Al-Si-Mg alloys have good castability and high strength can obtained by aging heat treatment. There are some reports about the age-hardening behavior of these alloys. However, the effect of additive elements on the age-hardening behavior with microstructure evolution in Al-Si-Mg alloys is not totally clarified yet. In the previous work, the effect of T5 heat treatment for age-hardening behavior and microstructure evolution in AC4C cast alloy were investigated. Fine rod-like precipitates which were reported in Al-Mg-Si alloy were observed near eutectic Si phase in AC4C alloy. Rod-like precipitates became coarser toward the center of α-Al dendrite. In this work, high purity AlSi-Mg alloys were fabricated, and the microstructure of the alloys in T5 condition was investigated by transmission electron microscopy (TEM). In Al-7%Si-0.4%Mg (mass%) alloy aged at 473K for 7.2ks, lots of needle-like precipitates, which were identified as β'' phase, were observed near the eutectic Si phase. On the other hand, rod-like precipitates and granular precipitates were observed far from the eutectic Si phase. Based on SAED patterns obtained from the rod-like precipitates and granular precipitates, Those precipitates were identified as Type-A precipitates and Si phase, respectively.
In this study, porous Mg-Zn composites with designed relative density were manufactured by spacer method. The effects of porosity and Zn addition rate on the compression properties were investigated. The relative density of the manufactured porous Mg-Zn composites were a little lower than the design value, but it was almost controllable. The compressive stress-strain curves of porous Mg-Zn showed the peak value of stress in the initial stage of deformation followed by a long plateau and the steeply rise in stress by densification. The compression properties showed relative density dependence, and the higher the relative density, the higher the Youngʼs modulus, plateau stress, and initial peak stress. Youngʼs modulus increased as the amount of Zn added increased, but the plateau stress and initial peak stress were higher when Zn was added at 5 mass% than when 10 mass% was added.
Porous aluminum is multifunctional metal materials with light weight and high energy absorption properties. In our previous study, it was shown that continuously production of same alloy porous aluminum by continuously foaming of precursors using a conveyor with optical heating was possible. In this study, continuously foaming of dissimilar alloy precursors on same line was investigated. It is difficult to foam dissimilar alloy precursors on same line because their liquidus temperatures are different. So each heat input of precursor was adjusted by changing distance between precursor and halogen lamps. Two types of precursors, commercially pure aluminum (A1050) and die-casting aluminum alloy (ADC12), were fabricated via the friction stir welding route. Continuously production of dissimilar alloy porous aluminums was carried out by passing of precursors below heating area of halogen lamps. It was found that different alloy aluminum precursors can be continuously foamed on the same line. The obtained porous aluminum had porosity with approximately 80% and good pore structures.