Microstructure and Impact Property of Al-26%Si Alloy after Equal Channel Angular Pressing

Equal channel angular pressing (ECAP) technology was applied to Al-26%Si alloy for refining the microstructure, the impact property and fracture morphology of the alloy were studied at different temperatures. The results show that ECAP could effectively refine grains of the alloy, decrease block primary silicon size and passivate edges. Needle-like eutectic silicon in granylar form dispersed in matrix. Room temperature impact energy of the alloy was 5 times of that of as-cast sample after pressing for 16 passes at 300 ℃. At low temperature, impact property of the alloy changed little with the decrease of temperature after pressing for 16 passes. Impact property of the alloy decreased when impact temperature raised to 100 ℃ from room temperature. The fracture mechanism of as-cast and pressed samples was mainly brittle fracture and ductile fracture respectively.