EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Abstract: Aluminium alloys and composites are the preferred structural materials for aerospace applications, considering their superior multifunctional properties (high strength-to-weight ratio and fatigue resistance and increased resistance to stress corrosion cracking), which are highly desirable for aircraft and spacecraft structures. Maximum use shall be made of aluminium metal matrix composites (MMC), especially for structural parts, to decrease the mass without compromising reliability and for minimizing susceptibility to general corrosion, pitting, intergranular and stress corrosion cracking. Considering their outstanding performance, carbon nanotubes (CNTs) showed great potential as a reinforcing material for Al MMC. In this study, some new hybrid carbon nanotube reinforced aluminium (H-CNT/Al) nanocomposites were developed, having a 2024 aluminium metal matrix and a hybrid double discontinuously reinforcing network, consisting of 10% SiC particulates and multi-walled carbon nanotubes (MWCNTs) in varying proportions (1% – 5%). The resulting nanocomposites were further thermomechanically (TM) processed by different routes, to promote not only the densification and microstructural refinement of the samples, but also the uniform distribution and even the alignment of CNTs with a certain direction. From each processing stage, samples were advanced characterized from chemical, microstructural (phase structure, phase parameters, grain size, reinforcements characteristics and distribution), and mechanical (yield strength, ultimate strength, elastic modulus, micro-hardness) points of view. The H-CNT/Al nanocomposites fatigue resistance and the susceptibility and resistance to stress-corrosion cracking (SCC) were also assessed, to investigate the influence of synthesis and TM processing conditions on the microstructure and mechanical properties of newly developed composites and also for fine-tuning the synthesis and TM processing parameters.

Keywords: aluminium metal matrix composites; carbon nanotubes; thermomechanical processing; microstructural characterization; mechanical properties; aerospace applications.

Acknowledgments: This work was supported by a grant of the Romanian Ministry of Education and Research, CCCDI - UEFISCDI, project number PN-III-P2-2.1-PED-2019-5134, contract 492PED/2020, within PNCDI III.