The effects of testing temperature, imposed strain rate, heating rate up to testing temperature and holding time before stretching on the total plastic strain have been investigated in warm-rolled 7475 aluminum alloy sheets. The value of strain rate sensitivity parameter, m, (=∂lnσ/∂lnε) and apparent activation energy for plastic flow were also measured. Mechanical characteristic and optical microscopic observations showed that in order to take large superplastic elongation the specimens should be heated quickly up to the optimum testing temperature and be stretched just before the advent of static recrystallization. The value of m was about 0.2 in the range of temperature from 583 to 650K, however, it increased with increasing temperature and reached about 0.55 above 770K. The apparent activation energy for plastic flow was 358kJ/mol in the temperature range of superplastic flow. Compensating by the change in grain size and elastic modulus at testing temperature, the activation energy reduced to 160kJ/mol. This suggests that the grain accommodation during superplastic flow is controlled by the bulk diffusion.

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Behaviors of the molten metal in practical disk and plate-like die cavities were investigated by the use of metal flow sensors newly developed. Density distribution in the die castings was measured. Water and molten AC4B alloy analogues of metal flow respectively in rectangular transparent resin and metal molds were also performed. The slow/fast shot velocity changing point is located in the runner. The molten metal flows through the gate at a rate as fast as 15 to 20m/s. The flowing metal entraps gases near the gate resulting in internal defects. The volume of entraped gases and also internal defects are reduced by slowing down the metal velocity through the gate or transferring the slow/fast shot velocity changing point into the die cavity.

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In order to develop particle-reinforced aluminum composites with advanced properties, the effect of submicron ceramic particles dispersed by high-energy milling was investigated. The composites consisted of commercially pure aluminum matrix and 0.5μm Al₂O₃ particles; the volume fraction of particles ranged from 0 to 30%. The composites showed high tensile strength paticularly at elevated temperatures and good resistance to softening; the composite with 30vol% Al₂O₃ particles had a tensile strength of 20kgf/mm² at 400°C. This excellent heat-resistance of the composites was considered to arise from the very fine dispersoids of aluminum oxides and carbides generated during high-energy milling. The composites also exhibited good ductilities under compressive conditions. The dispersed Al₂O₃ particles increased elastic modulus and decreased thermal expansion coefficient. The wear resistance of the composites was also improved by Al₂O₃ particles.

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The chip treatability is one of the most important problems in NC machining. The application of chip-breaker to NC machining of aluminum alloys was studied. It was found that the application of chip-breaker to NC machining would be possible by applying the chip-breaker having proper dimension. The effect of cutting conditions on the dimention of breaker, coolant and direction of chip flow were discussed.

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Near [011], [111], [112] and [001] oriented, as well as intermediate between [011] and [112] oriented aluminum single crystals were tensile deformed at 296, 573 and 673K to 20 to 60% elongation. The orientation changes were examined by X-ray pole figures. The orientation in [112] specimens shows no change in the deformation. Pole intensities of both [111] and [001] specimens indicate some dispersion in the pole figures, but the centers of intensity move scarcely. These behaviors are independent of the deformation temperature. [001] specimens split into two orientation components. Though slip systems depend on the temperature, the two components compensate each other so that specimens do not rotate. Specimens oriented intermediate between [001] and [112] rotate at 673K singly toward [112], while at 296 and 573K the second compensating component is observed as well. The macroscopically more inhomogeneous deformation occurs at 673K than at 296K. The behaviors at 573K are similar to those at 296K.

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