Monotetic alloy have been researched for hundred years.Recent years,researchers have prepared homogeneous monotectic alloy by electro-magnetic body force(EMBF).But the mechanism of separation and refinement of the sec...Monotetic alloy have been researched for hundred years.Recent years,researchers have prepared homogeneous monotectic alloy by electro-magnetic body force(EMBF).But the mechanism of separation and refinement of the second phase in liquid matrix by EMBF is not very clear.This paper investigated the effect of different AC EMBF on the microstructure and solidification process of Zn-10%Bi hyper-monotectic alloy by quenching the samples in water under high static magnetic field.It is shown that,the superimposing of AC EMBF can influence the moving speed of the second phase droplet and damp the gravity segregation in solidifying Zn-10%Bi alloy.When the AC EMBF reaches 5×10~5N/m^3 in different magnetic flux densities from 2 to 10 Tesla,the homogenuous distribution of bismuth particles could be achieved,A physical model is established to illustrate the mechanism of separation and refinement of the second Bi droplets at the stage of liquid-liquid separation by AC EMBF.The results show that the second droplets can be divided into two or three smaller droplets by Lorenz force caused by induced current at the former and later location of bismuth droplet.When the bismuth droplet moves at a proper speed which is adjusted by EMBF,it will be broken down by Lorenz forces.展开更多
In order to obtain homogenous Zn-Bi hyper-monotectic alloys and investigate what mechanism the magnetic field functions,we carried out the solidification experiments of Zn-4wt%Bi,5wt%Bi,6wt%Bi,7wt%Bi, 15wt%Bi and 30wt...In order to obtain homogenous Zn-Bi hyper-monotectic alloys and investigate what mechanism the magnetic field functions,we carried out the solidification experiments of Zn-4wt%Bi,5wt%Bi,6wt%Bi,7wt%Bi, 15wt%Bi and 30wt%Bi alloys under a 18T static magnetic field which was set up in LNCMI.Water quenching was also chosen to further damp the segregation caused by Stokes convection and Marangoni movement.The results indicated that when the content of Bismuth is 5-7wt%,the superimposition of 18Tesla magnetic field can damp the segregation remarkably,and the size of the second phase particles also is decreased.Furthermore,to Zn-4wt%Bi alloy solidified in 18T magnetic field,no spherical bismuth particles are found even magnifying 1000 times by microscope, which hints that the 18T magnetic field may change its solidifying character.To Zn-15wt%Bi and Zn-30wt%Bi alloy, due to their strong segregation trend,the 18T magnetic field still cannot damp the Stokes settlement thoroughly even by quenching way,however,no layered bismuth and zinc appears when compared to 0T,large Bismuth block are formed in the lower half part of the sample.展开更多
A physical simulation was carried out to investigate the realistic experiment of bulk solidifying the Zn-Bi hyper-monotectic alloy under various compound electric-magnetic fields(CEMF).For this experiment,two crucial ...A physical simulation was carried out to investigate the realistic experiment of bulk solidifying the Zn-Bi hyper-monotectic alloy under various compound electric-magnetic fields(CEMF).For this experiment,two crucial parameters determinate the cast microstructure,the one is electric-magnetic force(EMF)and the other is the frequency of AC current.Results show that the minor phase could be mixed in the other phase from the initial layered structure when the EMF above a specific value under fixed frequency,and the average diameter of minor phase droplet decreases with increasing EMF.The evolution of the liquid phases structure is reasonable agree with the realistic experiment of Zn-Bi hyper-monotectic alloy,which suggests that the mechanism revealed by the physical simulation could represent the one in the realistic experiment.展开更多
基金Item Sponsored by National Science Foundation of China (No.50974085No.51034010) +4 种基金Development Foundation for Talents in Shanghai (No.2009046) National High-tech R&D Program of China (No.2009AA03Z109) Key Research and Innovation Program from Shanghai Municipal Education Commission (No.09zz98) Key Project from Science and Technology Commission of Shanghai Municipality (No:09dz120640109dz1206402)
文摘Monotetic alloy have been researched for hundred years.Recent years,researchers have prepared homogeneous monotectic alloy by electro-magnetic body force(EMBF).But the mechanism of separation and refinement of the second phase in liquid matrix by EMBF is not very clear.This paper investigated the effect of different AC EMBF on the microstructure and solidification process of Zn-10%Bi hyper-monotectic alloy by quenching the samples in water under high static magnetic field.It is shown that,the superimposing of AC EMBF can influence the moving speed of the second phase droplet and damp the gravity segregation in solidifying Zn-10%Bi alloy.When the AC EMBF reaches 5×10~5N/m^3 in different magnetic flux densities from 2 to 10 Tesla,the homogenuous distribution of bismuth particles could be achieved,A physical model is established to illustrate the mechanism of separation and refinement of the second Bi droplets at the stage of liquid-liquid separation by AC EMBF.The results show that the second droplets can be divided into two or three smaller droplets by Lorenz force caused by induced current at the former and later location of bismuth droplet.When the bismuth droplet moves at a proper speed which is adjusted by EMBF,it will be broken down by Lorenz forces.
基金Item Sponsored by National Science Foundation of China (No.50974085No.51034010) +5 种基金Development Foundation for Talents in Shanghai (No.2009046) National High-tech R&D Program of China (No.2009AA03Z109) Key Research and Innovation Program from Shanghai Municipal Education Commission (No.09zz98) Key Project from Science and Technology Commission of Shanghai Municipality (No:09dz120640109dz1206402) EuroMagNET under the EU contract n 228043
文摘In order to obtain homogenous Zn-Bi hyper-monotectic alloys and investigate what mechanism the magnetic field functions,we carried out the solidification experiments of Zn-4wt%Bi,5wt%Bi,6wt%Bi,7wt%Bi, 15wt%Bi and 30wt%Bi alloys under a 18T static magnetic field which was set up in LNCMI.Water quenching was also chosen to further damp the segregation caused by Stokes convection and Marangoni movement.The results indicated that when the content of Bismuth is 5-7wt%,the superimposition of 18Tesla magnetic field can damp the segregation remarkably,and the size of the second phase particles also is decreased.Furthermore,to Zn-4wt%Bi alloy solidified in 18T magnetic field,no spherical bismuth particles are found even magnifying 1000 times by microscope, which hints that the 18T magnetic field may change its solidifying character.To Zn-15wt%Bi and Zn-30wt%Bi alloy, due to their strong segregation trend,the 18T magnetic field still cannot damp the Stokes settlement thoroughly even by quenching way,however,no layered bismuth and zinc appears when compared to 0T,large Bismuth block are formed in the lower half part of the sample.
基金Item Sponsored by National Science Foundation of China (No.50974085) National High-tech R&D Program of China (No.2009AA03Z109) +3 种基金Key Project from Science and Technology Commission of Shanghai Municipality (No.09dz1206401No.08dj 1400404 and No.08DZ1130100) Development Foundation for Talents in Shanghai (No.2009046) Specialized Research Fund for Doctoral Program of Higher Education (No.20093108110012)
文摘A physical simulation was carried out to investigate the realistic experiment of bulk solidifying the Zn-Bi hyper-monotectic alloy under various compound electric-magnetic fields(CEMF).For this experiment,two crucial parameters determinate the cast microstructure,the one is electric-magnetic force(EMF)and the other is the frequency of AC current.Results show that the minor phase could be mixed in the other phase from the initial layered structure when the EMF above a specific value under fixed frequency,and the average diameter of minor phase droplet decreases with increasing EMF.The evolution of the liquid phases structure is reasonable agree with the realistic experiment of Zn-Bi hyper-monotectic alloy,which suggests that the mechanism revealed by the physical simulation could represent the one in the realistic experiment.
