Investigation and comparison of the effect of graphene nanoplates and carbon nanotubes on the improvement of mechanical properties in the stir casting process of aluminum matrix nanocomposites

Nanocomposites including engineering materials that absorbed a great deal of scientist’s attention due to their excellent properties such as high strength and corrosion resistance. Optimization of development process and careful application of reinforcing nanoparticles are some approaches to improve mechanical properties. Thus, stir casting is considered as a dispersion method of reinforcement in melt. According to the properties of carbon-based particles, graphene nanoplates and carbon nanotubes were used as reinforcing particles in three different percentages including 0.01, 0.05, and 0.1 wt% in the initial alloy A356. Optimum conditions were determined by graphite stirrer with rotational speed of 500 rpm, in a continuous mode at 740 °C for 1 min. Elemental and phase analysis confirmed formation and distribution of reinforcing nanoparticles in a composite matrix. Tensile and compression strengths raised as a result of increment in reinforcement amounts. So that maximum increases of 28% and 55% were respectively reported for tensile and compression strengths using 0.1 wt% of graphene, compared with the sample containing minimum amount of reinforcement. Also 0.1 wt% carbon nanotube led to increase in nanocomposite hardness up to 88.4, indicating an improvement of 33%, compared with the reinforcement-free alloy. Increase of impact energy by 51% in the presence of 0.1 wt% carbon nanotubes has been the maximum enhancement in impact energy in the Charpy impact test, compared with the minimum amount of application in the same reinforcement.