Modifying Al–7Si–0.35Mg alloys using equal channel angular extrusion

The 356 alloys which are different in the composition of Sr and Fe elements were heavily deformed by equal channel angular extrusion. The large acicular silicon in the unmodified alloy and the Fe-bearing phases act as crack initiators and provide easy paths for fracture. After extruded for 5 passes, the acicular silicon and Fe-bearing phases are obviously refined and rounded, both of which resulted in the higher values of mechanical properties. The elongation is greatly enhanced because the cracks have less opportunity to grow continuously along the boundaries of refined phases. The tensile strengths are also enhanced due to the recrystallized and finer grains.