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Abstract
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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
~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 ~225 MPa
(~300% increasing ratio), and an elongation loss down to ~9%. A considerable reduction in the coefficient of
friction ~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.
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