Enhanced dry sliding friction and wear behaviors of Mg-Mg2Si composites

Dry sliding tribological behaviors of the as-cast (AC) and multi-pass friction stir processed (FSPed) Mg-2Si alloys (Mg-Mg2Si composites) were evaluated using pin on disk method under different loads of 15, 30 and 45 N. In general, FSP implementation and pass number increase reduced the average grain size, fragmented the Mg2Si particles and rearranged them more uniformly in the structure. Hence, the intensive microstructural modification (particularly after 2nd pass) improved the hardness and ductility of the substrate and led to enhanced O-rich tribolayer steadiness and reduced the wear rate and friction coefficient (FC). In the optimum condition (4-pass FSPed sample), the mass loss and FC reduced by about 71% and 46% compared to AC composite. Wear mech-anisms of AC and FSPed composites were also studied.