Effect of graphene nanoparticles on the physical and mechanical properties of the Al2024-graphene nanocomposites fabricated by powder metallurgy

Abstract

Recently, a growing interest has been dedicated towards improving the properties of Al alloys for use in various industrial applications. In this sense, mechanical alloying technique followed by sintering process at 460 and 560 °C in argon atmosphere was used to prepare Al2024 alloy matrix nanocomposites-reinforced by different graphene contents up to 2 wt%. Both XRD technique and TEM were employed to characterize the prepared nanocomposites powders. Microstructure analysis was performed on the sintered composites using SEM. Moreover, the relative density, corrosion rate, thermal expansion and electrical properties of the sintered nanocomposites were measured. Furthermore, their mechanical properties were measured with ultrasonic non-destructive technique. SEM and TEM micrographs revealed a uniform distribution of graphene in the Al alloy matrix. The relative density, coefficient of thermal expansion (CTE) and electrical conductivity of the specimens sintered at 460 °C decreased until reached 90.9%, 13.6 × 10−6/°C and 8.41 × 105 S/m, respectively as the graphene content increased to 2 wt%, while they increased to 93.8%, 1.5 × 10−6/°C and 4.20 × 106 S/m as the sintering temperature increased to 560 °C. On the other hand, the mechanical properties of the nanocomposites such as microhardness, elastic modulus and yield strength were enhanced to 155, 134 and 97%, respectively after adding 2 wt% graphene and sintering at 560 °C. Additionally, the corrosion rate decreased from 5.74 to 2.73 and 5.34 to 2.59 for the sample having 2 wt% graphene and sintered at 460 and 560 °C with increased the exposure from 24 to 144 h, respectively.