Strain Rate Sensitivity and Deformation Mechanism of Carbon Nanotubes Reinforced Aluminum Composites

The deformation mechanism of carbon nanotubes (CNTs) reinforced Al (CNT/Al) composites at room temperature is yet to be discovered. In this study, CNT/Al composites and ultrafine-grained (UFG) Al prepared by flake powder metallurgy were subjected to strain rate jump tests to study the effect of CNTs on the deformation mechanism of the UFG Al. The results showed that the addition of CNTs greatly influenced the deformation behavior and microstructure, and with CNTs increasing from 0 to 2volpct, the strain rate sensitivity increased from 0.015 to 0.024, while the apparent activation volume decreased from 71.7 b(3) to 39.3 b(3). This phenomenon originated from both the CNTs constrained grain refinement and the increasing dislocation density caused by CNTs, nanocrystalline grains, and intragranular Al4C3. Thermal activation analysis indicated that the rate-controlling mechanisms of both the UFG Al and CNT/Al composites were the forest dislocation cutting. This work may provide insight into stabilizing uniform tensile deformation by increasing strain rate hardening in metal matrix composites.