The effects of Zn addition on aging behavior in A6063 aluminum alloy were investigated by Vickers hardness measurement, tensile test, electrical conductivity measurement, scanning electron microscopy and transmission electron microscopy. The alloys contained the amount of 0.01 and 0.2mass%Zn, respectively. The samples were cooled by fan or in the air after hot extrusion and then conducted aging treatment. The hardness level and tensile strength of 0.01Zn and 0.2Zn were almost the same in fan

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... ling condition. On the other hand, mechanical properties of 0.2Zn were lower than those of 0.01Zn in air cooling condition due to hardenability deterioration. Cross sectional area of precipitates of 0.2Zn was larger than of 0.01Zn. Besides, distribution of precipitate cross section of 0.2Zn was coarser than 0.01Zn. However, η phase or T phase which can be observed in Al-Zn-Mg alloys did not exist in Al matrix even when A6063 aluminum alloy contained up to 0.2mass% Zn.