Effect of hot extrusion on wear properties of Al–15 wt.% Mg2Si in situ metal matrix composites

•Increasing the extrusion ratio, enhanced the hardness of the composites.•Extrusion process led to a significant improvement in wear resistance.•Wear rate of the composites increased with changing the applied load from 10 to 20 N.•The dominant wear mechanisms of the extruded composites found to be abrasive.

Al–15 wt.% Mg2Si composites were prepared by in situ casting and characterized in wear tests. Previous to the extrusion of specimens at 470 °C – varying extrusion ratio (7.4, 14.1 and 25), the as-cast composites were homogenized at 500 °C for 5 h, followed by slow furnace cooling. The microstructure, hardness and sliding wear behavior were characterized for both, the as-cast and hot extruded composites. Results show that increasing the extrusion ratio causes a significant improvement in hardness and wear resistance. This is ascribed to the observed decrease in average size and better distribution of Mg2Si particles, in tandem with a remarkable decrease in porosity percentages, which goes from 5.63 in the as-cast condition, to 0.47 at the extrusion ratio of 25. It was found that abrasion is the dominant wear mechanism in all extruded composites, whilst a combination of adhesion and delamination appears to be the governing mechanism for as-cast composites.