Study On Heat Treatment And Deformation Of High Performance Al-Mg-Si-Sc-Zr Alloy

With the development of the power industry,development of high performance of aluminum alloy wire material has drawn great attention.In the current dissertation,the new Al-Mg-Si-Sc-Zr alloy containing a little Sc and Zr was prepared by vacuum casting method.The microstructures and properties of the alloy and the mechanism of a little Sc and Zr element during process of homogenization,solid solution,aging heat treatment and rolling deformation were systematically investigated based on optical microscope(OM),scanning electron microscopy(SEM)and transmission electron microscopy(TEM)observes,hardness,conductivity and tensile tests.And the optimized technical parameters of heat treatment and deformation were determined.The distribution of the microstructure of this new Al-Mg-Si-Sc-Zr alloy ingot is uneven.The size of grain was large,and the segregation phenomenon was existent.The interdendritic segregation was significant improved and non-equilibrium phases was dissolved completely,the grain boundaries were smooth and continuous and the microstructures were uniform after the alloy was homogenizationed at 520°C for 12 hours.The conductivity of the alloy ingot was improved from 52.1%IACS to 55.5%IACS after homogenizationed at 520°C for 24 hours.The new Al-Mg-Si-Sc-Zr alloy after extruding and rolling was recrystallized during the solution treatment at 600°C,and the supersaturated solid solution was formed sufficiently while the grain was not grown obviously after solution treatment for 16 hours.In the process of high temperature aging at 350°C,the hardness and conductivity of the Al-Mg-Si-Sc-Zr alloy were increased by 34 HV and 6.7%IACS due to the precipitation of A13(Sc,Zr)precipitated particles in the alloy.In the process of low temperature aging at 150°C,the hardness and conductivity of the alloy has a little improvement further,due to the precipitation of a small amount of Mg2 Si strengthen phase in the alloy.In order to improve furtherly the mechanical properties of the new Al-Mg-Si-Sc-Zr alloy,cold rolling deformation treatment was introduced to increase the dislocation density in the organization.The tensile strength,yield strength,elongation and conductivity of the new Al-Mg-Si-Sc-Zr alloy(alloy 1)are 325 Mpa,231MPa 5.49% and 55.0%IACS respectively,and the comprehensive performance is fine,after thermomechanical treatment with solid solution at 600°C and high temperature aging at 400°C and cold rolling deformation of 90% and low temperature aging at 150°C.We mainly use the interaction of age strengthening and deformation strengthening in the whole process,the results can provide theoretical and technical support for industrial production.