Investigation of nanostructured aluminum/copper composite produced by accumulative roll bonding and folding process

In this work, the aluminum/copper multilayered composite was fabricated by new severe plastic deformation method named “accumulative roll bonding and folding” (ARBF) process at room temperature. Evolution of structure of the composite was investigated by transmission electron microscopy (TEM). It was demonstrated that ARBF process generated nanostructured aluminum/copper multilayered composite. Occurrence of the recrystallization (both continuous and discontinuous) in the copper layers led to the formation of nanograins with an average size of ∼50 nm while, the average grain size of aluminum layers was ∼200 nm after twelfth cycle of ARBF process. In both the copper and aluminum layers in grains and subgrains smaller than 100 nm almost no dislocations were observed, while grains larger than 200 nm had high density of dislocations. Also, when the number of ARBF cycle increased, the grains became equiaxed. Also as the number of ARBF cycles increased, the microhardness in both aluminum and copper layers increased. Differences in microstructural evolution during processing and hardness values of aluminum and copper layer were related to their stacking fault energies.