Study On High Conductivity And High Strength Aluminum Alloy Material

6xxx(Al-Mg-Si)aluminium alloy is widely used in various fields as a heat-treatment strengthening alloy.In order to meet the different requirements in application,the comprehensive properties of the alloys were improved by adjusting the composition of the alloys,changing the processing state of the materials and optimizing the heat treatment process.In this paper,Al-Mg-Si alloy is studied.The effects of alloy composition and heat treatment process on the structure and properties of AI-Mg-Si alloy were studied by means of microhardness,conductivity tester,universal material testing machine,metallographic microscope,X-ray diffraction,scanning electron microscopy and energy spectrum analysis.By adjusting the atom ratio of Mg and Si,Zn,B,Ti and other elements in the alloy,combining solid solution treatment and aging heat treatment process,the conductivity and tensile strength of the alloy are optimized.As a result,a high conductivity and high strength Al-Mg-Si alloy with 50%IACS conductivity and 350 MPa is produced.At the same time,the thermal exposure experiment was used to simulate the actual high temperature environment.The changes of the properties of the alloys under different aging conditions were tested to determine the deterioration degree of the alloys,and to explore the structural stability of the alloys.The results show that:When the molar ratio of Mg to Si is 1.4,the tensile strength of the alloy increases obviously and the conductivity maintains at 50.5%IACS.0.5%Zn can further optimize the strength,while slightly reducing the conductivity;B element can eliminate the impurity Fe element in the matrix and refine the grain,improve the electrical conductivity and strength of the alloy.Under the combined action of B and Zn,the electrical conductivity of the alloy is maintained at about 50.0%IACS,and the strength of the alloy is further enhanced.The best effect of fine grain strengthening can be achieved when the static time of the refiner is 5 minutes,and the average grain size is 50 microns.The optimum solid solution process is 560?*1h.The supersaturated solid solution is obtained without coarsening of the grain.The peak of aging process is aging at 185? for 10-15h in this paper.It can maximize the tensile strength of the alloys and obtain higher conductivity,which satisfied the performance requirements of 50%IACS and 350MPa.Tthe alloy contains Mg2Si precipitated phase which size is 5?m at aging time of 10h,15h and 20h.The beta phase is different from the needle-like phase observed by TEM in other literatures and is irregular granular.The size of the precipitated phase is about tens of nanometers and the acicular morphology is not obvious.The peak curve of XRD shows that the beta phase has been formed after aging for 10 hours,and the plateau of the aging peak from 10 to 15h is determined by beta phase.The effect of thermal exposure temperature on the properties of the alloy:the thermal stability of best aging state is more stable than low temperature aging state;Zn element and refiner can increase the thermal stability of the alloy and maintain the tensile strength and conductivity of the alloy at higher thermal exposure temperature.The state and content of the second phase in the alloy structure determine the changes of electrical conductivity and mechanical properties after thermal exposure.