Effect of thickness reduction of strong staggered spinning on the interface microstructure, texture evolution and mechanical properties of Al/Cu composite tubes

In this work, a novel type of Al/Cu composite tubes were successfully produced by strong staggered spinning with good surface quality, and the effect of thickness reductions on the microstructure and bonding mechanism of interface and the texture evolution of component layers. The results show that the original intermetallics layer in base material (BM) cracks and twists during spinning, and the contact area between fresh Al and Cu increases, resulting in a new diffusion layer containing AlCu, Al₂Cu₃ and Al₄Cu₉ phases from Al to Cu matrix, which presents a hardness between Cu and Al and facilitates stress transfer and deformation coordination. Cu atoms show a higher diffusion rate partly because grains, fragments or atomic clusters of Cu are pushed or sheared into Al and partly because abundant GBs and dislocations in Al provide excellent channels for the rapid diffusion of Cu atoms. With the increase of thickness reduction, Cu grains are elongated in S25 % and kinking of deformation zones are formed in S70 %, and the corresponding grain size decreases from 1.45μm to 0.98μm with a {111} < 112 > shear texture. Besides, Cu grains with orientation of < 001 > //AD are more prone to deformation and gradually change their orientation to < 111 > //AD, causing a growth of texture intensity in S70 %. The extent of grain refinement of Al near Cu is larger than that of Al away from the interface owing to the shear effect of interface, and the latter ones change from elongated grains to equiaxial grains as the increase of thickness reduction because of the extensive DRX, resulting Cube {100} < 001 > texture with the highest intensity of 14.1 among the three tubes. Interface delamination is not observed during tensile tests, although the interface microstructure varies. The well-bonded interface, refinement strengthening and work hardening enhance the UTS of S70 % to 172.89 MPa, increasing by 56.7 % compared with that of BM (110.34 MPa).