Microstructure evolution and mechanical properties of Mg matrix composites reinforced with Al and nano SiC particles using spark plasma sintering followed by hot extrusion

In this study, Mg powders, Al and nano SiC particles were uniformly mixed by mechanical stirring assisted with ultrasonic vibration method. Then reinforced Mg-1Al-xSiC (x = 0.3, 0.6, 1.2, 2.4 wt %) composites were successfully fabricated by spark plasma sintering (SPS) followed by hot extrusion. Experimental results revealed that there was a nearly uniform distribution and good dispersion of nano SiC particles within the Mg matrix, although some of localized agglomerates were found in the matrix. Mechanical properties tests indicated that the addition of nano SiC particles along with 1.0 wt % Al particles to pure Mg resulted in a significant enhancement in tensile and compressive properties of the Mg-1Al-xSiC composites. Compared to monolithic Mg, Mg-1Al-1.2SiC composite exhibited higher 0.2% tensile yield strength (176 MPa vs. 98 MPa, increased by ∼80%), ultimate tensile strength (246 MPa vs. 188 MPa, increased by ∼31%), 0.2% compressive yield strength (140 MPa vs. 81 MPa, increased by ∼73%) and ultimate compressive strength (338 MPa vs. 255 MPa, increased by ∼33%) without much reduction on failure strain.