Effect of graphite exfoliation through multipass friction stir processing on microstructure and mechanical properties of aluminium 7075-silicon carbide-graphite compositesEinfluss der Graphitablosung durch Mehrfach-Ruhrreibschweissen auf das Gefuge und die mechanischen Eigenschaften von Aluminium 7075-Siliciumkarbid-Graphit-Verbundwerkstoffen

In this study, friction stir processing techniques has been utilized to fabricate graphite-reinforced aluminium matrix composite. Silicon carbide will be mixed together with graphite flakes as reinforcement with the composition of hybrid ratio 60 : 40. The manipulated variable of this project is the number of passes used during friction stir processing (1, 2 and 3 passes). Three different number of passes are used to investigate its effect onto the reinforcement dispersion inside the aluminium metal matrix composites. Microstructural analysis has shown that with increasing number of passes, the distribution of reinforcement particles becomes more uniform and homogeneous. Nanoreinforcement particle dispersions are observed and analysed. Result shows that the size of agglomerations across the composite surface decreases as the number of passes increases. Further observation and analysis of on the particles has confirmed that graphite flakes have been successfully shear exfoliated into layers to cover more surface area. The overall mechanical properties have also observed significant increase with increasing number of passes. Sample with highest number of pass (3 pass run) managed to achieve maximum tensile strength and elongation percentage of 304.04 MPa and 2.54 %, respectively, which is the highest value among all the samples tested.