Effect of Extrusion Parameters on Microstructure and Mechanical Properties of SiC Particle Reinforced Mg-3.6Zn-0.6Y-0.2Ca Matrix Composites

The microstructures and mechanical properties of a newly developed Mg-3.6Zn-0.6Y-0.2Ca matrix composite containing SiC particle before and after extrusion were investigated. Results show that the grain sizes of the as-extruded composites decrease as compared to the as-homogenized composite before extrusion. With increasing the extrusion speed or extrusion temperature, the size of recrystallized grains increases while the volume fraction slightly increases. The size of dynamic precipitated phases increases and the volume fraction decreases with increasing the extrusion speed. With an increase in extrusion speed from 0.01 mm/s to 0.1 mm/s at 230 degrees C or extrusion temperature from 190 degrees C to 230 degrees C at 0.1 mm/s, the yield strength and ultimate tensile strength decrease while the elongation increases. The yield strength, ultimate tensile strength and elongation of composites extruded under optimized extrusion parameters (190 degrees C, 0.1 mm/s) are 312.0 MPa, 347.3 MPa and 6.6%, respectively. The contribution of grain refinement strengthening to the strength increment is higher relative to the thermal expansion effect and precipitate strengthening.