Grain boundary engineering process for nano reinforced aluminum matrix composites

Abstract

It is challenging to obtain a balance of strength and ductility for alloys and their composites. They are expected to exhibit good comprehensive properties by adjusting the grain boundary character and/or introducing twin structures. However, for coarse grained aluminum with high stacking fault energies, twin structures are rarely found. In this study, a grain boundary engineering process was carried out on coarse grained aluminum containing nano-reinforcements via an alternated compression deformation, followed by an annealing treatment. The effects of the thermo-mechanical process and alloy elements on the microstructures of the composites were analyzed. The mechanical properties and inter-granular corrosion properties of the composites were evaluated. Twin structures could be generated in these alloys. After thermo-mechanical process, the composites exhibited good plasticity as well as higher strength. A Σ3 twin boundary hindered inter-granular corrosion crack propagation. The formation mechanism of the twin structures and the strengthening mechanism are discussed.