Microstructure Dependent Dislocation Density Evolution in Micro-macro Rolled CNT/Al Composite

Abstract

Flake powder metallurgy combined with micro/macro rolling was employed to produce CNT/Al composites. The effect of deformation mode on the lamellar ultrafine grain structure and on the dislocation density was analyzed. Additionally, a model based on microstructure and processing parameters is proposed to analyze the effect of size, aspect ratio and crystallography texture of the matrix grains on dislocation density. It was shown that the dislocation density depends on CNTs dispersion degree and CNT-aluminum interfacial bonding level as a consequence of micro rolling process, as well as on the grain refinement, crystallography texture, and high aspect ratio resulted from macro-rolling process. It was demonstrated that the micro/macro rolling process provides the lamellar ultrafine grains with higher dislocation storage capability with respect to equiaxed grains. The described process indicated that it could provide good combination between the CNTs dispersion, CNT-aluminum interfacial bonding as well as crystallography texture, size and shape of the matrix grains.