No abstract

Microstructural evolution and mechanical properties of Al-12Si alloy subjected to equal-channel angular extrusion (ECAE) were investigated. The high stresses imposed in ECAE led to the fragmentation of the needleshaped eutectic silicon plates into smaller particles. The length and width of the Si particles decreased from 35.5±31.8 µm and 13.7±8.9 µm without ECAE to 2.7±1.1 µm and 1.3±0.4 µm after six ECAE passes, respectively. The average aspect ratio of 3.2±1.8 for the Si particles in the as-cast condition decreased to 1.18±0.8 after six ECAE passes with a corresponding increase in the average roundness of 0.26±0.19 to 0.61±0.19. ECAE increased the strength, ductility, and impact toughness of the alloy. The increase in the tensile and yield strengths after six passes was about 68 % and 100 %, respectively. The alloy after six ECAE passes exhibited 12 % elongation to failure, which was almost eight times higher than that of the as-cast alloy. The absorbed energy increased with an increase in the number of passes, finally reaching 11.5 J/cm 2 after six passes, which is about four times higher than that of the as-cast alloy.