Sic_p/ew61 Organization And Properties Of The Magnesium Matrix Composite Materials Research

SiCp/EW61composites with average particle sizes of0.7μm and6μm and four weight percent of1wt.%,2wt.%,3wt.%,4wt.%were fabricated by semi-solid stir-casting technique, and these composites were then secondly-processed by hot extrusion and friction stir processing (FSP). The microstructures and mechanical properties of the composites were examined by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), hardness and tensile testing. The conclusions are as follows.The SiC particles mainly distributed along the grain boundaries in as-cast composites, and tended to agglomerate as the average particle sizes get smaller or particle weight percent arises. The boundary strength between SiCp and the matrix was weak, which led to the low elastic modulus, yield strength and ultimate tensile strength of the as-cast composites.After hot extrusion, the porosity was eliminated, and the composites had a dense structure along with dispersed particles, which led to an improvement of mechanical properties of as-cast composites. The elastic modulus of as-extruded6μm1wt.%SiCp/EW61composite increased8GPa compared to the matrix alloy. The0.7μm1wt.%SiCp/EW61composite exhibited a equal increase of the elastic modulus as the6μm1wt.%SiCp/EW61composite, while the yield strength and ultimate tensile strength were relatively higher. For the composites with the same particle size, the elastic modulus decreased with the increase of particle weight percent, and the yield strength and ultimate tensile strength increased first and then decreased.The composition and type of the second-phase particles remained the same after FSP, while the distribution changed greatly. These particles broken to tiny ones and became disperse in the Stirred Zone. Particles in Themo-Mechanical Affected Zone were also broken but distributed in lines. Particle size and distribution in Heat Affected Zone remained. The elastic modulus of extrusion-FSP-0.7μm1wt.%SiCp/EW61composite increased8GPa compared to the matrix alloy, while the yield strength and ultimate tensile strength were lower.