Mechanical, metallurgical and tribological properties of friction stir processed aluminium alloy 6061 hybrid surface composites

Abstract

Abstract Friction stir processing (FSP) was applied in the fabrication of aluminium hybrid surface composites by embedding reinforcement particles namely, aluminium oxide (Al2O3), boron nitride (BN) and Graphite (Gr) with Boron carbide (B4C) in an equal volume basis. Three FSPed plates were fabricated at constant tool rotational speed of 1000 rpm, welding speed of 30 mm min−1 and axial force of 6 kN. The microstructure showed the homogeneous dispersion of reinforcement particles and good interfacial bonding between the reinforcement particles and the base material was observed in the processed zone. In terms of strength and hardness, surface composites with B4C and Al2O3 combinations yielded better mechanical properties over other the combinations. The results of wear studies reveal that the FSPed surfaces exhibited better resistance to wear when compared to the base material in a dry sliding condition. The dominance of abrasive wear was observed in all cases of the surface composites inspite of few micro cracks and delamination found on the worn surface. XRD analysis suggests that no secondary phases or intermetallic was formed anywhere in the processed zone.