Abstract
Abstract The development of carbon nanotubes reinforced metal matrix composites merits relevant attention due to its capacity of improve the hardness and strength of the metal. However, the production of this kind of composite presents many challenges, such as the dispersion and adhesion of carbon nanotubes in the metallic matrix, wich may affect the composite consolidation. The present study aimed the development of composites using an age hardening aluminum alloy reinforced with 0.5 wt.% of multiwalled carbon nanotubes (MWCNT) as well as a hybrid composite based on the mixture of pure aluminum powder and the former composite. AA7050 alloy and pure aluminum matrix composites were processed by ultrasonic mixing, hot pressing and hot extrusion. Subsequently, the materials were submitted to aging heat treatments. The samples were analysed by Scanning Electron Microscopy, X-Ray Diffraction, Atomic Force Spectroscopy, Raman spectroscopy, and Vickers microhardness. It was verified the feasibility in manufacturing the composites by the powder metallurgy route proposed in this work. The AA7050 composite reinforced with 0.5 wt.% MWCNT presented higher hardness than other similar composites in the literature with higher carbon nanotubes content. The aged composite hardness increased 72% in comparison with the present one in the as extruded condition.
Highlights
The development of lightweight metal composites, such as carbon nanotubes reinforced aluminum matrix (CNT/ Al), allows changes in properties of the pure metal or alloy without adding weight
Carbon nanotubes tend to stick together into clusters due to the secondary van der Waals forces[27,28], even after chemical and mechanical processing. These multiwalled carbon nanotubes (MWCNT) agglomerates significantly impair the total consolidation of the material, being considered one of the biggest challenges in the fabrication of metal matrix composites with CNT
Two composites were developed by a powder metallurgy route
Summary
The development of lightweight metal composites, such as carbon nanotubes reinforced aluminum matrix (CNT/ Al), allows changes in properties of the pure metal or alloy without adding weight. Several investigations show an improvement in the mechanical properties of pure Al by incorporating carbon nanotubes (CNT)[1,2,3,4]. Different reports indicate that carbon nanotubes increase the strength[6,7,8], and affect the precipitation kinetics[9,10,11] in age hardenable alloys. The improvement of other properties such as electrical and thermal conductivity[12,13,14,15]
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