Microstructure and mechanical properties of the Mg-Zn-Cu/SiCp composite in the as-cast and as-extruded conditions

Effects of adding different amounts of SiCp on the microstructure and mechanical properties of the as-cast and as-extruded Mg-7% Zn-1.5% Cu (ZC71) alloys were studied. The as-cast ZC71 alloy consisted of a-Mg phase that encircled with the MgZnCu and Mg(Zn,Cu)(2) intermetallics. Hot extrusion has led to a grain-refined structure with distributed intermetallics along the extrusion direction. Adding SiCp decreased the grain size values for the as-extruded composites. The Vickers hardness values increased with SiCp addition for both conditions. The ultimate tensile strength and tensile elongation (El%) values reached the optimum level with 5 wt% SiCp addition. More SiCp additions led to more agglomerations and decrement in strength and elongation. The yield tensile strength also increased with SiC additions. Adding 5 wt% SiCp changed the brittle fracture to the more quasi-cleavage. Hot extrusion altered the fracture mode to more ductile for all composites.