A new process using direct current pulsed magnetic field for modification of solidification structure of pure aluminium has been investigated.The experimental results show that the fine equiaxed crystal zone exists at...A new process using direct current pulsed magnetic field for modification of solidification structure of pure aluminium has been investigated.The experimental results show that the fine equiaxed crystal zone exists at the bottom of ingots with pulse magnetic,and with the increase of rated output current the equiaxed grains are more finer.展开更多
Time-resolved X-ray imaging with intense,high brightness and monochromatic third-generation synchrotron radiation,and a high-resolution fast-readout charge coupled device(CCD)system have been used to in-situ observe t...Time-resolved X-ray imaging with intense,high brightness and monochromatic third-generation synchrotron radiation,and a high-resolution fast-readout charge coupled device(CCD)system have been used to in-situ observe the dendrite growth of a solidifying Al-10wt.%Cu alloy under pulsed magnetic field.The imaging results indicate that the secondary dendrite tip growth underwent a rapid deceleration once the pulsed magnetic field was applied.The remelting phenomenon of small dendrites was also observed when applying the pulsed magnetic field at the beginning of solidification.This is related to the Joule heat effect caused by the imposed pulsed magnetic field.Whilst,fragmentation of the dendrites usually caused by the forced convection induced by pulsed magnetic field was not found in the present work.展开更多
Effects of electromagnetic stirring(EMS),ultrasonic treatment(UST)and the combination of EMS and UST(EU)on solidification structure were investigated in hypoeutectic A1-Si alloy.The results indicate that EMS,UST and E...Effects of electromagnetic stirring(EMS),ultrasonic treatment(UST)and the combination of EMS and UST(EU)on solidification structure were investigated in hypoeutectic A1-Si alloy.The results indicate that EMS,UST and EU can refine primary u-A1 and modify eutectic silicon by influencing their nucleation and growth processes.EMS can fracture the dendrite arms and lead to decrease of primary α-Al grain size.It also changes the morphology of eutectic silicon and widens the separation of silicon plates.For UST,the cavitation and acoustic streaming are the principal reasons for the microstructure refinement,which enhance the undercooled and heterogeneous nucleation.EU has combined the features of EMS and UST,hence obtains the best effect on the microstructure evolution.Significant refinement of primary α-Al and evident modification of eutectic silicon are observed with EU.In addition,the mechanism of morphological evolution with EU was preliminarily discussed.展开更多
In this paper,a new electromagnetic continuous casting process to prepare clad slab is presented.The influence of level direct current electromagnetic field on temperature and flow fields of the melt during the fabric...In this paper,a new electromagnetic continuous casting process to prepare clad slab is presented.The influence of level direct current electromagnetic field on temperature and flow fields of the melt during the fabrication of clad slab were numerically studied by the engineering software ANSYS and FLUENT.The results indicated that when the magnetic flux density(B)was 0.15 T,the impact velocity and distance of the flow to the narrow face and underside of the dividing plate decreased remarkably.So the flow impact to the liquid pool was reduced.At the same time,the high temperature zone of the melt moved away from the narrow face and the dividing plate,and distributed more uniformly. The wider semi-solid area next to the dividing plate was useful for 3003 and 4004 aluminum alloys to bond.展开更多
In metallurgical processing,effective and reliable electromagnetic stirring of the melt is one of the prerequisites for higher productivity and improved process performance.Reasonable structure and electrical paramete...In metallurgical processing,effective and reliable electromagnetic stirring of the melt is one of the prerequisites for higher productivity and improved process performance.Reasonable structure and electrical parameters of the stirrer are greatly significant on improving and enhancing the stirring quality.In this paper,ANSYS software is used to research the effect of stirrer parameters on magnetic field distribution in aluminum melting furnace.The results show that magnetic flux density distributes as two humps at the direction(X)of metal length.Magnetic flux density distributes as a hump at the direction(Z)of metal width,reaches its maximum at the pool center and decays gradually toward the edge.It is also demonstrated that magnetic flux density increases by 2.65mT,as kilo-ampere-turns increase by 2.The center distance between two coils changes the distribution of magnetic flux density rather than its magnitude,while the distance from coils to the bottom of molten aluminum changes the magnitude of magnetic flux density but no change of distribution.展开更多
The 3003/4045 aluminum alloys cladding hollow billets with the diameter of 60 mm and external thickness of 3 mm are fabricated by horizontal electromagnetic continuous casting.The surface features of ingots and micros...The 3003/4045 aluminum alloys cladding hollow billets with the diameter of 60 mm and external thickness of 3 mm are fabricated by horizontal electromagnetic continuous casting.The surface features of ingots and microstructures of the bonding interface are observed.The results show that cladding hollow billets combine the external and internal layers by metallurgical bonding without mixing when the pouring temperature of the external liquid metal is 903 K.The diffusion region with the thickness of 25 μm can be seen clearly,where mutual diffusion of Si and Mn atoms takes place. In addition,the intermetallic compound Al_(12)(FeMn)_3Si_2 is formed in the interface.展开更多
基金Item Sponsored by the National Natural Science Foundation of China[No.51074031]and the Korea national project
文摘A new process using direct current pulsed magnetic field for modification of solidification structure of pure aluminium has been investigated.The experimental results show that the fine equiaxed crystal zone exists at the bottom of ingots with pulse magnetic,and with the increase of rated output current the equiaxed grains are more finer.
基金Item Sponsored by the National Natural Science Foundation of China[Nos.5060100350971032+2 种基金51071035]the Fundamental Research Funds for the Central Universitiesand Liaoning BaiQianWan Talents Program
文摘Time-resolved X-ray imaging with intense,high brightness and monochromatic third-generation synchrotron radiation,and a high-resolution fast-readout charge coupled device(CCD)system have been used to in-situ observe the dendrite growth of a solidifying Al-10wt.%Cu alloy under pulsed magnetic field.The imaging results indicate that the secondary dendrite tip growth underwent a rapid deceleration once the pulsed magnetic field was applied.The remelting phenomenon of small dendrites was also observed when applying the pulsed magnetic field at the beginning of solidification.This is related to the Joule heat effect caused by the imposed pulsed magnetic field.Whilst,fragmentation of the dendrites usually caused by the forced convection induced by pulsed magnetic field was not found in the present work.
基金Item Sponsored by National Natural Science Foundation of China[No.50874022]
文摘Effects of electromagnetic stirring(EMS),ultrasonic treatment(UST)and the combination of EMS and UST(EU)on solidification structure were investigated in hypoeutectic A1-Si alloy.The results indicate that EMS,UST and EU can refine primary u-A1 and modify eutectic silicon by influencing their nucleation and growth processes.EMS can fracture the dendrite arms and lead to decrease of primary α-Al grain size.It also changes the morphology of eutectic silicon and widens the separation of silicon plates.For UST,the cavitation and acoustic streaming are the principal reasons for the microstructure refinement,which enhance the undercooled and heterogeneous nucleation.EU has combined the features of EMS and UST,hence obtains the best effect on the microstructure evolution.Significant refinement of primary α-Al and evident modification of eutectic silicon are observed with EU.In addition,the mechanism of morphological evolution with EU was preliminarily discussed.
文摘In this paper,a new electromagnetic continuous casting process to prepare clad slab is presented.The influence of level direct current electromagnetic field on temperature and flow fields of the melt during the fabrication of clad slab were numerically studied by the engineering software ANSYS and FLUENT.The results indicated that when the magnetic flux density(B)was 0.15 T,the impact velocity and distance of the flow to the narrow face and underside of the dividing plate decreased remarkably.So the flow impact to the liquid pool was reduced.At the same time,the high temperature zone of the melt moved away from the narrow face and the dividing plate,and distributed more uniformly. The wider semi-solid area next to the dividing plate was useful for 3003 and 4004 aluminum alloys to bond.
基金Item Sponsored by National Natural Science Foundation of China (Nos.5060100350971032+1 种基金51071035) the Fundamental Research Funds for the Central Universities and Liaoning BaiQianWan Talents Program
文摘In metallurgical processing,effective and reliable electromagnetic stirring of the melt is one of the prerequisites for higher productivity and improved process performance.Reasonable structure and electrical parameters of the stirrer are greatly significant on improving and enhancing the stirring quality.In this paper,ANSYS software is used to research the effect of stirrer parameters on magnetic field distribution in aluminum melting furnace.The results show that magnetic flux density distributes as two humps at the direction(X)of metal length.Magnetic flux density distributes as a hump at the direction(Z)of metal width,reaches its maximum at the pool center and decays gradually toward the edge.It is also demonstrated that magnetic flux density increases by 2.65mT,as kilo-ampere-turns increase by 2.The center distance between two coils changes the distribution of magnetic flux density rather than its magnitude,while the distance from coils to the bottom of molten aluminum changes the magnitude of magnetic flux density but no change of distribution.
基金Item Sponsored by National Natural Science Foundation of China[No.51074031]
文摘The 3003/4045 aluminum alloys cladding hollow billets with the diameter of 60 mm and external thickness of 3 mm are fabricated by horizontal electromagnetic continuous casting.The surface features of ingots and microstructures of the bonding interface are observed.The results show that cladding hollow billets combine the external and internal layers by metallurgical bonding without mixing when the pouring temperature of the external liquid metal is 903 K.The diffusion region with the thickness of 25 μm can be seen clearly,where mutual diffusion of Si and Mn atoms takes place. In addition,the intermetallic compound Al_(12)(FeMn)_3Si_2 is formed in the interface.
