Comparative study of powder characteristics and mechanical properties of Al2024 nanocomposites reinforced with carbon-based additives

Abstract

This study investigates the effects of nano-graphite (n-Gr), graphene nanoplatelets (GNPs), and carbon nanotubes (CNTs) as reinforcements on the powder characteristics, and physical and mechanical properties of Al2024-based nanocomposites fabricated via mechanical milling. Reinforcement content was varied from 0.5 wt% to 2 wt%, and the impact of the reinforcement type on particle size, morphology, hardness, and tensile strength was systematically evaluated. Results reveal that n-Gr reinforced composites exhibited flaky morphologies, higher particle sizes, and reduced hardness and tensile strength, attributed to limited embedding and agglomeration effects. In contrast, GNPs and CNTs demonstrated superior reinforcement capabilities, leading to finer powder sizes, enhanced hardness, and improved tensile strength. The largest powder size and the lowest particle hardness were obtained in the K₂ sample, measuring 52 µm and 130 HV, respectively, while the smallest powder size and the highest particle hardness were observed in the G₂ sample, measuring 29.4 µm and 179 HV, respectively. Among the reinforcements, GNPs showed the highest embedding efficiency and mechanical performance, achieving peak hardness and tensile strength at 1.5 wt% reinforcement. The hardness and tensile strength values of Al sample were 105 HB and 220 MPa, respectively, while the G_1.5 sample achieved values of 151 HB and 284 MPa, corresponding to approximately 50 % and 29 % increases. For CNTs reinforcement, the C₁ sample exhibited 16 % and 20 % increases, whereas n-Gr reinforcements consistently resulted in reductions.