Evaluation of thermal stability of ultrafine grained aluminium matrix composites reinforced with carbon nanotubes

• Published in: Composites science and technology 2011-11, Vol.71 (16), p.1881-1885
• Main Authors: Lipecka, Joanna, Andrzejczuk, Mariusz, Lewandowska, Małgorzata, Janczak-Rusch, Jolanta, Kurzydłowski, Krzysztof J.
• Format: Article
• Language: English
• Subjects: A. Carbon nanotubes; A. Metal matrix composites (MMCs); Aluminum base alloys; Aluminum carbides; Annealing; Applied sciences; B. Thermal stability; Carbides; Carbon nanotubes; Dispersion hardening metals; Exact sciences and technology; Metals. Metallurgy; Nanocomposites; Nanomaterials; Nanostructure; Powder metallurgy. Composite materials; Production techniques; Ultrafine grained aluminium alloys
• ISSN: 0266-3538; 1879-1050
• DOI: 10.1016/j.compscitech.2011.09.001

► Thermal stability of Al/CNTs composite has been examined. ► The addition of carbon nanotubes enhances the thermal stability of ultrafine grained Al. ► After annealing at 450 °C (0.7 T m ) no evident grain growth is observed. ► It results from the presence of highly entangled agglomerates of CNTs at grain boundaries. ► At a temperature of 450 °C, CNTs transform into nanoscale Al 4C 3 particles. The effect of carbon nanotubes on the thermal stability of ultrafine grained aluminium alloy processed by the consolidation of nano-powders obtained by mechanical alloying was evaluated via measurements of grain size and mechanical property changes upon annealing at various temperatures. It was found that the grain size of the samples containing carbon nanotubes is stable up to high temperatures and even after annealing at 450 °C (0.7 T m ) no evident grain growth was observed. The limited grain boundary migration was attributed to the presence of entangled networks of carbon nanotubes located at grain boundaries and to the formation of nanoscale particles of aluminium carbide Al 4C 3. It was also revealed that carbon nanotubes decompose at a relatively low temperature of 450 °C and form fine Al 4C 3 precipitates. This transformation does not significantly affect the mechanical properties due to the nanoscale size of the carbides.