Microstructure dependent dislocation density evolution in micro-macro rolled Al2O3/Al laminated composite

Abstract

Flake powder metallurgy (FPM) combined with micro/macro-rolling (MMR) was employed to fabricate Al2O3/Al laminated composites with high dislocations storage capability. The effect of deformation mode on the laminated ultrafine grain structure and on the dislocations density was analyzed. Additionally, a model based on microstructure and processing parameters is proposed to describe the effect of size, aspect ratio and crystallographic textures of the matrix grains on dislocation density. It was shown that the dislocation density depends on Al2O3 dispersion degree and Al2O3-Al interfacial bonding level. They are further driven by mechanical micro-rolling process, as well as grain refinement, crystallography texture, and high aspect ratio resulted from macro-rolling process. It was demonstrated that the MMR process provides the laminated ultra-fined grains (UFGs) with higher dislocation storage capability with respect to equiaxed grains. The described process provides a good coordination between the Al2O3 dispersion, Al2O3-Al interfacial bonding as well as crystallographic textures, size and shape of the matrix grains.