The Effect of Si and Extrusion Process on the Microstructure and Tensile Properties of Mg-Mg2Si Composite

This investigation has been carried out to study the influence of extrusion process on microstructure and tensile properties of Mg-Mg2Si composite with different amounts of Si (3, 5 and 7 wt.%). Microstructural examination was carried out using optical microscopy (OM). The cast specimens were extruded at 350 °C at different extrusion ratios (6:1, 12:1 and 18:1). The results showed that the specimens with lower Si contents, have higher ultimate tensile strength (UTS) and tensile elongation values. Moreover, there was a considerable improvement in tensile properties for the specimens extruded with the ratio of 12:1 and 18:1 in comparison to the specimens of 6:1. This can be attributed to the significant reduction in size of primary Mg2Si particles from more than 200 μm to 20 μm, 10 μm and 5 μm after extrusion with the ratio of 6:1, 12:1 and 18:1, respectively. The highest UTS values were found to be 265 MPa for extruded with 1:18 ratio of Mg-3Si composite.