Effect of Mg₂Si Concentration on the Dry Sliding Wear Behavior of Al–Mg₂Si Composite

The microstructural morphology and wear behavior of as-cast Al–X wt% Mg₂Si (X = 0.0, 5.0, 10.0, 15.0, and 20.0) composites were investigated through optical microscopy (OM), energy dispersive X-ray (EDX) spectrometry, scanning electron microscopy (SEM), and field emission scanning electron microscopy (FESEM). The dry sliding wear behavior was studied against an EN 31 hardened steel disk at four different applied loads (19.6 N, 29.4 N, 39.2 N, and 49 N) with a sliding speed of 62.8 m/min for 1 h. The optical microscopy analysis exhibits that the primary Mg₂Si particles average equivalent diameter and volume fraction are increased with an increase in Mg₂Si (Mg and Si) concentration in the Al–Mg₂Si composite. Therefore, the bulk hardness of the composites is increased, whereas the primary Mg₂Si hardness decreased because the coarser primary Mg₂Si particles have less compactness. The wear resistance of the commercially pure aluminum significantly improved due to Mg₂Si reinforcement, and the wear resistance is increased with the increase in Mg₂Si concentration up to 15.0 wt% and then decreased at 20.0 wt%. The tested composites worn surfaces and debris exhibit adhesion, delamination, microcutting-abrasion, abrasive- and oxidation-type wear mechanism.