Abstract
The dependences of stress-strain curves, critical resolved shear stress (CRSS) and deformed structure on the aging temperature and time were studied on Al-0.4, -0.8 and -1.2at%Si single crystals. Stress-strain curves show parabolic hardening. The total elongation steeply decreases when CRSS begins to increase. CRSS reaches a maximum in the Al-0.8 and -1.2at%Si alloys aged at 150°C for 400hr, at 200°C for 4 to 6hr and at 250°C for 0.1hr, and decreases in those aged for longer time. Precipitates change in shape from sphere in the early stage of aging to rod or plate, and finally to lump. The band like deformed regions with high dislocation density in which dislocations severely curve are found in the low strained alloys at early stage of aging. Dislocations may cut through precipitates during deformation. The dislocation structure showing "by-pass mechanism" are found at the overaged stage.
