Characterization of Al/MWCNTs composites prepared by powder metallurgy routes

Abstract

Aluminum (Al) matrix composite reinforced with 0.5% in weight of multi-walled carbon nanotubes (MWCNTs) are synthetized by powder metallurgy. Spark plasma sintering (SPS) or hot pressing (HP) are used to obtain fully dense materials. Moreover, particular attention is given to the powder preparation in order to uniformly disperse the nanotubes within the metal matrix. To that end, successive mechanical and chemical treatments are applied to MWCNTs. These treatments are described here. The dispersion improvement is assessed by composite micro-hardness measurements which reveal an increase of about 25% compared to pure Al. Furthermore the microstructure study highlights the formation of a complex phase at grain boundaries. The CNT dispersion process optimization combined to the mechanical properties and microstructure investigations should allow a better understanding of the reinforcement mechanisms in this composite.