Microstructure refinement and mechanical properties improvement of Al-Si-Fe alloys by hot extrusion using a specially designed high-strain die

A heteromorphic extrusion die with right-angle corners in the die hole was designed in this study to give a high local strain to the extrudate metal during hot extrusion of Al-Si-Fe alloys, and the strain distribution in the extrudate metal was evaluated using the finite element method. It was demonstrated that the change in metal flow direction at the right-angle corners is effective for generating high strain in the extrudate metal and refining brittle inclusion particles such as primary Al9Si2Fe2 (beta phase) particles and eutectic Si particles. The refinement of these particles led to significant improvements in tensile elongation and plastic deformability in cold rolling of the alloys