Al6061 alloy is effectively used in the construction, aerospace, and automotive industries due to its high strength-to-weight ratio, but it exhibits inferior wear performance. A possible method for improving the tribological characteristics of Al6061 alloy through microstructural alteration is the friction stir process (FSP). The current article correlates the outcomes of the number of passes of the tool with mechanical and tribological properties. Furthermore, carbon particles such as graphene have been reinforced in Al6061 metal matrix so as to understand their impact on mechanical and wear properties. Over two passes of friction stir process, graphene-reinforced metal matrix composite (MMC) reveals improved performance over the unprocessed sample, leading to its effectiveness towards tribology. Macrograph observation revealed the flow of plasticized material from the retreating side to the advancing side. Retention of graphene particles inside the stir zone was confirmed by the appearance of the G-band and 2D-band through Raman spectroscopy. Microhardness observation revealed a peak hardness of 138.93 ± 1.29 HV for the graphene-reinforced metal matrix as compared with the untreated sample 61.57 ± 0.03 HV.
A significant reduction in wear volume (from O ∼ 0.23 ± 0.006 × 10−3 mm3 to T/G-2 ∼ 0.058 ± 0.003 × 10−3 mm3) and coefficient of friction (from O ∼ 0.71 ± 0.014 to T/G-2 ∼ 0.29 ± 0.005) was observed in the case of graphene-reinforced MMC for two passes of the tool, attributed to its self-lubricating behavior. Furthermore, a decrement in crystallite size was observed for graphene-reinforced MMC (T/G-2 ∼ 27 ± 3 nm) as compared with untreated material (O ∼ 48 ± 3 nm). Additionally, oxide layer formation on the counter surface contributed to improved tribological performance, highlighting graphene’s effectiveness in enhancing wear resistance and frictional characteristics.
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