Microstructures and mechanical properties of SiCp/Mg-xAl-2Ca composites collectively influenced by SiCp and Al content

The SiCp/Mg-xAl-2Ca composite with different (2, 3, 5 and 9 wt%) Al content is fabricated by stir casting. After be extruded at 673 K with the ratio of 16:1, the microstructures and mechanical properties of the composites are investigated. As compared with Mg-xAl-2Ca alloys, the addition of SiCp has no obvious effect on the category of precipitated phase, but increases its volume fraction and is propitious to the uniformity of microstructures. With the application of extrusion, precipitated phase is refined and its distribution is improved obviously. The yield strength of the composites increases with the increasing of Al content as a result of an increased amount of precipitated phase. The ultimate tensile strength and elongation are improved as the Al content increased from 2 wt% to 5 wt%, but deterioration happens when the Al content is increased to 9 wt%. Addition of SiCp lows down the strength of Mg-2Al-2Ca alloy, however, leads to the increased strength of Mg-3Al-2Ca alloy and Mg-5Al-2Ca alloy. Even though the yield strength of SiCp/Mg-9Al-2Ca composite is similar to Mg-9Al-2Ca alloy, it owns a lower ultimate tensile strength.