The Influence Of Sc On Microstructure And Properties Of Aluminium Alloy With High Mechanical Property And Conductivity

The foundry 6201 aluminium alloys with different content of Sc added in was achieved by melting and casting techniques in this dissertation. Hot extrusion was used to deform the foundry alloy and electrical aluminium alloy rods was achieved. The alloy rods was heat treated after hot extrusion. Mechanical property, conductivity and corrosion resistance of the alloys were tested. Metallography, SEM and TEM with EDS were used to research the existing state of Sc and how Sc affect the structure and property of the alloy.Research result claims that tensile strength of T5 state alloy increases when Sc content increases and strength reaches 304MPa with 0.2wt% Sc,46.2% higher than that of 6201 alloy without Sc. While conductivity decreases with the increasing Sc content and reaches 53.8%IACS,6.9% lower than that of 6201 alloy without Sc. Sc makes the structure of alloy fine and precipitates as secondary phase which strengthens the matrix. According to the result of NSS(neutral salt spray) experiment and Tafel curve, corrosion resistance of the alloy is enhanced with the increasing content of Sc. Hardness of the T6 state alloy reaches the peak value when age time is 10h as well as conductivity of the alloy. With the increasing content of Sc, hardness of the T6 state alloy increase while conductivity decreases. Corrosion resistance of the T6 state alloy is enhanced as Sc content increases. Hardness value, as well as conductivity, of the alloy by T8 process with mass deformation is higher than that of the alloy by T8 process with small deformation because cold deformation facilitates secondary phase to precipitate. Age hardening curves of the T8 alloy follow the same pattern as T5 and T6 as well as corrosion resistance. Comparing alloys of T5, T6 and T8 state, it turns out that T6 state alloy has the highest hardness value as well as mechanical property. T5 has the lowest hardness value. However, hardness to Sc content ratio is highest of T8 state alloy and the hardness value is even higher than that of T6 state alloy when Sc content is 0.2wt%. In that case,T8 process is a method with high potential.T5 state alloy has the best conductivity and T6 state alloy has the worst one. Corrosion resistance of T8 state alloy is the best and the one of T5 state alloy is the worst.