate that the primary α phase in the billets exhibits irregular polygonal or rosette structure with the average size of 4565 μm.The finer microstructure can be observed in edge of the billets,which is different to structure in center.The extruding casting can improve the density and hardness of semi-solid magnesium alloy components,compared with conventional squeezing casting,increased by 0.33% in density and by 7.91% in hardness.关键词：Semi-solid;Magnesium Alloy;Extruding Casting;Microstructure;Properties
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发布时间：2023-12-18 - 摘要：Effects of solid solution and aging parameters on properties of semi-solid AlSi7MgBe alloy parts have been examined by orthogonal testing.The processing parameters were optimized based on the measurement of tensile strength.The results show that the parts with desirable mechanical properties including tensile strength of 318 MPa and elongation of 15.24% can be produced with solid solution at 545 ℃ for 4 h and aging at 175 ℃ for 11 h,and the precipitates are dispersively distributed in the matrix.关键词：AlSi7MgBe Alloy;Semi-solid;Thixo-forming;Solid Solution and Aging;Orthogonal Design
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发布时间：2023-12-18 - 摘要：The microstructure of Al-5Ti-1B alloy after equal channel angular pressing with four passes at room temperature was observed by XRD（X-ray diffraction）,OM（optical microscope）and SEM（scanning electron microscope）.It was found that the equal channel angular pressing can improve the mechanical properties of the alloy as a result of refining the grain size and improving the distributed uniformity of secondary phase in the matrix alloy.With increasing in pass,the bulk TiAl3 phase in alloy can be refined from 2080 μm to about 10 μm,and the uneven bulk TiB2 can become more uniform.The yield strength and Vickers hardness of Al-5Ti-1B alloy are increased from 142.0 MPa to 221.4 MPa and from 45.2 to 64.9,increased by 56.1% and by 43.6%,respectively,after four passes equal channel angular pressing based on the Bc routes.关键词：Equal Channel Angular Pressing;Al-5Ti-1B Alloy;Grain Refinement;Mechanical Properties
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发布时间：2023-12-18 - 摘要：High vacuum die casting process as a new techniques and die casting aluminum alloy with high strength and ductility as a new materials are increasingly used to manufacture automobile parts due to tightly lightweight required in developed countries.The hydrogen content in parts can be decreased to 13 mL/100 g due to the vacuum degree up to 9196 kPa in mould cavity in high vacuum die casting process,so the strength and ductility of parts can be improved by heat treatment.Aluminum alloy with high strength and ductility is mainly Al-Si-Mg series alloy,whose mechanical properties is improved by solid solution strengthening of Mg in alloy.The present developing methods to high vacuum die casting process are mainly Vacural method and MFT method,in which MFT method is more suitable for small-scale die casting plants.关键词：High Vacuum Die Castings;Die Casting Aluminum Alloy;Strength;Ductility;Lightweight
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发布时间：2023-12-18 - 摘要：The combination process of die casting with forging is a new forming method,which combines processing features of die casting with forging.Under the condition of the same processing parameters and with the help of orthogonal testing,AZ91D magnesium alloy samples were produced by the combination process of die casting with forging and by conventional die casting,respectively,which are treated by T6.And then,the mechanical properties and microstructure of samples were investigated.The results indicated that compared with that of samples by conventional die casting,the tensile strength and elongation of samples by combination process of die casting with forging are improved by 84.394% and by 101.761%,respectively,moreover,improved by 94.672% and by 121.617%,respectively after T6 heat treatment.Meanwhile,the finer grain size in microstructure can be observed in samples produced by combination process of die casting with forging.关键词：AZ91D Magnesium Alloy;Combination Process of Die Casting and Forging;Die Casting;Processing Parameters
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发布时间：2023-12-18 - 摘要：The basic idea of developing standard-part library was described.Based on the dimension driven parametric modeling method,a standard-part library of squeezing casting die was developed with Solidworks as developing platform,Visual Basic as developing tool and Access database as tool of managing all data of squeezing casting standard parts.The standard parts could be called directly through a simple parameter’s input in the design process.Practice has verified that the system,which has s strong practical significance,is successful in avoiding work cumbersome and shortening the developing period of squeezing casting mould.关键词：Squeezing Casting;Standard-part Library;Solidworks;Parameterization
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发布时间：2023-12-18 - 摘要：Direct shell-making method was adopted in producing narrow flow-channel close impeller to avoid using water-soluble sand core and to reduce production cost.The practical production shows that the shell-mold was poured with sand slurry at inlet and outlet and was poured with dry sand at middle after stuccoing three layers face sand,which not only ensure the quality of the castings to decrease the scraps,but also easily remove the shell-mold sand in flow-channel.关键词：Investment Casting;Impelle;Shell-making
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发布时间：2023-12-18 - 摘要：The origination of eccentricity of a hollow bar castings was analyzed.The formation of eccentricity in the bar castings was attributed to the deflection deformation of core resulting from co-action of floating force and thermal deformation due to irrational gating system.The eccentric defects in hollow bar can be obviously eliminated by modifying gating system.关键词：Investment Casting;Eccentricity;Floating Force;Thermal Deformation
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发布时间：2023-12-18 - 摘要：A new method to cast-in hard alloy on high Cr wear resistant alloy was adopted according to the operating condition of guttering back board.The composites with excellent comprehensive properties can be fabricated by embedding the hard alloy into EPS pattern to pour.The composites exhibit high wear resistance due to the addition of Cr,Mo,W,V into the based alloy and proper composition resulting in the creation of M7C3 carbides with high micro-hardness.In addition,the high impacting roughness can be observed due to the dispersive distribution of carbides in the composites.The hard alloy can greatly improve the red hardness of the back board.The molding,gating system and smelting of back board in lost foam casting were described.Practical trial-use verified that the service life of back board can be greatly improved.关键词：Guttering Back Board;High Cr Cast Iron;Lost Foam Casting;Cast-in
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发布时间：2023-12-18 - 摘要：Effects of melt blended processing on the microstructure and mechanical properties of AZ91 magnesium alloy in lost foam casting were investigated.The results indicated that melt blended processing can refine the microstructure and greatly improve the mechanical properties,such as the tensile strength of the alloy with blending at 720 ℃ increased by 24%,which is obviously superior to traditional high temperature treatment.The refinement of dendrite in the microstructure is attributed to the creation of more nuclei in blended liquid melt during melt blended processing.关键词：Melt Blended Processing;Lost Foam Casting;Magnesium Alloy;Microstructure;Mechanical Properties
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发布时间：2023-12-18 - 摘要：The magnetic field distribution in a traveling magnetic field generator was calculated with ANSYS software,which was well in agreement with the experimental ones.A critical length related to the polar distance of traveling magnetic field was obtained.The traveling magnetic field is independent on the move of liquid alloy with the length of liquid alloy lower than critical length.The six forces were exerted on liquid alloy during filling in traveling magnetic field casting,leading to the flow change from accelerate to constant to decelerate,which be responsible for the formation of defects,such as cold shut,misrun.Two methods to change the distribution of magnetic field were put forward.The ANSYS results show that the two ways can realize the gradient-reduction distribution of magnetic field.关键词：Electromagnetic Casting;Polar Pairs;Filling;Flow Velocity
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发布时间：2023-12-18 - 摘要：The dry wear and friction resistance of Al2O3/Cu composites prepared by internal oxidation method have been examined under the condition of loading.The results revealed that the wear and friction resistance of Al2O3/Cu composites are superior to that of red copper under the same condition.The weight loss of the samples is increased and friction factor is decreased with increasing in speed and loading at a given current.The abrasive and adhesion wear are observed in surface of Al2O3/Cu composites samples,while the adhesion wear in surface of red copper is generated.The weight loss and friction factor of the Al2O3/Cu composites with 0.60% Al2O3 content is lower than that of ones with 0.24% Al2O3 content under the experimental condition.关键词：Al2O3/Cu Composites;Wear and Friction;Weight Loss;Friction Factor;Internal-oxidized Rate
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发布时间：2023-12-18 - 摘要：Solid Solution treatment T4 was carried out on CNTs/ZM5 alloy composites fabricated by stirring casting technology.The effects of CNTs on mechanical properties of the ZM5-T4 matrix composites were examined,and the fracture morphology of the composites was observed by SEM（Scanning Electron Microscope）and energy spectrum analysis.The results reveal that the CNTs can strengthen mechanical properties of the composites.Furthermore,the Ni plating CNTs are better than un-plating CNTs in strengthening effects on the composites,which is attributed to the metallurgical bonding of Ni-plated CNTs with the ZM5 matrix.However,the excessive addition of CNTs would result in the decrease of mechanical properties of the composites due to the generation of segregation.关键词：ZM5 Alloy;CNTs;Composites;T4 Solid Solution Treatment
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发布时间：2023-12-18 - 摘要：The properties of ceramic coating could be improved by adjusting the compositions in electrolyte during microarc oxidation.The effects of RE ion Ce3+ and La3+ addition on microstructure and mechanical properties of ceramic coating on ZAlSi12Cu2Mg1 prepared by micro-arc oxidation were investigated through adding 0.2 g/L Ce3+ and varied La3+ in electrolyte.The results show that the Ce3+ and La3+ addition can greatly improve the quality of the coating.The ceramic coating prepared by micro-arc oxidation in electrolyte with 0.2 g/L Ce3+ and 0.3 g/L La3+ addition is composed of α-Al2O3,γ-Al2O3,Al2SiO5 and amorphous phase,whose thickness and hardness are 157μm,HV 947,respectively.The weight loss of ZAlSi12Cu2Mg1 matrix alloy is 102.2 mg while the weight loss of ceramic coating is 19.7 mg,19% of that of matrix alloy,after 6 000 rads abrasion.关键词：Cast Aluminum Alloy;Micro-arc Oxidation;Ceramic Coating;Ce3+;La3+
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发布时间：2023-12-18 - 摘要：The effects of trace Sr on the as-cast microstructure and mechanical properties of AZ91D magnesium alloy have been investigated by means of SEM（scanning electron microscope）,Hi-scope compact micro-vision system,multi-functional materials experimental machine,Brinell hardness tester and impact testing machine.The results indicate that trace Sr addition can change the β phase in AZ91D magnesium alloy from net-like structure into spheroid or short rod ones.Compared with that of AZ91D magnesium alloy without Sr addition,the tensile strength and elongation of the alloy with 0.05% Sr addition can reach 185.4 MPa and 6.7%,respectively,increased by 11.3% and by 139.3%,respectively,which is related to the change of Sr on morphology of β phase.In addition,the impact toughness of the magnesium alloy is 40.2 J/cm2 and 29 J/cm2 in graphite mold and in sand mold,respectively,improved by 26.4% and by 12.5%,respectively,compared with that of the alloy without Sr.Meanwhile,the hardness of alloy is increased with increasing in Sr addition.关键词：Magnesium Alloy;Microstructure;Mechanical Properties
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发布时间：2023-12-18 - 摘要：Effects of alloying element Mg,Si on hydrogen content in aluminum melt and Ar degassing efficiency were examined.It was found that the both Mg and Si element can remarkably enhance the gas-absorbing tendency of aluminum melt.When Mg element exists in the aluminum melt alone,the hydrogen content in aluminum melt is increased with the increase of Mg content,and Ar degassing efficiency becomes clear gradually.However,the hydrogen content in aluminum melt is higher after Ar degassing.Si addition can obviously decrease the Ar degassing efficiency due to restraining the diffusion of H atom into Ar bubble.The co-existence of Mg and Si elements can not only strengthen the absorbing hydrogen tendency in aluminum melt,but also rise the difficulty of Ar degassing.Even so,a short time Ar degassing still has some effects.关键词：Hydrogen Content;Aluminum Alloy;Si;Mg;Ar Degassing
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发布时间：2023-12-18 - 摘要：Co-Ni nano-alloy was fabricated using NaBH4 as reducer and oleic acid as dispersion agent by liquid reduction method,and its structures,particle features,oxidation behavior and magnetic properties were investigated by XRD,SEM and VSM.The results revealed that the samples are converted from amorphous alloy into crystal alloy after baking at 500 ℃ with N2 atmosphere,in which the particles exhibit spheroid with 35 nm in average size.The Co-Ni alloy with saturation magnetization of 83.7 e mu·g-1 and coercives forces tending to zero possesses higher oxidation-resistant ance and superaramagnetization at room temperature.关键词：Nanometer;Co-Ni Alloy;Fabrication;Characterization
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发布时间：2023-12-18 - 摘要：The composition of Cu-Fe-P alloy（Cu-2.5Fe-0.12Zn-0.03P-0.05Mg-0.05Cr-0.05RE）was designed by micro-alloying method.Microstructure of the alloy was observed by OM（optical microscope）and HRTEM,and tensile strength,elongation and electric conductivity of the alloy were examined.The results reveal that at a given experiment condition,the cold rolled alloy plates after aging at 550 ℃ for 4 h exhibit overages,in which spheroidal precipitates γ-Fe are coarsened with size in range of 50 to 100 nm,and the tensile strength,micro-hardness and electric conductivity of alloy are 482 MPa,161 and 39.7 MS/m,respectively,while the alloy exhibits under-ages after aging at 450 ℃ for 4 h,in which the size of shperoidal precipitates γ-Fe is lower than 20 nm,and tensile strength,micro-hardness and electric conductivity are 417 MPa,139 and 30.4 MS/m,respectively The alloy exhibits peak ages after aging at 550 ℃ for 2 hours and 450 ℃ for 2 hours,in which size of spheroidal precipitates γ-Fe is in range of 20 to 50 nm,and the tensile strength,micro-hardness and electric conductivity of alloy are 510 MPa,168 and 40.6 MS/m,respectively.关键词：Cu-Fe-P Alloy;Lead Frame;Aging
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发布时间：2023-12-18 - 摘要：Effects of different cold-rolled deformation rates on super-elasticity and microstructure of TiNiCr shape memory alloys have been investigated by tensile testing and optical microscopeom.Experimental results indicate that the super-elasticity of TiNiCr shape memory alloys can be increased with increasing in cold deformation rate,however,itsincerease can be ignored with the cold deformation rate more than 33%.In addition,totally non-linear super-elasticity of the alloy can not be obtained in the condition of cold deformation.A martensite variant can be created in the TiNiCr shape memory alloys during cold deformation,whose volume would be increased with the increase of cold deformation rate when the cold deformation rate is more than 27%,and whose dislocation is increased with the increase of cold deformation rate.关键词：TiNiCr Shape Memory Alloys;Super-elasticity;Cold Deformation;Martensite
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发布时间：2023-12-18 -
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