最新刊期
卷 ， 期 1 ， 2008
- 摘要：The densification of multi-layer co-deposited large dimensional 7090/SiCp composites was performed by extruding casting.The effects of extruding process on the microstructure and properties of the composites and on the densities of as-deposited and as-extruded composites were described.The results reveal that pores in the composites are elongated to gradually close as a result of co-action of heavy hydrostatic pressure and shearing stress during extruding process,taking a positive densification effect.The distribution of SiC particles in the extruded composites was obviously improved due to its broken during extruding process.And the tensile strength of as-extruded composites is 540 MPa in transverse direction and is 325 MPa in longitude direction after heat treatment.关键词：Extruding Process;Multi-layer Co-deposition;SiCp/7090 Composites;Densification
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发布时间：2023-12-18 - 摘要：The effects of the types of oxide ceramic moulds and particles size of oxide ceramics as well as heating power on surface roughness of Ti50Al alloy specimens were examined in the condition of electromagnetic field,and the formation mechanism of surface roughness was approached.It is found that under electromagnetic filed,the orders of surface roughness of Ti50Al alloys prepared in five kinds of ceramic moulds are as follows:Ra（Al2O3）>Ra（CaO）>Ra（ZrO2,CaO）>Ra（ZrO2,Y2O3）>Ra（Y2O3）.Meanwhile,the surface roughness of Ti50Al alloy specimens is declined with decreasing in particle size of refractory and heating power.关键词：Electromagnetic Field;Surface Roughness;Ti50Al Alloy;Interface Reaction
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发布时间：2023-12-18 - 摘要：The penetration of magnetic field and cooling effects in two-stage mold and in slit mold for soft-contact electromagnetic continuous casting were compared through a numerical simulation method.The results show that（1）the magnetic flux density in two-stage mold is decreased with the frequency increasing,while the magnetic flux density in slit mold is increased with frequency increasing.（2）the penetration of magnetic field is increased and cooling effects are decreased in two-stage mold with increasing in the length of top half of mold,while that in slit mold is increased with increasing in numbers,width and length of slit.（3）although the penetration of magnetic field in both molds are equivalent,the uniformity of magnetic field and electromagnetic pressure in two-stage mold is superior to those in slit mold.（4）the cooling effects of both molds are similar,and the thickness of initial solidified shell in slit mold is thinner about 0.32 mm than that in two-stage mold.关键词：Soft-contact Electromagnetic Continuous Casting;Electromagnetic Metallurgy;Two-stage Mold;Slit Mold;Electromagnetic Field
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发布时间：2023-12-18 - 摘要：Pure Al-based foam materials were fabricated by melt direct foaming.Solidification characteristics of foam!materials were described in the condition of air cooling and forced water cooling.The results reveal that the solidification of pure Al-based foam materials was characterized by laminated solidification at outer foam and by volumetric somidification at inner foam,which leads to the formation of crack in center axial of aluminum foam,in case of air cooling,while it was characterized by laminated solidification under forced water cooling condition,so the absence of crack can be observed due to the uniform distribution of porosity in the foam.Based on an established solidification model for pure Al-based foam,it is found that solidification contraction can be uniformly distributed throughout the cell walls during laminated solidification,eliminating the crack formed from partial solidification of cell walls and homogenizing the distribution of porosity in the foam.关键词：Melt Direct Foaming;Pure Al-based Foam;Solidification Process;Air Cooling;Forced Water cooling;Defects
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发布时间：2023-12-18 -
Effects of Boron on Microstructure of 6009 Aluminum Alloy Prepared with Electrolytic Low Ti Aluminum
摘要：Effects of Al-B master alloy on microstructure of 6009 aluminum alloy prepared with commercial pure aluminum and with electrolytic low Ti aluminum have been investigated.The results indicate that the refinement effect of Al-B master alloy on 6009 aluminum alloy prepared with commercial pure aluminum can be neglected,however,the refinement effects of it on that prepared with electrolytic low Ti aluminum is significant.The desirable refinement effects on the alloy prepared with electrolytic low Ti aluminum can be observed with 0.05% Ti content at the ratio of 1∶5 for B/Ti,however,the grain size in the alloy obviously becomes coarse at the ratio of 1∶2.22 for B/Ti.And the grain size can be decreased gradually with the increase of B content.关键词：Al-B Master Alloy;Electrolytic Low Ti Aluminum;Grain Refinement- 2
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发布时间：2023-12-18 - 摘要：The bonding strength and interface morphology of pure Ti that is plated TiSiN film with different Si content by the magnetron sputtering method and Solidex were investigated by AGS materials testing machine and EMPA（electron microscope probe analysis）.Variance analysis reveals that the bonding strength of TiSiN plated pure Ti and Solidex is superior to that of the pure Ti and the Solidex,furthermore,the bonding strength can be increased with increasing in Si content in TiSiN film.The compact amorphous TiN and SiNx phase can be generated in the film and be filled into the porosity between the metal matrix and Solidex light-cured hard crown and bridge composites,which is helpful for preventing the leakage of metal ion from the film,so the bonding strength is improved.关键词：Pure Ti;Magnetron Sputtering;Film-plated;TiN;Light-cured Hard Crown and Bridges Composites;Bonding Strength
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发布时间：2023-12-18 - 摘要：Effects of electromagnetic filed frequency in the range of 5 kHz to 40 kHz on magnetic induction density have been analyzed by carrying out three dimensional numerical simulations on magnetic field in electro-magnetic soft-contact continuous casting mold with the finite element software ANSYS.The results indicate that the magnetic induction density in the region of molten steel in mold can be increased with the increase of electromagnetic field frequency.Whereas,with the frequency more than 20 kHz,the increase of magnetic induction density becomes to be neglected.The frequency change has a little effect on the location of maximum value of magnetic induction density at the surface of billets along the height direction of mold which occurs in about 5-6 mm below the top surface of molten steel.However,the increase of electromagnetic field frequency can enhance the non-uniformity of magnetic induction density along circumference.The optimized value of electromagnetic field frequency is 20 kHz.关键词：Electromagnetic Soft-contact Continuous Casting;Electromagnetic Frequency;Magnetic Induction Density Distribution;Numerical Simulation
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发布时间：2023-12-18 - 摘要：The flow morphology in melt filling in thin-walled aluminum alloy plate was simulated in low pressure casting.Furthermore,the effects of filling pressure,lift velocity and cavity thickness on filling behavior in low pressure casting were approached,and the processing parameters were presented,which provided a reference to precisely control the process of low pressure casting.关键词：Low Pressure Casting;Numerical Simulation;Thin-Walled Castings;Lift Velocity;Filling Pressure
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发布时间：2023-12-18 - 摘要：The visualization of filling!of air-conditioner housing for automobile was conducted by the JSCAST software on the basis of establishing a 3D model combining with practical technology.The simulated results,which are well in agreement with practical production,show that the shrinkage（porosity）would occur in the junction of inlet and housing where the change of thickness is sharp,and the absence of air gas entrapment could be observed due to smoothly filling.The defects at the above mentioned locauion can be effectively eliminated by setting gate at the junction to strengthen feeding effect and by shortening the length of core to optimize the structure of housing,and so on.The results show that the computer visualization can optimize the scheme to improve the quality of the housing.关键词：JScast Software;Squeezing Casting;Air Conditioner Housing for Automobile;Shrinkage Porosity
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发布时间：2023-12-18 - 摘要：The AZ91D magnesium alloy engine brackets in JH70 motorcycle was produced successfully with the pressing machine on the basis of billets prepared by decreasing pouring temperature combining with die casting.The results indicate that the microstructure of the brackets with compact structure is composed of primary α-Mg phase and eutectic phase which consists of net-like secondary α-Mg phase and γ-Mg17Al12 phase.The hardness and tensile strength of T4 treated components are decreased by 4.5% and by 3.1%,respectively,while those of T6 treated ones are increased by 30.1% and by 14.0%,respectively,and elongation of the components treated by T4 and by T6 is increased by 17.6% and by 40.5%,respectively,compared with that of ones without treatment.关键词：Semi-solid;AZ91D Magnesium Alloy;Thixo-forming;Microstructure;Mechanical Properties
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发布时间：2023-12-18 - 摘要：The effects of weak power on the morphology of α-Al phase in slurry and radial distribution of microstructure of slurry which was prepared by low super-heating pouring and weak electromagnetic stirring have been observed.The results indicate that the AlSi7Mg alloy slurry with 127 μm in diameters and uniformly distributed microstructure in which fine spherical primary α-Al phase is generated can be prepared successfully with pouring at 630 ℃ and stirring power of 0.36 kW in the condition of low super-heating pouring and weak electromagnetic stirring.Meanwhile,the morphology of primary α-Al phase can be further spheroidized with the increase of stirring power,however,it has been little improved with the stirring power increase to a certain value.The microstructure of semi-solid AlSi7Mg alloy slurry is converted from dendrite into rosette-like structure into spherical structure from edge to center of slurry in radial direction.关键词：Semi-solid State;AlSi7Mg Alloy;Slurry;Primary α-Al phase
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发布时间：2023-12-18 -
Microstructure of Hypoeutectic High Cr Cast Iron Prepared by Slope Plate with Different Flute Radius
摘要：Effects of slope plate flute radius on the appearance of pre-eutectic austenite in the semi-solid slurries of hypoeutectic high chromium cast iron prepared by self-developed slope plate with 100 mm and 400 mm flute radius have been observed.It is found that,compared with that of pre-eutectic austenite in the slurry prepared by slope plate with 100 mm flute radius,the average shape coefficient and roundness are obviously improved and average equivalent diameter is decreased with somewhat increasing in solid fraction of it prepared in the condition of 400 flue radius,obtaining the hypoeutectic high Cr cast iron with non-dendrite austenite.关键词：Hypoeutectic High Cr Cast Iron;Semi-solid Slurry;Slope Plate Flute Radius;Pre-eutectic Austenite- 2
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发布时间：2023-12-18 - 摘要：The fatigue crack propagation behavior of AZ91HP alloy was observed and the fatigue fracture structure as well as crack propagation mechanism was described in the condition of as die-cast（F）,solid solution treatment（T4）and solid solution plus aging（T6）treatment.The results reveal that the fatigue crack propagation behavior of the alloy is strongly dependent on the value of stress intensity factor（△K）,in which with decreasing △K,the fatigue fracture becomes more and more smooth,and in turn with the increase of △K,the fracture becomes rougher.The plasticity-induced crack closeness effects were observed in the process of fatigue crack propagation,which can result in the increase of the value of crack-opening stress intensity factor（Kop）and the decrease of effective stress intensity factor（△Keff）.The crack propagation rate was inversely proportion to the plasticity of AZ91HP alloy.Because the plasticity of the alloy was increased in T6,F,T4 sequential order,the crack propagation rate was decreased in T6,F,T4 sequential order.关键词：Die Cast Magnesium Alloy;Fatigue Fracture;Crack Propagation
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发布时间：2023-12-18 - 摘要：Microstructure and mechanical properties of BH22 piston alloy in squeezing casting have been investigated.It is revealed that the eutectic Si phase in microstructure of squeezing casting BH22 alloy is characterized by the coarse bar or block,which is different from acicular structure in gravity-casting BH22 alloy.In addition,the amounts of creation of Al9FeNi phase in the alloy can be observed in squeezing casting.Compared with those of gravity die casting ones,the tensile strength and hardness of squeezing casting BH22 piston alloy can be increased evidently,reaching up to 300.3 MPa and HB120,respectively.关键词：Squeezing Casting;Al-Si Alloy;Piston;Eutectic Phase
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发布时间：2023-12-18 - 摘要：The tensile strength and elongation of hot extruded Al-Si-Cu-Mg alloy at room temperature can reach 296.6 MPa and 18%,respectively,showing significant improvement of mechanical properties of the alloy.Eutectic phase and secondary phase,including Al2Cu phase and Mg2Si phase,in the hot extruded Al-Si-Cu-Mg alloy can be converted from bulk particle or short rod into fine particles with more uniform distribution.After T6 treatment,the tensile strength of the alloy can reach 408 MPa with elongation more than 10%,which is attributed to the spheriodization of Si particle eliminating the stress concentration during tensile testing.关键词：Al-Si-Cu-Mg Alloy;Hot Extrusion;Microstructure;Fracture
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发布时间：2023-12-18 - 摘要：Compared with large stainless steel valve body in sand casting,it was difficult to control solidification process in investment casting,which results in some defects in the valve body.Through adjusting the composition and thickness of mold shell and improving the feeding system as well as controlling pouring process,the shrinkage porosity（hole）can be effectively eliminated in the valve body in investment casting,obtaining qualified valve body.关键词：Valve Body;Investment Casting;Sand Casting
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发布时间：2023-12-18 - 摘要：By introducing ZrO2（4Y）powder into the thermit,Al2O3/YSZ composite ceramic plates were prepared through combustion synthesis under high gravity,and microstructure and mechanical properties of the composite ceramics were investigated.The eutectic in-situ composite ceramics consist of the Al2O3 matrix colonies in which t-ZrO2 submicron fibers are embedded,surrounded by the boundary region with t-ZrO2 and Al2O3 irregular particles,and the hypoeutectic ceramics are composed of Al2O3 grain surrounded by ZrO2 bands due to the divorced eutectic growth while the hypereutectic ceramics are mainly made up of fine isolated t-ZrO2 spherical grains.Vickers hardness of the eutectic composite ceramics were reached up to the maximum value of 16.7GPa due to high residual stress in the colony matrix and fine boundary regions of eutectic colony,while fracture toughness can reach up to 14.6 MPa·m1/2 in the hypereutectic composite ceramics due to toughening mechanism involving stress induced t-ZrO2 transformation toughening and transformation induced by micro-crack toughening.关键词：Al2O3/YSZ Composites Ceramics;Combustion Synthesis;High Gravity;Crystal Growth;Structure Transformation
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发布时间：2023-12-18 - 摘要：Aluminum matrix hybrid composites reinforced by SiC hollow porous foam and SiC particles with different sizes,including 7 μm,15 μm,20 μm,were fabricated by squeezing casting.The effects of SiC particle sizes and aluminum matrix toughness on the compressive strength and flexural strength of the composites have been examined.It is found that with the increase of SiC particle size,the compressive strength and flexural strength as well as maximum deflection of the composites are decreased,which is attributed to the increase of SiC particle size leading to the increase of the space between particles to result in the deterioration of strength of SiC particle.With the improvement of the aluminum matrix toughness,the plastic deformation is obviously increased and compressive strength as well as elastic modulus is decreased.关键词：Hybrid Composites;Particle Size;Mechanical Properties;Matrix Toughness
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发布时间：2023-12-18 - 摘要：The variation of hydrogen content in magnesium alloy scraps before and after purification treatment by Ar2 degassing and effects of hydrogen content on microstructure and mechanical properties of the alloy have been examined by self-developed quantitative hydrogen-measuring equipment for liquid magnesium and quantitative metallographic method.The results indicate that the hydrogen content in the magnesium alloy scraps can be decreased by 40% with Ar2 purification.Although the micro-porosity in the degassed scraps is reduced greatly,it is higher than that in magnesium alloy ingot at the same conditions.In addition,the density of degassed alloy is obviously improved,and the tensile strength and elongation are increased by 19% and by 63%,respectively,compared with the alloy scraps before degassing treatment.关键词：Magnesium Alloy Scrap;Micro-porosity;Hydrogen Content;Degassing;Mechanical Properties
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发布时间：2023-12-18 - 摘要：The spheroidizing effects of Ce on Fe（Si）-rich impurity phase,and its effects on the mechanical properties and the erosion resistance of commercial pure aluminum were investigated by microstructure observation,tensile strength testing,inert erosion resistance as well as SEM and EDS analysis.The results reveal that Ce can spheroidize Fe-rich phase from coarse Chinese script into fine spheroid and create high point intermetallic compound containing Fe and Si impurity.The tensile strength and elongation of commercial pure aluminum with Ce modification were improved by 44.18% and by 32.04%,respectively,with erosion resistance raising by 220%,compared with that of aluminum without Cr modification.关键词：Commercial Pure Aluminum;Fe（Si）-rich Impurity Phase;Ce;Spheroidizing Effects
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发布时间：2023-12-18 - 摘要：Effects of solution treatment on microstructure of as-aged AZ80 magnesium alloy have been observed by OM（optical microscope）,XRD（x-ray diffraction）and SEM（scanning electron microscope）.The results show that the microstructure has the important effects on precipitate mode,number and morphology of β-Mg17Al12 phase with aging at 200 ℃ after different solid-solution treatment.The discontinuous precipitation is dominated in precipitate,and major precipitate occurs in the incomplete solution alloy with aging for 4 hours.With aging for 12 hours,the continuous precipitation is dominated in the complete solution alloy,which can restrain the nucleation and growth of discontinuous precipitates at grain boundary,while the precipitates in the incomplete solution alloy are still controlled by discontinuous precipitation,in which partial precipitates invade into α-Mg phase.关键词：Solid Solution;Magnesium Alloy;Aging Treatment;Microstructure
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发布时间：2023-12-18 - 摘要：Effects of Sr modification and electromagnetic stirring on grain morphology and size of primary phase in AZ91D magnesium alloy have been described.It is found that Sr can refine the grain size in the alloy from 500 μm to 372 μm,however,the refinement effects is sharply faded with the increase of Sr addition.Meanwhile,the grain in Sr modified AZ91D magnesium alloy becomes more fine uniform spheroidal particles with size about 72 μm after electromagnetic stirring.The analysis of refining mechanism shows that the blended role of Sr modification with electromagnetic stirring is superior to modification or electromagnetic stirring only.关键词：AZ91D Magnesium Alloy;Al-10Sr Master Alloy;Melt Treatment;Electromagnetic Stirring
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发布时间：2023-12-18 - 摘要：The ignition temperature of ZM5 magnesium alloy can be increased greatly by adding mischmetal（MM）composed of La and Ce element,increased to more than 800 ℃ with 0.1% MM addition,obtaining desirable ignition-proof effects.The surface morphology of oxidized film of ZM5-0.1RE alloy was observed by optical microscope（OM）.The results reveal that the compact film is composed of RE2O3,MgO,Al2O3 and Mg17Al12 with densification degree more than 1,exhibiting excellent protection performance.The oxidation kinetic curves of the alloy is accordant with the parabola principle at 700 ℃,which is controlled by diffusion,showing good oxidation resistance.关键词：Mischmetal（MM）;Ignition-Proof Magnesium Alloy;Oxidization Film;Oxidation Kinetics
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发布时间：2023-12-18 - 摘要：Microstructures of the Al-20Si-5Fe alloy perform and sprayed-form powder prepared by spray forming technology were observed by OM（optical microscope）,SEM（scanning electron microscope）and XRD（x-ray diffraction）.The formation mechanism of Fe-rich phase in Al-20Si-5Fe alloy during spray forming was analyzed by microstructure observation of sprayed form powder and perform.The formation of short rod-like Fe-rich phase in the perform is resulted from the fracture of acicular Fe-rich phase during deposited process.关键词：Spray Forming;Hypereutectic Al-Si Alloy;Fe-rich Phase;Deposition Process;Solidification
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发布时间：2023-12-18 - 摘要：Mg-based alloy Mg80Zn16-xCa4Cux（x=2,4,6）with 2mm in diameter was prepared by means of copper mold casting based on the design of amorphous alloy composition forming rule.The microstructure,phase constituent and compressive behavior of the as-cast alloy were investigated by SEM（scanning electron microscope）,XRD（x-ray diffraction）and mechanical property testing device,and the fracture morphology of alloy was analyzed.The density of the alloy was obtained by using the Archimedes law and the specific strength was calculated.The Mg80Zn16-xCa4Cux alloy with x of 2,4,6 is 574.5,678.6,616.7 MPa in compressive strength,respectively,and 449.7,300.8,389.8 MPa in yield strength,respectively and 1.1%,4.6% and 4.0% in elongation,respectively,in which the Mg80Zn12Ca4Cu4 alloy has the highest both in strength and in plastic deformation in rare earth free Mg-based alloy reported up to now.关键词：Mg-Zn-Ca-Cu Alloy;Microstructure;Mechanical Properties
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发布时间：2023-12-18 - 摘要：Effects of annealing treatment on oxidation rate of Cu-1.0Al alloy at high temperature were investigated by SEM,EPMA and SIMS.The results reveal that the oxidation resistance of the alloy at high temperature is greatly strengthened as a result of the creation of Al2O3 film in the surface with annealing at H2 atmosphere,which is improved obviously due to forming more sound Al2O3 film and more strenghened bonding with the matrix with increasing annealing temperature and decreasing the cooling rate.The desirable oxidation resistance of alloy can be presented with annealing at 900 ℃ and cooling at 0.6 K/min.关键词：Cu-Al Alloy;Annealing;High Temperature Oxidation;Al2O3
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发布时间：2023-12-18 - 摘要：The Cu-Ni-Cr alloy strip was produced by medium frequency furnace smelting and iron mould casting,and then hot rolling,then solid solution and aging treatment.Effects of different heat treatment specifications on microstructure and properties of the alloy have been examined by tensile testing,electric conductivity measurements,optical microscope and transition electron microscope observation.The results reveal that the pre-cold deformation and sub-structure strengthening resulting from aging as well as the precipitating strengthening of Cr particles precipitated from supersaturated solid solution are responsible for the high strength of the alloy.The pre-cold deformation of alloy before aging can greatly improve the strength with the little decrease of electric conductivity.The tensile strength,yield strength,elongation and electric conductivity of alloy are 415.2 MPa,368 MPa,13.2% and 23.89 MS/m,respectively,with 50% cold deformation and then holding for 4 hours at 450 ℃.关键词：Cu-Ni-Cr Alloy;Heat Treatment;Microstructure;Mechanical Properties;Conductivity
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发布时间：2023-12-18 -
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