Production and characterization of an advanced AA6061-Graphene-TiB2 hybrid surface nanocomposite by multi-pass friction stir processing

In this study; by the implementation of multi-pass friction stir processing (FSP) an advanced AA6061-Graphene-TiB2 hybrid surface nanocomposite is produced in contrast to the AA6061-Graphene and AA6061-TiB2 single composites. Effects of micro-sized TiB2 (10-30 wt%) and nano-sized graphene (0.5-2 wt%) particles on the microstructure and mechanical property of aluminum alloy are investigated. Moderate chemical composition as similar to 20 wt% TiB2 and 1 wt% graphene for the hybrid nanocomposite system yielded the best combinations of mechanical property overcome the wear-strength trade-off. Such optimum incorporation of hybrid inclusions mixture led a hardness increasing up to about two times higher, a yield strength improvement up to similar to 225 MPa (similar to 300% increasing ratio), and an elongation loss down to similar to 9%. A considerable reduction in the coefficient of friction similar to 23% is revealed with the dominant contribution of sliding wear fractographic features on the worn-out fracture surface due to the presence of graphene in the nanocomposite structure acting as the lubricant agent.