Microstructure evolution and precipitation of SiC particle reinforced Al-20Si composite solidified under high pressures

Evolution of microstructure and precipitation process of 40%SiC _p/Al-20Si composite solidified under high pressures were investigated. The results demonstrate that undissolved Si phase under 1 GPa is much smaller than 0.02 GPa, and disappears under 2 GPa. Primary α-Al phase appears at 1 GPa, and with increased pressure, more primary α-Al phase emerges. Eutectic silicon phase is modified effectively under high pressures. A supersaturated Al(Si) solid solution is obtained. GP zones form in primary α-Al phase when solidified under 3 GPa and nature aging for 400 days. Dispersed and fine Si phase precipitates by manual aging at 209 °C.