Microstructure and Wear Resistance of (Mg2Si + SiCp)/Al Composites

The microstructure and wear behaviors of Mg2Si/Al composites with 0 wt.%, 5 wt.%, and 10 wt.% SiC particles were studied using XRD, OM observation, SEM observation, EDS analysis, an extraction experiment, a hardness test, and the dry sliding wear test. It is shown by the results that after the addition of 10 wt.% SiC particles, the population of primary Mg2Si particles increased, while the mean size of these particles reduced from 40 ± 10 μm (in the SiC-free composite) to 25 ± 8 μm. Both the matrix and the eutectic structure were refined. The tetrakaidecahedral morphologies of Mg2Si crystals were confirmed by the results of extraction tests. The wear test results with GCr15 steel as the friction pair show that the Mg2Si/Al composite with 10 wt.% SiC particles displayed more favorable wear resistance than the specimens with 0 wt.% and 5 wt.% SiC particle additions under both constant load and constant sliding velocity conditions. Under applied loads of 10 N, 20 N, and 30 N at a fixed sliding speed of 300 r/min, the wear rate of the Mg2Si-Al composites reinforced with 10 wt.% SiC particles was 36.01%, 48.29%, and 23.32% lower than that of the SiC-free composites, respectively. When the sliding speed was set to 300 r/min, 550 r/min, 750 r/min, and 1000 r/min under a constant applied load of 20 N, the wear rate of the 10 wt.% SiC-reinforced Mg2Si-Al composites was reduced by 40.37%, 40.87%, 26.20%, and 25.78%, respectively, compared with the SiC-free counterparts. The wear failure mechanisms of (Mg2Si + SiCP)/Al composites were mainly adhesive wear and abrasive wear, but the proportion of oxidation wear increased after the addition of the SiC particles.