最新刊期
卷 ， 期 6 ， 2008
- 摘要：Fe（64-x-y）Ni1Al5Ga2P9.65B9.6Si3C5.75SnxCoy（x=0,0.5,1.0;y=0,0.5,1,1.5,2.5,3.5）amorphous alloys have been prepared by water cooled copper mold,and the glass forming ability（GFA）of the amorphous alloy was examined by XRD and DSC.The results indicate that although the GFA of the amorphous alloy can not be improved with alone adding Co or Sn,it can be improved by adding 0.5% Co and 0.5% Sn（in atom percentage）.Furthermore,although the GFA of the amorphous alloy can be further increased with the increase of Co and Sn addition,however,it will be weakened with adding Co content more than 1.5% and Sn content more than 0.5%.The desirable GFA of the amorphous alloy can be obtained with 1.5% Co addition and 0.5% Sn addition,in which the glass transition temperature（Tg）,the crystallization temperature（Tx）,the under-cooled liquid region（△Tx）and the value of GFA parameters are 696.3 K,782.1 K,85.8 K and 0.413,respectively.关键词：Fe-based Amorphous Alloy;GFA;Mixing Enthalpy;Mixing Entropy
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发布时间：2023-12-18 - 摘要：The microstructure of cross wedge rolled 6061 aluminum alloy was observed.The results indicate that the soft mechanism of the 6061 aluminum alloy exhibits dynamic recovery and the average strain rate is in range of 110 s-1 in the process of cross wedge rolling.The relationship between meta-crystalline size and z parameters is determined by SEM analysis combining with strain rate at different strains,providing a reference to forming aluminum alloy.关键词：6061 Aluminum Alloy;Dynamic Recovery;Meta-crystalline;Cross Wedge Rolling
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发布时间：2023-12-18 -
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- 摘要：The factors influencing Mg segregation layer thickness and ways controlling Mg segregation layer thickness were described by analyzing origination of Mg segregation in 5182 Al-Mg alloy.Mg segregation layer thickness can be controlled in 1.52 mm by adopting LHC mould with double-water-exhausted pore to enhance the cooling rate and cooling water volume at 98 m3/h at initial stage and increasing linearly 239 m3/h at working stage to ensure the match of cooling rate with drawing velocity as well as controlling height of liquid metal at 40mm.
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发布时间：2023-12-18 - 摘要：Crystallization behavior of bulk Cu50Zr42Al8 amorphous alloy during continuous temperature-increment was described.The results indicate that with increasing in the temperature,the glass transformation temperature（Tg）,crystallization temperature（Tx）and crystallization peak temperature（Tp）tend towards high temperature zone,and under-cooled temperature zone △Tx is enlarged.The glass transformation activation energy Eg,crystallization initial activation energy Ex and crystallization peak activation energy Ep are calculated by the Kissinger formula which is 417.19 kJ/mol,332.18 kJ/mol and 327.70 kJ/mol,respectively.In addition,crystallization activation energy Ex is calculated by the FWO equation.It is found that the crystallization activation energy is decreased with the increase of crystallization degree,in which the activation energy is sharply declined with the crystallization degree lower than 5%.The Cu50Zr42Al8 bulk amorphous alloy exhibits desirable thermal stability.关键词：Bulk Amorphous Alloy;Crystallization;Activation Energy
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发布时间：2023-12-18 - 摘要：The laser cladding of Fe-based alloy with different content of WC including 0,2.5%,3.5%,4.0%,4.5% and 5.0%,on a 45 steel substrate has been performed by a laser with automatic powder feeding system.The microstructure,micro-hardness and wear resistance of the coating have been investigated by means of scanning electron microscope（SEM）,electron probe micro-analysis（EPMA）,X-ray diffraction（XRD）,micro-hardness tester and wear testing.The results indicate that the WC addition mainly change the interdendrite of the coating and form W2C phase.The hardness and wear resistance of the Fe-based alloy can be greatly improved as a result of the generation of amounts of finer particle with appropriate WC content.关键词：Laser Cladding;Microstructure;Wear Resistance
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发布时间：2023-12-18 -
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- 摘要：The physical simulation of melt flow of continuous casting aluminum alloy slab with 1 650 mm in length and 220 mm in width in mould was conducted by PIV（particle image velocity）,and the melt characteristics in the mould was described.Five different floating distributors were made with PVC plates whose density is less than that of water to simulate the floating state as practical production.The results show that with the increase of casting speed,free surface tends towards more unstable.Appropriate increase of port angle of floating distributor can increase the stability of free surface.Ports at the bottom can effectively increase the stability of free surface as a result of weakening fluctuation of flow field,reducing oxidation inclusion.关键词：Continuous Casting;PIV;Physical Simulation
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发布时间：2023-12-18 -
Numerical Simulation of Filling Process of Semi-solid A356 Aluminum Alloy in Rheo-diecasting Process
摘要：An apparent viscosity model for the semi-solid A356 aluminum alloy has been established to simulate the filling process in the rheo-diecasting,and experimental validation of the rheo-diecasting has been carried out.The simulated results are well in agreement with experimental ones,showing the availability of the model.The results indicate that the filling of semi-solid A356 aluminum alloy in the rheo-diecasting is closely dependent on the injection pressure,the flow velocity of the slurry at the ingate and the forming temperature.The higher injection pressure and higher flow velocity as well as the higher forming temperature are helpful to the filling of the slurry.In addition,the larger size of ingate is beneficial for the filling of the slurry also.The desirable filling process can be obtained with injection pressure more than 30 MPa at filling velocity of 3.00m/s and pouring at more than 595 ℃.关键词：Semi-solid;A356 Aluminum Alloy;Die Casting;Numerical Simulation- 2
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发布时间：2023-12-18 - 摘要：Thixo-squeezing and thixo-forging of Mg-Al-Zn alloy semi-solid billets prepared by new SIMA method were carried out.Preparation and thixo-forming characteristics of Mg-Al-Zn alloy semi-solid billets were understood by OM（optical microscope）and tensile testing machine.The results reveal that microstructure of the Mg-Al-Zn alloy can be greatly refined as a result of desirable strain induction effects by equal angular extrusion（ECAE）in new SIMA method,in which average grain size of 20μm can be obtained and which are responsible for the obvious improvement of mechanical properties of the alloy.The spheroidized fine grain with average size of 25μm in the microstructure with uniform distribution of the semi-solid billets can be prepared by ECAE with holding at 560 ℃ for 20 min.Thixo-squeezing and thixo-forging experiment verify that the mechanical properties of the thixo-forming Mg-Al-Zn parts can be improved greatly,and the yield strength,tensile strength and elongation of thixo-squeezed satellite angle frame are 213.1 MPa,312.6 MPa and 15.2%,respectively,while those of thixo-forged magazine plate are 218.6 MPa,320.9 MPa and 14.8%,respectively.
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发布时间：2023-12-18 - 摘要：In order to improve and to optimize the performance of the equipment for the preparation of semi-solid slurry by melt spreading and mixing method,a series of experiments have been conducted to observe the effects of some processing parameters including melt temperature,degree of melt spreading,temperature of slurry-making chamber and melt injection on the microstructure of Al-6.56 Si alloy.The results reveal that the four factors have affected the under-cooling degree and temperature distribution of melt.The spheroidized fine microstructure with dispersive distribution can be prepared by controlling melt temperature less than 650 ℃ and rotating speed of spreading machine at 7001 000 r/min as well as temperature of making-chamber less than 300 ℃ and melt injection at in range of 6 kg/min12 kg/min.关键词：Semi-solid Slurry;Melt Spreading and Mixing Method;Microstructure
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发布时间：2023-12-18 -
- 摘要：The MB2 magnesium alloy profile bar with high strength and plasticity which was modified by Re and some special elements was prepared by extruded forming at 330 ℃.Effects of modification elements on microstructure and properties of the Mg alloy profile bar before and after deformation was observed by optical microscope（OM）,image analysis system and MTS-810 materials testing system.The results reveal that the morphology of β-Mg17Al12 phase is converted from the continuous net-like structure into dispersive particles and the grain size is decreased from 100200 μm to 1535 μm in the modified magnesium alloy.The grain size of the modified MB2 magnesium alloy after deformation is further refined to 510 μm,and tensile strength and elongation are remarkably increased from 247 MPa and 13% to 312 MPa and 22%,respectively.
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发布时间：2023-12-18 - 摘要：Prevention and elimination ways of typical defects in squeezed aluminum alloy castings were approached by analyzing the origination and features of the defects.Sequential solidification of liquid metal from far-end to ingate and from key location to non-key location should be ensured as possible in design of squeezing casting and mould.The refinery and degassing of liquid metal should be strictly controlled to avoid the excessive hydrogen-absorption in holding.Slowly filling velocity should be adopted as possible to ensure the smooth filling of liquid metal and to restrain air-entrapped.The near eutectic alloy should be selected in squeezing casting process.The lower squeezing forces should be adopted as possible under the condition of ensuring sound microstructure.The holding time of liquid metal in holding furnace should be strictly controlled,and so on.关键词：Squeezing Casting;Aluminum Alloy;Quality Management;Defect Prevention
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发布时间：2023-12-18 - 摘要：The movement and forces characteristics of double-toggle clamping mechanism in die casting machine were investigated including the relationship of geometry size and position of double-toggle clamping mechanism with mould plate stroke and its speed as well as the amplification ratio of clamping forces.The formulas for calculating the clamping stroke and the cylinder stroke and for estimating the amplification of clamping forces have been derived based on the movement principle of mechanism.The results reveal that the ratio of clamping stroke & cylinder speed and the amplification of clamping forces,which are two important factors of clamping mechanism,are closely related to the geometry dimension and position of double-toggle mechanism.关键词：Die Casting Machine;Clamping Mechanism;Movement Characteristics;Force Characteristics
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发布时间：2023-12-18 - 摘要：Microstructure and mechanical properties of Mg-8Al-xNd alloy with different Nd content prepared by EVO.53D cold chamber press at room and elevated temperature were investigated by an optical microscope and tensile testing.The results indicate that the microstructure of die cast Mg-8Al alloy with the precipitation phase can be refined with Nd addition.The highest tensile strength and yield strength can be examined with 0.5% Nd content.Tensile strength and elongation of the die cast Mg-8Al alloys can be increased by more than 10% and by more than 43%,respectively,with adding Nd after tensile testing at 150 ℃.关键词：Die Cast Magnesium Alloy;Nd;Microstructure;Mechanical Properties
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发布时间：2023-12-18 - 摘要：The present status,future and developing strategy of die casting industry in Chongqing were surveyed.There were die casting machine more than 1050 with the production volume of die castings more than 320 000 tons in 2007.The die casting industry in Chongqing will be increasingly developed with a higher velocity with the development of motorcycle,automobile and communication industry.Die casting enterprises should build R&D center to meet the demand from the market.In addition,the enterprises should establish quality control system and improve the management level,and so on.关键词：Die Casting Industry;Present Status;Future
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发布时间：2023-12-18 - 摘要：Effects of rotating magnetic field on solidified structure of Sn-Bi alloy have been observed based on applying field at different solidified stages.The experimental results reveal that creation of primary phase in Sn-55Bi hypoeutectic alloy is controlled by rotating magnetic field,in which the spheroidized primary Sn phase is uniformly distributed in the matrix.The microstructure with uniform distribution of Sn-65Bi hypereutectic alloy can be observed only with applying rotating magnetic field at the whole solidification process.关键词：Rotating Magnetic Field;Sn-Bi Alloy;Solidification;Dendrite Fragmentation;Gravity Segregation
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发布时间：2023-12-18 - 摘要：The production of thin-walled complex WE54 magnesium alloy parts was carried out with ceramic mold shell by different casting methods.The results show that there exists cold shut,flow line,shrinkage porosity（hole）in the gravity casting thin-walled complex magnesium components due to its low filling ability,while the components with smooth surface and distinct profile as well as high dimensional precision and defect-free can be produced by low pressure casting.The mechanical properties of the low pressure casting magnesium alloy components treated by solid solution are significantly improved,in which the tensile strength and yield strength as well as elongation of the heat treated components are 272.6 MPa,205.29 MPa and 0.99%,respectively,which is attributed to the precipitation of dispersive fine MgY phase from the supersaturated solution phase.关键词：WE54 Magnesium Alloy;Investment Casting;Gravity Pouring;Low-pressure Casting
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发布时间：2023-12-18 - 摘要：Effects of micro-wave frequency and equivalent thickness of plaster mold on micro-wave drying process have been approached,and which was co mpared with that by conventional oven drying process.The results show that the increase of micro-wave frequency can increase the rate of loss water and shorten drying time.Although the equivalent thickness of plaster mold has somewhat effects on drying time,it has greatly effect on the rate of loss water of plaster mold.The rate of loss water of plaster mold can be fasted with the increase of equivalent thickness.It is need about 1.5 hours for drying plaster mold by microwave to 100% loss water rate while it is need about 30 hours by conventional oven drying method.The drying efficiency of microwave is improved by 20 times,however,the tensile strength of the plaster is lower than that by conventional oven drying.关键词：Micro-wave;Plaster Mold;Drying;Casting
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发布时间：2023-12-18 - 摘要：The presence of shrinkage porosity in investment casting was simulated by an CAE/CAD software.The shrinkage porosity in investment castings can be reduced by partial cooling and partial holding temperature to form sequential solidification.In addition,the shrinkage porosity（hole）can be eliminated by strengthening cooling rate on thick-location of castings and feeding channel.关键词：Flange;Cooling;Holding;Sequential Solidification
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发布时间：2023-12-18 - 摘要：Dynamic target temperature fuzzy neural network controller and dynamic temperature neural network controller were designed for a introduced secondary cooling dynamic control system in casting slab from a factory based on the neural network,fuzzy control method combining with PSO algorithm.Based on above results,a secondary cooling water dynamic online learning fuzzy neural network control system（LFNC）has been developed which can dynamically control target temperature and secondary cooling water according to variation of steel types,pulling velocity and super-heating degree under the condition of meeting metallurgical criteria to obtain the low temperature gradient at the front stage of secondary cooling and to fluctuate in range of 6 ℃ at straightening stage,improving the quality of the slab and reducing the secondary cooling water.The intelligent control system has the advantages of small calculation and good stability.关键词：Continuous Slab Casting;Secondary Cooling;Neural Network;Fuzzy;Control
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发布时间：2023-12-18 - 摘要：In-situ steel matrix composites were fabricated by a casting method.The microstructure and effects of loading on high speed wear behavior of in-situ steel matrix composites were investigated by MMS-1G high speed disc wearing tester,SEM and EDS.The results indicate that the in-situ steel matrix composites with uniformly distributed fine and round in-situ carbide particles that can reach up to about 31% in volumetric fraction can be prepared successfully.The wearing rate of the composites is increased from 0.99×10-6 g/m to 4.2×10-6 g/m with the increase of loading from 50 N to 150 N at 40 m/s,however,the frictional coefficient of the composites is decreased with increasing in loading.Finally,the wear mechanism of the in-situ steel matrix composites was approached.关键词：In-situ Steel Matrix Composites;Microstructure;High Speed Drying Sliding Wearing;Wearing Behavior
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发布时间：2023-12-18 - 摘要：Aiming at warping distortion of TC11 Ti alloy blade during hot working process,the isothermal adjustment method was used to relief the warping distortion to improve the microstructure and mechanical properties of the blade by reducing the residual stress,realizing the qualification of the blade dimension.The results reveal that the profile tolerance and mechanical properties as well as microstructure of the TC11 Ti alloy blade with isothermal adjustment before solution plus aging treatment are greatly superior to those of ones with isothermal adjustment after solution plus aging treatment.Desirable microstructure and mechanical properties of the TC11 Ti alloy blade with isothermal adjustment before solution treatment,which exhibits uniform microstructural distribution and clean metallic line profile,can be obtained with adjusting pressure of 3 MPa for 3 min at 860 ℃ and at strain rate of 10-2 s-1.
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发布时间：2023-12-18 - 摘要：The densification mechanism and phase transition of porous Zr based getter alloy prepared by powder metallurgy during vacuum sintering were described.The results reveal that Zr content in the alloy is decreased and Al3Zr5 phase content is obviously increased with increasing in sintering temperature and in holding time,resulting in the increase of activation temperature of the getter alloy.With sintering temperature lower than 1 000 ℃,solid sintering is dominated in sintering process with low volumetric contraction.With the sintering temperature more than 1 000 ℃,the volumetric contraction is sharply decreased due to the presence of minor liquid phase,resulting in the decrease of porosity.The porosity rate can be obviously increased with increasing in pore-forming agent.In addition,with increasing in sintering temperature,the contraction rate is gradually declined.关键词：Getter Alloy;Densification;Phase Transition
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发布时间：2023-12-18 - 摘要：Effects of Ti/Al ratio on microstructure and tensile strength of Ti-46.5Al-2.5V-1.0Cr alloy have been investigated.The TiAl alloy samples with 100 mm in length and 65mm in width and 10mm in height were prepared with ISM（induction suspending melting）and centrifugal pouring.The results reveal that the columnar grains in the microstructure of TiAl alloy can be obtained with the Ti/Al ratio equal to 1.032 and 1.075,and microstructure of the TiAl alloy with Ti/Al ratio of 1.075 is more regular with more remarked orientation in α2/γ lamellar.Microstructure of the TiAl alloy that is composed of full lamellar structure is converted into equiaxed grain with the T/Al ratio of 1.121.Tensile testing reveals that the tensile strength and elongation of TiAl alloy is improved to 600 MPa and to 1.0%,respectively,with Ti/Al ratio decreasing from 1.075 to 1.032,while the tensile strength is decreased to 440 MPa with Ti/Al ratio increasing to 1.121.关键词：Cast TiAl Alloy;Ti/Al Ratio;Lamellar Structure;Tensile Properties
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发布时间：2023-12-18 - 摘要：Effects of electromagnetic field on the cooling curve and solidification structure of Al-Si alloy were described.The cooling curves of alloy in horizontal continuous casting were measured.The results indicate that with alternative electromagnetic field,the initial solidification temperature of the alloy can be increased from 645 ℃ to 656.4 ℃,narrowing the temperature interval,and the solidification time is shortened.In addition,the solidification structure of Al-Si alloy can be evidently refined with exerting electromagnetic field,which is more and more refined and homogenized with the increase of exciting current to 120A.However,the solidification structure can be coarsened with exciting current increasing to 120 A.关键词：Horizontal Continuous Casting;Alternative Electromagnetic Field;Al-1Si Alloy;Cooling Curves;Solidification Structure
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发布时间：2023-12-18 - 摘要：A392 alloy with P-RE mixed modification was investigated by SEM（scanning electron microscope）and XRD（X-ray diffraction）,focusing on morphology and distribution of RE element in A392 alloy as well as refinement mechanism on primary Si phase.It is revealed that the primary Si phase can be obviously refined with 0.5%1.5% RE and P mixed modification,in which the average grain size of primary Si phase reaches up to 19.4μm with 0.08% P and 1.1%RE mixed modification.The RE element can enrich on the growth interface of silicon crystal to restrain the diffusion of Si in alloy melt and to increase the undercooling rate,resulting in destroying the stability of growth interface,which can be responsible for the refinement effects of RE on primary Si phase.However,excessive Re element can result in generation of amounts of RE-enrichment,which can not only be detrimental to the refinement effects on primary Si phase,but also deteriorate the mechanical properties of the alloy.So,the RE content in P-RE mixed modification should be strictly controlled.关键词：A392 Alloy;P-RE Mixed Modification;Refinement of Primary Si Phase
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发布时间：2023-12-18 - 摘要：Corrosion behaviors of magnesium alloy in 1% NaCl solution containing NaF or Na2CO3 or borate（1g/L,respectively）were investigated by immersion and polarization curve.The results indicate that corrosion rates of Mg-7.3Al magnesium alloy in three buffered solution are decreased with immersion time extending,which tends towards stable state after immersion for 48 hours.Degrees of corrosion rate are as follows:NaCO3 more than borate more than NaF under the same immersion time.Corrosion potential is slightly increased with the presence of buffers,in which the highest corrosion potential can be observed in 1% NaCl solution containing Na2CO3.Buffering effects follows in the order:Na2CO3 more than NaF more than borate.Na2CO3 exhibits desirable buffered effect on the Mg-7.3Al magnesium alloy.关键词：Mg-7.3Al Alloy;Inorganic Buffer;Corrosion Rate;Polarization Curves
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发布时间：2023-12-18 - 摘要：The principle of determining pouring position was described.It is must be considered in processing design for alloy material,processing selection,structure features of product and practical working circumstance of the enterprises.关键词：Aluminum Alloy;Permanent Gravity Casting;Pouring Position
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发布时间：2023-12-18 - 摘要：Effects of heat treatment on corrosion behavior of cast Al-Si-Mg alloy in NaCl solution were examined by immersion testing and electro-chemical analysis.The microstructure of the immersed alloy was observed by OM（optical microscope）and SEM（scanning electron microscope）.Effect of heat treatment on corrosion behavior of the alloy was approached.The results show that the lowest corrosion current density in solution treated alloy can be obtained,showing the best corrosion resistant behavior,and then as-cast alloy,next then peak aging alloy.
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发布时间：2023-12-18 -
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