In this study, the effect of pH on sacrificial anode effect of aluminum alloy in acidic chloride solutions containing copper ion was investigated by using immersion corrosion tests and electrical polarization measurements. The corrosion tests were performed for A3003 alone and A3003 coupled with A7072 simulated clad material. A3003 was sacrificially protected by A7072 under the solution of over pH3 at 200 ppmCl^‒. In contrast, in the case of a solution below pH2, the corrosion weight loss of A3003 coupled with A7072 did not decrease compared to that of A3003 alone. Additionally, A3003 coupled with A7072 actively dissolved similar to A3003 alone. These are because the corrosion potential of A3003 did not become less noble when coupled with A7072 due to nobler pitting potential of A7072.

Al-Zn-Mg alloys with different precipitate sizes were investigated to determine the influence of the precipitate size on the flow stress and dislocation density change during tensile deformation. The dislocation density was measured using in-situ X-ray diffraction at the SPring-8 synchrotron radiation facility with a time resolution of about 2 s. In region II with rapid dislocation multiplication, from under-aging to peak aging, the dislocation density increased with increasing aging time. Under over-aging conditions, the amount of dislocation multiplication in region II decreased with increasing aging time. Even in region III, the increase in dislocation density with plastic deformation was the largest for the peak aging conditions. However, the amount of work hardening was small and the contribution of dislocation hardening to the strength of the material was minimal. For over-aging conditions, the increase in dislocation density in region III was smaller than for the other regions, but the amount of work hardening was relatively large. It is considered that the influence of the dislocation density on work hardening is determined by the effectiveness of precipitates as obstacles to dislocation motion.

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 cooling 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.

Al-Zn-Mg alloys with a high amount of Zn (10%) were subjected to high-speed compressive deformation after solution heat treatment, and a slow strain rate tensile test (SSRT) was performed under peak-aging condition. The SSRT under a humid air atmosphere revealed that grain boundary cracks near the surface are highly suppressed when the peak-aged Al-Zn-Mg alloy was pre-deformed with a high-speed.