Influence Of Magnetic Fields On Solidification And Aging Process Of 6063 Aluminum Alloy

Magnetic fields,as a physical field,have been widely applied due to obtain a fine solidification structure and hence to improve the metallurgical quality and the mechanical properties of materials.The fine solidification structure of the treated alloy can be accomplished by interaction between metal and magnetic fields.In this paper,the effect of solidification process and the aging process under the action of an external magnetic field on micro structure and mechanical properties of 6063 aluminum alloy were studied.Alternating current magnetic field(ACMF)and pulsed magnetic field(PMF)with different magnetic field strength was imposed into solidification process which was characterized by range of temperature and then observe the changes of micro structure and properties of alloy.The optimal temperature range,which most effective on the grain refinement and mechanical properties,of two kinds of magnetic fields were confirmed.In this case,the solidification behavior of metal which under the action of magnetic field can be interpreted.Research shows that the grains of 6063 aluminum alloy treated by ACMF during the incubation stage was significantly refined.The rate of grain refinement is higher when the ACMF is applied in the nucleation process of aluminum alloy than that before and after the nucleation and growth completion of grains,as well as the ACMF with frequency of 10Hz is better than the applied ACMF frequency of 20Hz.The grain refinement of imposing ACMF in the whole solidification process is better than imposed ACMF in any temperature range.The effect of pulsed magnetic field on the solidification structure of 6063 aluminum alloy was also studied.It was concluded that the pulsed magnetic field played a role in grain refinement during the solidification process.The optimal grain refinement of imposing PMF in the process of grains nucleation stage was confirmed.Although,the rate of grain refinement increases with the increase of the PMF voltage,the casting defects of solidification structure appeared when the pulse voltage increases too high so that pulse voltage 4KV was chosen in this paper.The long needle like ?-Al-Fe-Si phase was transfer to the short rod like?-Al-Fe-Si phase as the ACMF and PMF was imposed during the solidification stage,which reduces the cutting effect to the matrix and improves the hardness of the alloy.Furthermore,contents of the solute atoms in the crystals increases due to the effect of magnetic fields.Two kinds of magnetic fields also increase the hardness of the alloy,but have no obvious effect on the electrical conductivity of alloy.The effect of magnetic field on aging process of 6063 aluminum alloy has been performed.It was found that the hardness was higher than those without imposing magnetic fields,but it has scarcely any affect on the conductivity.This most likely because the accelerates of the diffusion velocity of atoms and the formation of second phase when the samples were treated by ACMF.and PMF.Therefore,the aging process time,also,can be significantly reduced.