Superplastic behavior of carbon nanotube reinforced aluminum composites fabricated by flake powder metallurgy

Superplastic deformation of a carbon nanotube reinforced aluminum alloy matrix composite (CNT/6061 Al) fabricated through Flake powder metallurgy (Flake PM) was investigated using uniaxial tensile tests under different temperatures and different strain rates. The result showed that the maximum elongation at 853 K was 106% at strain rate of 4.17E−1 s−1, while the maximum elongation at 673 K was 89% obtained at 4.17E−1 s−1. Threshold stress was evident at lower temperature but insignificant at higher temperature. Strain rate sensitivity and apparent activation energy was determined to be 0.33 and 87.3 kJ/mol, respectively, indicating the grain boundary diffusion controlled mechanism was dominant for this material. With the increase of temperature, partial liquid phase appeared and the reaction of CNT was intensified, which indicated the superplastic deformation of CNT/6061 Al should be conducted at lower temperature (673 K).