Effect of Milling Speed and Time on Graphene-Reinforced AA2024 Powder

Aluminium is the third most abundant material in the Earth’s crust and, along with its alloys, is essential in many engineering sectors, including aerospace, automotive, defence, marine, construction, and medicine, owing to its high damage tolerance, fatigue resistance, conductivity, corrosion resistance, and low density. Despite this, some mechanical properties of Aluminium do not yet satisfy increasing industrial demands. Reinforcing aluminium alloys with other elements is considered as a means of providing additional strength. This study aims to investigate the effect of milling speed and time on graphene-reinforced aluminium alloy powder, intended for use in selective laser melting (SLM), prepared using high-energy ball milling (HEBM). The experimental study indicates that using a slow milling speed (100 rpm) for up to 2 h does not affect the shape of the powder substantially, and the graphene nanoparticles (GNPs) do not adhere to the powder surface in a metal matrix composite (MMC). However, a faster milling speed (250 rpm) flattens and crumbles the powder, and adheres the graphene sheets to the alloying powder, due to the higher impact energy produced by centrifugal and Coriolis forces.