Effect of ball milling processing on mechanical properties of extruded aluminum-graphene-composites with commercial and self-synthesized graphene sources

Abstract. In this study the effect of ball milling processing on the mechanical properties of extruded aluminum-graphene-composites was investigated. A commercial and a self-synthesized graphene source was applied respectively. It was found that rods of extruded high speed ball milled (HSBM) materials showed bad surface quality with massive cracks. The extrusion loads in indirect extrusion were 100% higher for HSBM material compared to material that was ball milled at lower rotation speed (LSBM). Investigations of mechanical properties revealed that for HSBM material TYS was increased 92% and UTS 118% compared to LSBM. Microhardness was also found to increase by up to 210% for HSBM material containing 1% graphene. However, since pure aluminum processed under same conditions also featured a drastic increase in hardness of 167%, it can be concluded that work hardening of the pure aluminum matrix seems to be the main strengthening mechanism. Furthermore, graphene agglomerates could be found locally in all extruded samples.