Effect of Si Content on Dynamic Recrystallization of Al-Si-Mg Alloys During Hot Extrusion

By using electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM), the effect of Si content on microstructure characteristics of three as-extruded Al-Si-Mg alloys was investigated. Results showed that the density of coarse Si particles played a critical role in dynamic recrystallization. Dynamic recrystallization rarely occurred in Si alloy with less Si content; however, it happened in the Si-rich zones in S2 alloy with a medium Si content. And a mature recrystallization was observed in S3 alloy with high Si content. Although deformation was carried out at high temperature, particle-stimulated dynamic recrystallization occurred in Si-rich zones.