4045/3003/4045 aluminum alloy clad sheets having the same thickness (6.0 mm) and clad ratio (12%) were fabricated both by hot roll-bonding and vertical-type high-speed tandem twin-roll casting. The clad sheets were cold-rolled to 0.17 mm in thickness, annealed at 400°C for 2 h, cold-rolled to 0.10 mm in thickness and finally subjected to heat treatment for brazing at 600°C for 3 min. Microstructures and mechanical properties of the clad sheets were investigated in each stage. Al–Mn dispersoid particles in the core (A3003) and Si particles in the overlay (A4045) of the cold-rolled sheet with 0.17 mm thickness originating from the twin-roll casting were smaller than those originating from the hot roll-bonding. Interfaces between the core and the overlay were clearly observed in the twin-roll casting sheets. A fully recrystallized structure was observed after annealing in the sheet originating from the hot roll-bonding, while the fibrous structure still remained in the sheet originating from the twin-roll casting. Yield strength, tensile strength and elongation of the annealed sheet originating from the twin-roll casting were higher than those originating from the hot roll-bonding. After heat treatment for brazing, the tensile strength was the same in both clad sheets.

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The influence of molding conditions on the strength of the magnesium alloy products formed using an injection molding method was examined. Test pieces were cut from a plain plate made of AZ91D, which was molded in a metal die using a Thixomolding machine. The test piece, whose thickness was 2.5 mm, was examined. The barrel temperature was varied from 873 to 903 K, and the gate velocity was varied to the extent possible, between 11.4 and 28.7 m/s. The mold temperature ranged from 423 to 483 K. The test pieces' performance was determined using a tensile test. The main results obtained are as follows. The calculated average roughness decreased when the gate velocity increased. The tensile strength improved because the chill rate increased when the temperature of the mold decreased. The 0.2% proof strength was not influenced by the shooting conditions in this study. The tensile strength and the elongation to fracture depended strongly on the gate velocity.

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Al–Zn–Mg alloy has been known as one of the aluminum alloys with the good age-hardening ability and the high strength among commercial aluminum alloys. The mechanical property of the limited ductility, however, is required to further improvement. Four alloys were prepared with or without alloying elements of Cu and Ag. Precipitation sequences on the alloys were investigated with hardness measurements and TEM observations. Ag or Cu added alloy showed higher maximum hardness than Ag or Cu free alloy. The number densities of the precipitates in Ag or Cu added alloys were higher than those in Ag or Cu free alloys. The GP (II) zone and η′ phase were observed in all alloys peak-aged at 423 K, although GP (I) zone were observed in the Cu added alloy.

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