Materials Properties and Microstructure of Graphite/Aluminum Composites Fabricated by Friction Stir Processing

Graphite/aluminum metal matrix composite (MMC) with improved yield strength, tensile strength, elongation, and thermal conductivity was successfully fabricated by friction stir processing (FSP). In fabricating the MMC, graphite reinforcement is applied in the form of paste. The results of X-ray photoelectron spectroscopy (XPS) suggest that graphite reinforcements are successfully dispersed into the aluminum matrix by the effect of both the downward force of the tool and plastic material flow during FSP. The yield strength, tensile strength, and elongation of graphite/aluminum MMC are estimated to increase by more than 118%, 58%, and 87%, respectively, compared with those of the aluminum matrix. The thermal conductivity of graphite/aluminum MMC was also measured to increase by more than 16% in comparison with that of the aluminum matrix. It was revealed that both the homogeneous dispersion of graphite into the aluminum matrix and formation of a fine grain structure by FSP improved the mechanical and physical properties of the graphite/aluminum MMC.