Effect Of Sc On Mechanical Properties And Precipitation Phase Evolution Path Of 6063 Aluminum Alloy

6000 series aluminum alloy are widely used as lightweight materials in the automotive field due to the high specific strength,excellent formability and corrosion resistance.However,the strength of the 6000 series aluminum alloy is insufficient,and the collision performance of the vehicle is facing severe challenges.A lot of work have shown that the most effective way to improve the strength and plasticity of 6000 series aluminum alloy is to introduce other alloying elements to the alloy system,and then adjust the strengthening phase precipitation of 6000 series aluminum alloy to obtain an excellent alloy.The main research contents and innovations are as follows:1.Based on Vickers hardness,the appropriate solution treatment temperature and time of Sc-containing 6063 aluminum alloy and its multi-stage aging heat treatment process are explored.The heat treatment process is:holding at 550°C for 2 h,immediately holding at 250°C for 1 h,and finally holding at 170°C for8 h.2.In order to study the effect of Sc on 6063 aluminum alloy,the basic mechanism for controlling the properties of Sc-containing 6063 aluminum alloy during aging at 170°C are revealed by using atomic-scale scanning transmission electron microscopy,electron energy loss spectroscopy,and first-principles calculations:SSSS?atomic clusters?GP zones??"/sub-B'??"/sub B'-V_Sc??',Sc can occupy the sub B'structure and form a sub B'-V_Scstructure in the?"phase,and the sub B'-V_Sc structure can suppress the transformation and coarsening of the?"phase,resulting in the formation of extremely long?"phase.3.High-resolution transmission electron microscopy found that the B'phase of 6063 aluminum alloy during aging at 170°C may have an effect on the transition from?"to?',and proposed two potential evolutionary paths for the precipitation phase.4.In order to study the influence of Sc on the B'phase,the possible occupation of Sc in the B'phase is discussed on the basis of the first-principles calculations.The results show that Sc tends to replace the position of the Mg atom in the B'phase.