Abstract:The AA6061-10wt.%B₄C mono composite, AA6061-10wt.%B₄C-Gr (Gr: graphite) hybrid composites containing 2.5, 5, and 7.5 wt.% Gr particles, and AA6061-10wt.%B₄C-MoS₂ hybrid composites containing 2.5, 5, and 7.5 wt.% MoS₂ particles were fabricated through stir casting. The dry sliding tribological behaviors of the mono composite and hybrid composites were studied as a function of temperature on high temperature pin-on-disc tribotester against EN 31 counterface. The wear rate and friction coefficient of the Gr-reinforced and MoS₂-reinforced hybrid composites decreased in the temperature range of 30-100 °C due to the combined lubrication offered by the wear protective layer and its solid lubricant phase. Scanning electron microscopy (SEM) observation of the worn pin surface revealed severe adhesion, delamination, and abrasion wear mechanisms at temperatures of 150, 200, and 250 °C, respectively. At 150 °C, transmission electron microscopy (TEM) observation of the hybrid composites revealed the formation of deformation bands due to severe plastic deformation and fine crystalline structure due to dynamic recrystallization.

Key words: aluminum hybrid composites; high temperature tribological behavior; solid lubrication; deformation band; dynamic recrystallization